Final Report Summary - NMI3-II (Neutron Scattering and Muon Spectroscopy Integrated Initiative)
Executive Summary:
The Neutron and Muon Integrating Infrastructure Initiative – NMI3 – brought together 18 European partners, of which 8 are neutron sources and two of these are also muon sources. NMI3 was structured in three strands: networking activities (NA), joint research activities (JRA) and trans-national access (TNA).
In such an extensive collaborative activity, communication was a primary need, both within and beyond the project - the NMI3 website (nmi3.eu) provided this important communication channel. In addition the international neutronsources.org and muonsources.org portals have been launched in order to assure project-independent sustainability for the scientific community. Particular emphasis was given to promoting the less well-known muon technique to the wider scientific community.
Training students and young scientists in the area of neutron scattering is vital for sustaining neutron and muon based research in Europe. For these experimental techniques, which are restricted to large-scale facilities and may therefore be largely unknown in home institutions, training is particularly important. Based on state-of-the-art IT and best didactical principles, htttp://www.e-neutrons.org provides a freely accessible e-learning portal for neutron scattering for students from bachelor to PhD level as well as researchers who are not regular neutron users. A dedicated full introductory course has been constructed for master-level physics students.
NMI3 supported the distributed training facility NaMES for neutron scattering and muon spectroscopy in Europe. NaMES served about 1500 students over the four years’ period, but hands-on exercises remain still limited and e-neutrons is a very welcome tool to support the NaMES activities and teach more users.
In order to organize access of scientific users to European, large scale neutron and muon facilities, an integrated access format for scientific users has been developed with harmonized proposal forms and optimized peer review processes and demonstrated in a software prototype.
After the experiment, data has to be analysed. The existing, uncoordinated approach to data analysis results in widely varying standards, different user experiences at each facility and single-points of failure in software provision. An analysis of the existing software landscape and coding practices was the starting point of the data analysis networking activity which proposed a set of recommendations for a common European e-infrastructure.
Work associated with the Muon spectroscopy focussed on developing state of the art data reduction, new source technologies and improved detectors to enhance the potential of the technique. New algorithms, together with a link between analysis and simulation codes, provided the user with improved methods for data analysis. Concept studies centred on improved targets, advanced micro-beams and high intensity sources helped the community plan future facility upgrades. Avalanche Photodiode (APD) based detectors have been developed and evaluated for measuring the high instantaneous rates inherent to the pulsed muon beam at ISIS; this work will point the way for the development of future high density detector arrays at the facility.
Neutron imaging is a direct method for non-destructive visualisation of objects in science and technology. Innovative methods have been developed combining real space with reciprocal space approaches and probe micro and nanostructures in bulk materials. The magnetic moment of the neutron allows two- and three-dimensional visualization of magnetic field and domain distributions.
Advanced methods and techniques for neutron experiments at the future European Spallation Source (ESS) have investigated new instrument designs and sample environments. Prototype development in the field of extreme environments, Neutron Spin Echo with oscillating intensities, choppers and polarisation of the totality of the neutron beam for long-pulse instruments are on-going in the context of the future ESS.
Natural biological membranes are highly complex systems so simpler models are needed for structural characterization on the nanometer scale. Soft materials are also very sensitive to various stimuli and the challenge is to use dynamic external stimuli for hitherto unstudied time-dependent processes. New sample environment equipment for humidity, temperature, electric field and pressure underpins new science.
For many years neutron scattering facilities have depended on 3He for a large fraction of their detector requirements. The current and foreseeable penury in supply of 3He requires new technologies for cost effective, large area detectors. This work seeks to develop 6Li-loaded scintillation detectors and gaseous detectors using solid 10B converters as the most promising candidates.
More details (including images and videos) on these NMI3 activities can be found in the periodic reports and on the website (nmi3.eu).
Project Context and Objectives:
WP2 Dissemination and Outreach
Task 2.1 Internet portal as internal and external communication tool
Our ultimate objective was to have an internet portal as well adapted to the current and future needs of the scientific community as possible, with relevant information to the project members and outside world. The NMI3 e-newsletter keeps subscribers informed while attracting visitors to the website.
Task 2.2 Scientific and public outreach
It is essential to widely publicise the successful outcome of activities supported by the project. We thus aimed to create and disseminate material and activities to promote the scientific achievements obtained thanks to NMI3 support.
Task 2.3 Developing the Muon user community
Outreach activities to bring the unique capabilities of muon spectroscopy to the attention of the wider scientific community with the aim of attracting new users to the technique. Developing webpages and publicity material with a focus on high field muon measurements and planning workshops to promote the muon technique.
WP3 E-learning
Educating students and young scientists in the area of neutron scattering is a key for sustaining neutron research in Europe and attracting new users to the large scale facilities. As the curriculum of master courses in physics, chemistry or other related natural sciences does generally not include neutron scattering in any depth, it is essential to dispense such training via additional dedicated actions. The task of this networking initiative is to profit from modern web-based pedagogical tools and to setup an e-learning portal to promote neutron science in Europe.
Several specialized neutron courses organized by research centres and universities exist and provide a comprehensive introduction to neutron techniques often accompanied by hands on training at neutron sources. Access to these training courses is supported by NMI3 in the present project in the work package dedicated to The European Neutron and Muon School (WP4). The continuing success of this training is one of the components that maintain Europe as the leading region for neutron research around the world.
However, the number of participants is strongly limited especially for the practical courses. An open access e-learning platform will diminish this restriction. In addition e-learning is able to provide teaching in neutron research without the constraints imposed by the venue and dates of a neutron school. This is important especially for master- and PhD students starting their research and depending right from the beginning on neutrons for their investigations. Furthermore web-based courses will help to prepare students better for the neutron schools.
They will equally provide in-depth learning units to be used by lectures of graduate schools in e.g. condensed matter science. Finally they will assist undergraduate students attending lectures on neutron scattering or neutron research related courses.
In the present project period (P3) we have mainly focused on
• Preparing a comprehensive entry webpage for presentation and overview of the e-learning project
• Finalising interoperability between the stand-alone software tools which we have developed for the e-learning platform
• Finalising curriculum, course material, learning goals and paths for the modules of the online courses in the platform.
• Finalising interactive learning material utilising the software tools in the platform.
• Providing a forum for sharing experiences with and requests for the e-learning platform and courses within
• Providing a library for sharing learning material from face-to-face neutron schools and other neutron teaching/learning material
• providing best-practice for teachers in terms of user-manuals for development of online courses on the e-learning platform
WP4 NaMES
The project objectives for the period February 2015 – January 2016 were:
i) To undertake the scheduled neutron and muon schools
ii) To build further synergies with WP3 (E-learning)
WP5 Integrated User Access
Easy and open access to large scale neutron and muon facilities by national and international external scientific users is a general mission of all such public-funded scientific institutions in Europe. Peer-reviewed proposal systems are established in most facilities to organize the access of the scientific user in a structured and transparent and scientifically efficient way. Regular calls for proposals for beam time at each individual facility serve the scientific request. Unfortunately the fragmentary structure of the individual user access at the various facilities has been identified as a possible obstacle for the growing user community in Europe. In order to ask for beam time, the users have to redo similar registration procedures at each facility, to fill in similar proposal forms and to provide very similar information on legal and safety requests. Also, the facilities with large numbers of proposals (e.g. more than 600 per year at TUM) need to spend increasing amounts of time and administrative resources in organizing this task. New large facilities such as the European Spallation Source “ESS” with potential high throughput beam lines may deal with even more severe administrative efforts.
Facing these challenges, of increasing user demand and fragmented access structures, an ‘Integrated User Access (IUA)’ Networking Activity has been launched with the NMI3-II Programme in order to develop ideas for a framework to structure and harmonize an integrated access format to European national neutron and muon facilities for the scientific users. The work package consists of the following main objectives:
• Development of a generalized integrated user registration. Technical and legal requirements for a common NMI3 based single electronic user ID to access individual facility digital user office (DUO) systems will be analyzed and the best possible solution will be evaluated and established as a prototype. (Task 5.2)
• Harmonized proposal forms and templates. Forms and templates of proposal submissions at existing DUO applications will be compared and a harmonized proposal template adopted for the individual requirements will be proposed and prepared for implementation. (Task 5.3)
• Web based proposal peer review process. A framework will be developed to allow peer reviewing of submitted proposals within NMI3 web applications for small facilities, which do not operate an individual DUO. (Task 5.4)
• Platforms for cross-source independent beam time access. Platforms to submit proposals for access by the combination of instruments at the NMI3 facilities and platforms for cross-source proposals for the complementary use of instruments, laboratory services or infrastructures using different probes (e.g. neutron, muons, x-rays, facility based AFM or electron microscopy) will be considered and developed. (Task 5.5)
Work on Task 5.2 (D5.1 and D5.2) Task 5.4 (D5.5) and Task 5.5 (D5.7) were already finished and delivered in previous reporting periods. In the final reporting period work on Task 5.3 is was finished and corresponding reports delivered (D5.3 and D5.4). The work on the development of the software prototypes in Task 5.4 and 5.5 (D5.6 and D5.8) could be finished successfully and reports delivered within the time period of the project. Overall the project has successfully worked on all task and delivered planned reports and software prototypes without any severe delay. It is expected that the results of the WP will successfully help to improve and harmonize the user access and service at the neutron and muon facilities in the near future.
WP6 Data Analysis Standards
High resolution detectors and higher data rates, among others, make new demands on software that require professional software solutions. In particular, new instruments constitute a considerable challenge for software provision and failure to address this issue leads to a delay in the scientific impact of new investment.
The importance of data analysis is clear and has become a focal point of efforts to optimise scientific production. The aim of this networking activity is to determine how to develop, deploy and operate a common data analysis software infrastructure to facilitate joint software development in the neutron scattering community.
The Data Analysis Standards networking work-package began with two review tasks: review existing data analysis software and practices of software developers and review existing solutions for a common data analysis infrastructure. Based on the reports from these tasks, the key phase of the project was to develop a small number of prototype software solutions in areas chosen by the partners. The goal was to deploy functionality that exists at some facilities in the common framework thereby making it accessible to and optimised for all partners.
Task 1: Review existing data analysis software and practices of software developers
Task 2: Review existing solutions for a common data analysis infrastructure
Task 3: Develop prototype software in chosen solution for representative applications
Task 4: Evaluate prototype software
WP17 Muons
Task 17.2 Software Development for Muon Data Analysis
Work developing state of the art data reduction methods applicable to new applications of the muon technique. Specifying and coding routines to help user groups get the best from their data, and considering how simulation codes can be exploited during data analysis.
Task 17.3 Concept Studies for Future Muon Sources
Taking a forward look at the next generation muon sources, instrumentation and user requirements. Providing a concept study for a muon micro-beam and investigating requirements for future high intensity sources.
Task 17.4 Detector Technologies for Pulsed Muon Sources
Collaborative work developing Geiger-mode Avalanche Photodiode based detectors for pulsed muon beams. Developing and using a test system to evaluate detector parameters, with a particular focus on characterising device dead time.
WP18 Imaging
The efforts in JRA-Imaging in the current reporting period were focused in finalizing the project and providing of all deliverables. Experiments with external users by using of equipment which was designed and manufactured in the frame of the project were performed. The project partners used the established collaborations for building of equipment, exchange of knowhow, performing of joint experiments and discovering the capabilities of other facilities. Different platforms for simulation and data processing were developed which allow for analysis of experimental data with high precision and reliability.
WP19 Advanced Methods and Techniques
Task 19.1: Sub-mm3 samples for extreme environments
The problem of designing neutron instruments for dealing with small samples in extreme environments was addressed in two ways:
1. Developing focusing optics for a realistic experimental setup such as the IN5 or ThALES instruments at ILL, capable of capturing most of the source brightness and of converting it into a flux increase at the sample.
2. Design the instrument such as to take full advantage of the small solid angle allowed by the extreme sample environment. The conceptual design of instruments optimized for extreme conditions were carried out.
Task 19.3: Spin Echo with Oscillating Intensity for ESS
This task is devoted to developments for the application of Neutron Spin Echo (NSE) and its variant MIEZE techniques at spallation sources, especially at the ESS. The main objectives for this period were:
1. Test the performance of the resonant circuits to modulate the amplitude of the RF field as a function of time in the resonance coils, to keep the amplitude of the resonant magnetic field tuned with the wavelength of the neutrons.
2. Define new measurement strategies and new data analysis concepts to transfer the MIEZE technique from the currently reactor based instruments to a pulsed source as ESS.
Task 19.4: Choppers for the ESS instrumentation
The ESS is planned as intense long pulse neutron source with an effective neutron pulse length of the order of 2ms at a repetition frequency of 10..20Hz. With these parameters it is obvious that at least for all instruments that do not correspond to reactor instruments with velocity selectors (i.e. SANS, NSE, reflectometry) additional pulse shaping is required to achieve a reasonable resolution. This pulse shaping has to be performed by some kind of choppers. One task certainly is to modify existing chopper families (Fermi choppers, disk choppers with and without magnetic bearings) such that they meet the harsher radiation requirements of the ESS environment. The ultimate idea is to compose a Fermi chopper type by an array of slim rotators that are operated synchronously and eventually with adjustable phase shifts. To cover a larger area, a staggered array of these rotors with small diameters is needed. Here we proceed investigating the capabilities, properties and feasibility of such new chopper concepts that may allow for high frequency (KHz), large area and adaptability to focusing strategies. At the same time the kinetic energy shall be limited such that safety issues do not prevent their practical After conceptual test that proved the feasibility of phase control of a slim rotor in air up to 200Hz rotation speed and conceptual design of the rotor by initial FE-calculation now construction drawings and production procedures for a final test with neutrons are in on going preparation that will allow us also to assess the mechanical and neutronic layout of the rotor. For that purpose a construction for a single rotor running in vacuum up to 1KHz is in progress. The results will yield the reports on mechanics and neutronics of the rotor including experimental verification in order to produce substantial design reports.
Task 19.5: Polarising all neutrons in a beam
Polarized neutron beams are widely used for materials sciences investigations covering a broad range of research fields from hard-condensed matter (magnetic materials, superconductors, etc) to soft matter (polymers, proteins, etc.) and biology. Current neutron polarizers act as a spin-filters, and select only one of the two spin-states of the neutron beam (up and down) while discarding the other. Thus polarized neutron beams suffer an intensity loss of at least 50% depending on the performance of e.g. 3He filters or polarizing super-mirror-based devices.
The new design conceived in the frame of this project overcomes the existing limitations and shows that it is possible to flip one polarization (e.g. of the transmitted beam using a broad band radio-frequency flipper) and then recombine the two beams. To satisfy Liouville’s theorem, phase space volume necessarily increases in divergence, but the beam is homogeneous and thus be used for several neutron scattering applications. Numerical simulation were performed to estimate the efficiency of the device.
WP20 Soft Bio Materials
Task 20.1. A platform for model biological membranes
Natural biological membranes are highly complex systems, composed of different lipids, proteins, sterols, etc. As a result of this complexity, native membranes are difficult to study and simpler models need to be devised for structural characterization in the fraction of nanometer scale. Floating bilayer other model membranes systems generally studied suffer from a number of drawbacks and are not always suitable to mimic the complexity of real membranes. A very topical issue in this field is the development of reliable protocols for reconstitution of membrane proteins into model membranes. With these aims, different approaches will be studied to produce reproducible and realistic model membranes for biophysical and biological studies. In addition, there is a need for improved data analysis methods to extract as much information as possible from reflectivity data. A second aspect of the work will be in the development of novel modeling methodology, including molecular scale information from molecular dynamics simulations in the interpretation of NR data. Additionally, the deuteration of lipid compounds is essential for such studies but their chemical synthesis is challenging. We propose to extract natural lipids from the biomass produced from protein deuteration at the D-Lab facility in Grenoble.
Task 20.2. Kinetic/dynamic measurements in periodic external fields
Soft materials are very sensitive to various stimuli (mechanical deformation, electric or magnetic fields, UV or visible irradiation, pH, concentration or temperature variations)... Many of these external fields have been applied mostly statically, and we need now to study responses of the sample to periodic time dependent fields. We wish to extend the accessible fields, and develop kinetics and in situ measurements in neutron scattering.
Stopped Flow (SF) devices are used are used to record real time measurements (including very early stages of 100ms) on a sample after application of an external stimulus (dilution, mixture, pH or T-jump...). A first crucial step to improve both performances and spread kinetics studies with SF equipment could be overcome by improving the filling and emptying of the sample cell and adapting the cell volume and geometry to the amount of “available” samples (design of micro-cells or on the contrary, larger and thicker cell to reduce the number of repetitions). Another important development of these devices concerns a more precise control of temperature in order to follow phase transitions after T-jumps.
Investigation of the wide scale range intermediate states of structures displayed by soft materials is another major challenge for all future technical developments. A combined static LS / SANS setup would complement the standard SANS Q-range to smaller Q range (2 10-4 Å-1 ≤ Q ≤ 3 10-3 Å-1) and would allow accurate monitoring of aggregation phenomena, approach to a phase separation etc. Until now, a combination of SANS and dynamic light scattering (DLS) has been only achieved for a fixed light scattering angle, and static light scattering has never been used before in combination with SANS. We first propose to design such set-up.
External stimuli like UV irradiation can induce chemical reactions, and/or conformational and/or structural changes in soft materials. Application of oscillating electric field is one of them and is scarcely developed since electrolysis often occurs. We aim at developing electric field cell with electrodes outside the sample. Thermalization of the cell has to be provided.
So far, only few high resolution neutron scattering experiments addressed the dynamics of soft matter involving pressure. Some experiments investigated micro emulsions under pressure up to 500 bar, but in the pressure region of several kbar interesting questions can be addressed: proteins, for example, undergo a transition from the folded to the unfolded state not only by an increase of temperature but also at high pressure (about 7 kbar ) as shown by SANS measurements. NSE spectroscopy has a great potential in the study of internal dynamics of unfolded proteins, but its large beam cross section and its requirements of non-magnetic materials are challenging for high pressure devices. We propose to develop a non-magnetic pressure cell accepting a large incoming beam cross section and large exit angles.
Task 20.3. Humidity chamber
In-situ control of the hydration level of soft materials samples plays a crucial role in the investigations of the proton motion in Nafion membranes, the dynamics of phospholipid membranes, the structure and dynamics of clays, as well as in the study of the function/structure relationship of proteins. In the last years, ILL and HZB have been developing humidity chambers for neutron scattering using different techniques to control both relative humidity and temperature. Further developments are needed to obtain first a faster and better controlled response in wider temperature and humidity ranges.
Task 20.4. Cryogen-free cryostat with sample changer
In order to decrease dead times related to temperature and sample changes during neutron scattering experiments in cryostats, it is necessary to design and build a cryostat that features a carousel of samples either placed at room temperature or thermalized at low temperature (for example at 80K by using a cold gas stream), equipped with an automatic sample changer, and capable to extend the available temperature range (down to 3K or lower and up well above room temperature). A more compact design with less cold mass would allow rapid cool-down and sample changes by means of a robot. We propose to design and draw a new cryostat with a sample changer fulfilling these specifications.
WP21 Detectors
Work package 21 is divided into two tasks, each of which seeks to develop a non-3He based detector technology for neutron scattering applications. Task 21.1 examines aspects of scintillation detector technology, while task 21.2 is concerned with the development of gas detectors based on solid 10B converter. Within this period the objectives are to complete the following subtasks:
Task 21.1.5 Detector evaluation and final report
Task 21.2.4 Concept study for large area detectors
Task 21.1.5 builds on the work done in previous subtasks whereby ISIS and Jülich developed scintillation detectors based on ZnS:Ag/6LiF read out with wavelength shifting (WLS) fibres and vacuum photomultiplier tubes (PMTs). This task also continues the work by CNR/Perugia on the development of SiPMs coupled to GS20 glass scintillator. The output of this task is a report, deliverable D21.9 which details the status of the scintillation detector development carried out in this work package.
The output of task 21.4 are two reports, D21.14 and D21.15 which detail the concept studies carried out for large area detectors based on gas detectors with solid 10B convertor. D21.14 is the concept study of a large area detector based on MWPC, while D21.15 is the concept study of a large area detector based on Micromegas.
Project Results:
WP1 – Management
Within the last 48 months the project manager took care of the follow-up of delivery status of the different WP obligations. The project manager keeps track of all issues which may arise and need to be discussed in the Board meetings. She also stays in continuous contact with the project officer.
The project manager composed all necessary documents necessary for the periodic & final reports and the two amendments. This included the financial reports and money transfers to beneficiaries.
She planned and organized the annual General Assemblies with adjacent Board meetings as well as the Advisory Committee sessions and the review of the School reports (NaMES in WP4). The set-up of the respective agendas and discussion points is in the remits of the project manager, who also proposes and invites the external speakers to the resp. event:
In addition to the very efficient and lean project management, the project manager took care of the industry related activities added in WP1 in the negotiation phase. Three major workshops have been held. The first on ‘Industry as a supplier’ held at the ICNS in Edinburgh, 2013. The second strand was ‘industry as a user’ for which an ‘Industry Advisory Board’ has been set-up. This Board includes industrial representatives using both neutrons and synchrotron facilities. The following two workshops have been done jointly with the homologue lightsoures project CALIPSO. More information is available on http://nmi3.eu/about-nmi3/industry-.html .
NETWORKING ACTVITIES
WP2 – Dissemination and Outreach
Communication is essential for raising awareness of research conducted in Europe’s neutron scattering and muon spectroscopy facilities. One of the goals of NMI3-II was to produce articles and videos that could make its scientific activities and achievements more tangible to non-expert publics.
The website nmi3.eu was an important communication channel among project participants and provides a window to the outside world. Over the years it became a reference to many seeking information about specific neutron techniques.
The website Neutronsources.org which is an initiative of NMI3, was launched to provide information and news on research using neutron beams to a worldwide audience. It is supported by a network of European press officers and thus contains material sent by all neutron sources around the world. There is a page dedicated to each neutron centre and association, news about scientific achievements and events. Those who are new to the field can browse the “Science with Neutrons” page to get to know more about neutrons, their characteristics and applications. Under “Resources” one can learn about projects as well as useful software and tables. On the calendar, you can browse future and past neutron events such as conferences, workshops and schools. Have you got an idea for a neutron experiment? The website tells you the facilities’ deadlines for submission of proposals as well as the operating periods. Are you looking for a job? You might find it on the job tab. The website will remain active after the end of the project.
Collaboration among press officers of large scale facilities is important to go farther in the promotion and dissemination of the science produced in each of the large scale facilities. Efforts were made within NMI3-II to foster these collaborations by organising regular meetings. The workshop “Public Awareness of Research Infrastructures” in June 2015, which was co-organised by the NMI3 Information Manager, was an interesting opportunity to present expectations, experiences and give examples of work on public relations in each facility.
Would you like to know how neutron scattering contributes to advancing science and technology? The European Neutron Scattering Association published a new brochure on Neutrons for science and technology. It highlights typical work of the academic and industrial user communities to illustrate the scope and potential of neutrons. NMI3-II coordinated the publication. The aim is to distribute copies mainly to scientists and students from other fields, in order to attract new users to the technique.
The development of the muon community focussed on themed workshops on functional materials and soft matter, while publicity leaflets and the muonsources.org website have been created with a view to introducing new user groups to muon technique.
WP3 - E-learning, description of the main S & T results
Introduction
Since experimental neutron scattering is mostly restricted to large-scale facilities, not all students have access to learning the technique at their home institution. Providing a freely accessible e-learning portal for neutron scattering is therefore an important outreach task in order to secure and educate the future users and scientists at neutron scattering facilities. This task and challenge has been taken up by the WP3 partners. The collaboration included people from a broad range of disciplines, from didactics and teaching in physics, through neutron scattering in theory, simulation and experiment to programming and web-design. The aim is to offer online teaching material to university students and their teachers as well as scientists from other fields wanting to learn about neutron scattering techniques.
The Platform
To address this teaching challenge, the WP3 partners have developed and utilized an e-learning portal for neutron scattering under the working title “Virtual Neutrons for Teaching” (VNT) – now fully developed with frontpage available at http://www.e-neutrons.org. - See Figure 1 (left).
Figure 1:Left: Frontpage from e-neutrons.org. Right: The tools of interaction between the teacher, student and material in the WP3 e-learning project.
Any learning situation can be schematically described in general terms by the interactions between three parts (topic, teacher and student) in the so-called didactic triangle. In a pure e-learning situation the means of interaction are not the same as in a face-to-face class-room situation; some tools are missing while others are gained. The challenge in any learning situation is to balance the interactions on the sides of the triangle in order to optimise the outcome for every student. During the course of the project, key technical and didactical choices have influenced the platform developments. In Figure 1 (right), we have shown schematically some of the neutron e-learning tools we have developed for the platform and how they fit into the didactic triangle.
Once a user is registered at e-neutrons.org access is granted to the full e-learning platform, made up from three main parts:
A “WIKIbook” provided by Mediawiki with various extensions, e.g. for producing mathematical expressions, playing the role of textbook-material – See Figure 2 (left)
A Learning Management System (LMS) provided by the Moodle system, providing exercises, quizzes and evaluation – See Figure 2 (right)
A web simulator for the McStas neutron instrument simulation program, allowing to perform virtual neutron scattering experiments – See Figure 3
Figure 2 – Left: Textbook example from the WIKIbook - Right: Course material example from the LMS
Figure 3 – Left: Configuration page for a virtual SANS instrument - Right: Simulation output from the same virtual instrument
Learning material
We have designed and implemented 10 neutron scattering modules whereof 8 are general introduction to neutron scattering and techniques and 2 are specialised applications in imaging and magnetic neutron scattering. Two courses are constructed from these modules, basically with the same content, but they differ in learning path restrictions and guidance as one course is intended for student self-study. Whereas, the material in the other can be taken in any order and modules skipped, to fit a course in a blended learning setting.
Using the online simulator that contains virtual instruments with samples, the student can tune pre-defined parameters to obtain synthetic data from Monte-Carlo simulations. The resulting data can be analysed like real, measured data. In quiz-lessons connected with some of the instruments the students can explore through theory and virtual experiments, how a neutron scattering technique is used to solve a scientific problem. These quiz-lessons are constructed with the advanced Moodle quiz module which has been used to implement many types of quizzes ranging from student self-tests which can take some minutes up to an hour or two for students to complete, to stand-alone learning modules which take several hours to complete.
Background reading material is made available through the WIKIbook and contains written material and exercises adapted and reworked from coherent and progressive lecture notes collected in an (otherwise unpublished) book by several authors, but with main author and moderator Kim Lefmann.
The tools in the e-learning platform have been thoroughly tested as they were developed in blended learning settings i.e. class-room courses with supplementary material in the e-learning platform. A total number of about 150 students have participated in the tests, mainly in face-to-face courses held in Denmark, Germany and Sweden. User comments in e.g. quiz-replies and focus group interviews have been used to iterate the contents of each module of the courses as well optimise the learning material and activities.
Interoperability of the different software used in the e-learning platform has been ensured through an LDAP based tool developed within this project which from the entry page http://www.e-neutrons.org handles the user account creation and login to each of the three software programmes with the same credentials.
The neutron community are invited to contribute material from schools, pedagogical review papers on methods and techniques, books on neutron scattering which are no longer in print, handbooks and multimedia material via the Library, which is currently implemented as part of the Moodle LMS and upload rights will be granted on request. We have uploaded some key examples as part of WP3. The provision of established books, however, is limited by copyright restrictions. Open source material from schools organised in NaMES (see WP4) and international schools will we added as they become available.
WP4
The achievement is the creation of a distributed Training facility called NaMES - Neutron and Muon European Schools. Collective announcement of a series of schools (brochure and website) ensures their successful occurrence and the refinement of overall interaction and organisation of the schools in the series. Over the four years 17 schools have received support for travel and subsistence cost of the students by NMI3-II. Roughly 1500 students have been supported via the project and hence been made aware of NMI3-II.
The School directors had to provide a detailed financial report in order to make sure that the support is dedicated only to travel and subsistence for students and in special cases for lecturers (in Eastern European countries). All school have put in place a satisfaction survey. The exploitation and hence improvement measures to be taken are in the remits of the respective school organiser.
The NMI3-II Advisory Committee (AC) conducted the first evaluation of the schools in the beginning of 2013. According to this evaluation the schools were judged to be broadly successful. However, in order to attain high, shared standards, recommendations for improving future evaluations of schools have been made. The School reporting rules were refined (WP1) in order to assure a sound assessment of the financial support compared to the total cost of the schools.
The first NaMES schools directors’ Synergy Workshop was in Berlin (June 2013), the second NaMES meeting (September 2014) was held in Zaragoza - both satellites to the NMI3 General Assembly. These meetings brought together all schools’ directors, some AC members and the NMI3 management. They provided an invaluable forum of discussion for school organization within the NaMES umbrella.
Synergies with the E-learning work package (WP3) have been identified and materials provided.
WP5
Easy and open access to large scale neutron and muon facilities by national and international external scientific users is a general mission of all such public-funded scientific institutions in Europe. Unfortunately the fragmentary structure of the individual user access at the various facilities has been identified as a possible obstacle for the growing user community in Europe. Also, the facilities with large numbers of proposals (e.g. more than 600 per year at TUM) need to spend increasing amounts of time and administrative resources in organizing this task. New large facilities such as the European Spallation Source “ESS” with potential high throughput beam lines may deal with even more severe administrative efforts.
Facing these challenges, of increasing user demand and fragmented access structures, the following objectives have been successfully achieved. The eleven partner facilities offering open access to users, did work in mutual agreement on the tasks defined according to the five objectives, each task being led by one partner.
Development of a generalized integrated user registration. Technical and legal requirements for a common NMI3 based single electronic user ID to access individual facility digital user office (DUO) systems will be analyzed and the best possible solution will be evaluated and established as a prototype. (Task 5.2)
Harmonized proposal forms and templates. Forms and templates of proposal submissions at existing DUO applications will be compared and a harmonized proposal template adopted for the individual requirements will be proposed and prepared for implementation. (Task 5.3)
Web based proposal peer review process. A framework will be developed to allow peer reviewing of submitted proposals within NMI3 web applications for small facilities, which do not operate an individual DUO. (Task 5.4)
Platforms for cross-source independent beam time access. Platforms to submit proposals for access by the combination of instruments at the NMI3 facilities and platforms for cross-source proposals for the complementary use of instruments, laboratory services or infrastructures using different probes (e.g. neutron, muons, x-rays, facility based AFM or electron microscopy) will be considered and developed. (Task 5.5)
WP6
A clear overview on the existing software landscape for neutron/muon scattering has been established as most of the available neutron and muon software has been identified and evaluated. These have been gathered in a Live DVD, which facilitates software use and testing. The practices employed to develop and maintain the software have been analysed to define a set of recommendations to be used in further projects. The criteria used for the software review are deployment, installation, usability, functionality, maintenance and extendibility. The criteria used for the software practices are related to version control, points of failure, testing, documentation and code duplication.
Among currently developed software, special focus has been given to the Mantid project, which has been developed recently for spallation source instruments at ISIS and SNS. It is investigated to what extent this framework can be used for instruments based at continuous neutron sources. To evaluate the effort required to deliver such functionality, new data loaders have been successfully written for the time-of-flight spectrometers IN4, IN5, IN6 at ILL, MiBemol at LLB, and Focus at SINQ/PSI. A set of existing data treatment algorithms, already available in Mantid, was used, and results were compared satisfactorily with those e.g. of the LAMP software.
A loader for the D33 SANS instrument at ILL was also written. The McStas software was upgraded to write NeXus files readable by Mantid, to account for any virtual instrument model geometry. However, implementing loaders for scanning instruments tends to be more complex in the current Mantid framework. The team will continue investigating beyond the project. Even though the Mantid software provides extensive functionality, some complex and very specific new features may have to be developed as separate, specialized software components.
All deliverables have been published on the NMI3-II web site http://nmi3.eu/about-nmi3/networking/data-analysis-standards.html and are available to the public, including the produced source code.
JOINT RESEARCH ACTIVITIES
WP17 - Muons
Software Development for Muon Data Analysis
Early in the project we looked at common data analysis procedures, highlighting a requirement for new data analysis tools for processing Avoided Level Crossing spectra, and for carrying out phase-quadrature and rotating reference frame transforms (Fig. 1). These codes were released under the Mantid framework and are now in regular use by the user community.
A parallel study considered how simulation codes might be exploited during data analysis. The ‘Quantum’ package for the simulation of muon spin evolution using the density matrix method was refactored as Python subroutines for execution within the Mantid framework. A number of case studies were developed to illustrate the scope and flexibility of the code (Fig. 1). The potential for using ab initio Density Functional Theory methods as an aid to interpreting Avoided Level Crossing spectra was also investigated. Molecular couplings for an example muoniated system were calculated, and used to explore methods for refining these values obtained from simulation. The work demonstrated that further development was required before the technique can be reliably used as a predictive tool in experiments.
Figure 1: Workflow for analysis of Avoided Level Crossing data (left), a Rotating Reference Frame transformation of muon spin rotation data (centre) and data modelling carried out using the ‘Quantum’ package.
Concept Studies for Future Muon Sources
Early discussions with Prof Bob Cywinski, a member of the University of Huddersfield’s International Institute for Accelerator Applications, led to an extended study of target technologies for muon production. The collaboration developed, with Prof Cywinski hosting at a workshop January 2015 (Fig. 2), which brought together facility staff, accelerator scientists and facility users to consider the requirements for next generation muon sources and the scientific problems they might address.
A concept study to investigate the feasibility and research potential of a muon micro-beam (Fig. 2) was also developed as part of the project. The work considered the possibility of carrying out µSR experiments on ~100µm samples, the potential for scanning the sample to investigate inhomogeneities and the possibility of completing parallel measurement of several micro-samples. Very promising results were obtained, with results suggesting a facility could develop a practical micro-beam with relatively modest resources, with greater intensities being possible in the future using more sophisticated focussing and slit systems (akin to electron microscopy).
Figure 2: Attendees at the Future Muon Sources workshop (left) held and the University of Huddersfield, and beam transport modelling for a study investigating the feasibility of producing a muon micro-beam.
Detector Technologies for Pulsed Muon Sources
Avalanche Photodiodes (APDs) had previously been shown to provide excellent timing resolution that was invariant with magnetic fields. However, their ability to measure the very high instantaneous rates inherent to use at a pulsed muon source was not established. Work within this project developed a systematic study of the performance and operating parameters of APD-based detectors (Fig. 3), enabling the dead time to be properly characterised and compared to equivalent PMT-based systems.
Tests quickly established that the baseline performance of APDs at very high data rates was not ideal because of their extended recovery/dead time (Fig. 3). However, increasing the pixelation greatly improved performance, and further gains were realised by differentiating device output signals before acquisition. For an optimised system, a performance comparable to a photomultiplier-based detector has been realised; however, further work is needed to demonstrate their suitability for building the high density arrays presently being planned for the MuSR and HiFi instruments at ISIS. A fruitful collaboration is developing between the muon groups at the ISIS and J-PARC pulsed sources, with useful discussions ongoing as to how to make best use of these devices in this environment.
Figure 3: APD test devices assembled within a light-tight enclosure (left) and signals measured for SensL APDs, comparing the response of the slow (centre) and fast/differentiated outputs. The extended recovery, particularly for the slow output, is immediately apparent.
WP18 – Neutron imaging
Nano- and micro structures resolved dark-field neutron imaging with grating interferometers (nGI) New set of gratings was manufactured at PSI and TUM (1a). The new gratings allow for increased visibility contrast and therefore for improved performance of the nGI-setup (1b,c). A compact water-cooled 0.4 T electromagnet (1d) was constructed at PSI in cooperation with TUM. To minimize the influence of the magnetic field on the grating setup, the magnet is strongly shielded. A modification of the field distribution inside the magnet is possible by an asymmetric operation of the coils which changes the homogeneous field inside into a distorted configuration. A new nGI setup at ANTARES imaging beamline at FRM-II was constructed with a possibility to rotate all gratings simultaneously around the neutron beam (1b,c). Hence, by an evaluation of the dark-field contrast variation as a function of the rotation angle of the gratings, it is possible to detect anisotropy directions within the microstructure of a sample (1e).
a b c d e
Figure 1. a) new gratings manufactured at TUM; b)c) photos of the new nGI setup at the ANTARES instrument (FRM-II); d) new magnet constructed at PSI; e) anisotropy in the microstructural properties of the materials (bottom - Gd µm-grating , middle - copper rod, right - fiberglass material) measured by nGI.
Direct high resolution neutron imaging
The high-resolution neutron imaging test arrangement is currently being developed at NIAG, PSI in collaboration with HZB under the project entitled “Neutron microscope” (2a). The goal of the project is to develop and implement a dedicated optical system that would allow neutron imaging experiments with spatial resolution below 5 micrometres and within reasonable exposure times. The key element is the development of new high-resolution scintillator screens. Two distinct ways are being followed up– (i) very thin diffuse scintillator based on Gd substances (e.g. Gd2O2S:Tb3+) and (ii) micro-structured scintillator screens based on Gd substances (2b). A magnifying optical system was developed. The optical design of the lens has been performed and the first tests were carried out (2c,d). A prototype of new high resolution neutron detector system (2a) at V7/CONRAD-2 instrument at HZB made possible to reach spatial resolution of 15 µm in radiographic images. The optimized detector system opened the possibility of performing tomography experiments (2e) where several hundreds of sample projections are recorded .
a b c d e
Figure 2. a) high-resolution detector at HZB; b) diffusive (top) and micro-structured (bottom) scintillators; c) high-resolution detector setup at PSI; d) high-resolution neutron image with pixel size 1.5 µm; e) high resolution neutron tomography of hydrogen embrittlement in iron (red=hydrogen).
Energy-selective neutron imaging
A new energy-selective setup (3a,b) was designed and installed at the neutron imaging instrument CONRAD2 at HZB. The obtained wavelength resolution is in the range of 3 %. The wavelength of the output monochromatic beam can be tuned continuously in the range of 1.5 Å – 6 Å. The setup was used for nondestructive 3D mapping of crystallographic phases within the bulk (centimeter range) of samples with micrometer-scale resolution (3c). The Bragg-edge mapping using continuous neutron sources was extended to Time-of-Flight (ToF) technique on pulsed sources (3d).
a b c d
Figure 3. a) double-crystal monochromator installed at the CONRAD-2 instrument at HZB; b) photo of the device; c) Bragg-edge mapping of TRIP steel – 3D crystallographic phase separation; d) Bragg-edge analysis of crystallographic phases in steel by using double crystal monocromator (top) and ToF method (bottom).
SANS 3D: vectorial magnetic imaging of nano-objects
Polarized SANS measurements have been performed on various systems such as: (i) carpets of Co nanowires deposited on a sapphire substrate (4a), (ii) regular arras of magnetic nanowires deposited in alumina membranes, (iii) aggregates of Co nanowires synthesized by the polyol process (4b). For these different systems Nmag software tool was used to perform micromagnetic simulations (4c,d).
a b c d
Figure 4. a) Carpet of Co nanowires with the SANS scattering signal; b) aggregates of nanowires with the SANS scattering signal; c,d) Modeling of these systems using micromagnetic simuations of large arrays of nanowires.
Precession techniques for imaging magnetic structures in thin film systems
Very narrow beams in were produced by using either a silicon reflector (5a) or a neutron wave-guide so that a neutron beam can be scanned across the magnetic wire (5b). Simulations help for data analysis (5c).
a b c
Figure 5. a) Micro-beam (20 µm) produced by using a reflection system; b) Neutron precession measurement through a magnetic micro-wire; c) Simulation of a precession measurement through a magnetic microwire.
WP19 Advanced Methods and Techniques
Sub-mm3 samples for extreme environments
The focusing optics for the upgraded ILL IN5 instrument has been optimized via numerical simulations (McStas) and a particle swarm optimization algorithm appropriate for noisy problems (iFit library). The results confirm that a multi-channel guide is not necessary (Fig. 19.1). For the ThALES 10T magnet entrance channel a focusing guide element has been optimized by a Monte Carlo method (SimRes). The best guide for optimizing the flux at the sample position turned out to be a linear tapered shape.
Figure 19.1: Right: vertical profile of the best three-channel guide found for IN5. Middle: performance of a focusing guide element of the ThALES 10T magnet. Right: schematic view of the multipurpose instrument devised for extreme conditions-
The conceptual design of three extreme condition instruments has been achieved. A) A multi-purpose instrument (Helmholtz-Zentrum Berlin) which operates in three modes: diffraction, spectroscopy, and SANS. Such multi-functionality is achieved by a proper design, which consists of a bi-spectral moderator, for cold and thermal neutrons, with a specially designed extraction system; a transport system that incorporates a chopper cascade; etc. Numerical simulations (VITESS) show that its performance and compares favourably with that of existing instruments. B) XtremeD, optimized for high pressure and/or high magnetic field. C) EXPRESSO, a neutron diffractometer optimized for high pressures and the long pulse characteristic of the ESS, will deliver high fluxes at both long and short wavelengths.The design allows direct access to the sample position, and the incorporation of optical probes for in situ pressure measurement (by ruby fluorescence) and ancillary Raman spectroscopy. This set-up also enables a laser heating arrangement of the type used at many synchrotron beam lines.
Spin Echo with Oscillating Intensity for ESS
This joint-research-project is devoted to adaption of the MIEZE technique running on reactor-based instruments like MIRA und RESEDA at the FRM II to the needs of pulsed beams. New resonant spin flipper coils to achieve higher frequencies (resonant spin flip at f = 3.45 MHz) and therefore a higher resolution have been tested (Fig. 19.2). Problems with high currents have been addressed.
Figure 19.2 Left: the resonance circuit used for NRSE and MIEZE. Middle: (a) conventional coil design used in transversal and longitudinal NRSE; (b) simple coil with low inductivity used for tests. Right: scan of static field B2 at fixed current through resonant flipper coil.
The CASCADE system detector was evaluated, modified and tested for accepting a chopper signal from either a chopper or a synchronization pulse from a pulsed neutron source. Tests were performed at the reactor instruments MIRA and RESEDA of FRM II and at the pulsed beam line CG-1D at HFIR, Oak Ridge National Laboratory (ORNL). The design for the data acquisition and the fitting procedure tested in the pulsed beam line can be clearly chosen as the standard measurement strategy for the planned longitudinal MIEZE spectrometer at ESS. A test of a spin-echo modulated small angle scattering has been successfully performed in the Larmor instrument of ISIS, confirming that there are no significant difficulties in synchronising data collection to the ISIS pulse and no unexpected additional problems.
Choppers for the ESS instrumentation
A chopper concept has been studied with a small high speed motor connected to the rotor by means of an elastic shaft. The system stability at high rotation frequency has been analysed by finite element calculations. The neutronic properties of a single chopper and of a chopper array have been analyzed by means of computations. A (scalable) chopper array with 1% overlapping has been devised which provides the appropriate neutron suppression. Undesirable effects as the suppression of slow neutrons at high rotation frequency have been studied and solutions proposed.
Figure 19.3: Left: picture of the system with labels for the components; Center: test stand for mechanical rotor assessment and the drive electronics rack; Right: results of the stability analysis at high rotation speed.
Polarising all neutrons in a beam
The configuration (Fig. 19.5) is a combination of a neutron polarizing and a neutron transport system, in which both neutron spin states (├ ├|↑┤⟩ or ├ ├|↓┤⟩) can be separated, manipulated and re-combined to a beam that can be used for polarized neutron scattering experiments. A super-mirror polarizing cavity comprising two super-mirrors arranged separates the incoming neutron beam into three beams. The lateral beams have polarizations opposite to the central beam. A broadband spin flipper flips the spin state of the neutrons in the central beam. Then the three neutron beams are recombined at the central position of a neutron scattering instrument. Monte Carlo simulations (VITESS) show that the setup has high performance over a broad range of the relevant parameters.
Figure 19.4: Left and center: schematic view of the device. Right: normalised neutron intensity (a), polarisation (b), horizontal beam profile (c) and divergence (d) of the system for three values of the angle θ for the polarising cavity.
WP˗ 20 Advanced Neutron tools for Soft and Biomaterials
A Platform for model biological membranes
After extraction, purification and analysis of natural lipids from the biomass produced from protein deuteration at the D-Lab facility at ILL, a few neutron reflectivity studies of biomolecules at the surface of natural or deuterated lipids membranes have been then performed. Besides, the method for creating unconstrained, deposited biomembranes on the top of a chemisorbed Self Assembled Monolayer (SAM) of phospholipids on a substrate producing reliable SAM’s of effectively 100% coverage is now regularly used as a sample-environment option for user experiments. Significant progresses have been made in the incorporation of Molecular Dynamics calculations for the interpretation of neutron reflectivity curves. Complex membranes from lipids mixed with proteins or peptides, natural ore deuterated, can be better studied by neutron reflectometry thanks to these novel tools, labelled biomaterials and methods.
Kinetic/dynamic measurements in periodic external fields
A new design of observation head for stopped-flow (SF) device has been achieved, allowing a reduction (40%) of the sample volume, and the use of Hellma© cells of different neutron paths. Improvement of the quality of mixing thanks to a new damping grid combined to an automatic push and pumping system (tested) would decrease the duration of mixing and allow measurements of first steps of kinetics after mixing. The SF device, shown in Figure 1, now provides the ability to control the temperature inside the head independently from the temperature of the bath before mixing liquids, and isolates the cell from environmental temperature variations.
A multi-angle dynamic light scattering setup is definitely installed on the Small Angle Neutron Scattering (SANS) spectrometer KWS2 at JCNS. It can be combined with an external commercial static light scattering instrument.
Figure 1.Photograph of the new thermalized observation head mounted on the stopped-flow system at ILL.
Design and photograph of a thin walled TiZr pressure cell suitable for high scattering angles optimized for NSE experiments, tested up to 460 MPa for an operation pressure up to 400 MPa. Design of a thermalized electric field cell prototype with electrodes outside the sample in a quartz cell.
Various prototypes of pressure devices for SANS and Neuron Spin Echo (NSE) have been tested and developed during the project. A thin walled TiZr pressure cell dedicated to NSE experiments will allow reaching 400 MPa (see Figure 1) on large sample area (3*3 cm2). A TiAl6V4 alloy has been validated as a good material for high performance pressure cell windows (up to 700 MPa in SANS). Design of a separation chamber between the pressure fluid and the sample has been validated up to 700MPa. From experience gained on one prototype with sapphire windows tested up to 450 MPa and validated up to 330 MPa, three versions of pressure cells with sapphire win dows are foreseen: one for NSE experiments up to 50 MPa for 30mm diameter sample’s area and two for SANS experiments, up to 500 MPa (with a compromise with respect to the available opening angle or a beam size (intensity) reduction) and up to 300 MPa (without compromise).
Simulations using Finite Element Methods software, COMSOL® Multiphysics, of electric field and air flow have been performed at LLB in order to build a thermalized electric field (EF) cell with electrodes out of the sample cuvette (see Figure 1). The cell body and the sample chamber of a second prototype of EF cell built during the project are made from PLA by 3D printing. On assembly, the cell was tested successfully with various usual solvents; measurements and simulations of electric field have been compared. Feasibility of thermalization by a simple stream of temperate air flow has been demonstrated.
Humidity chamber
Considerable and collaborative efforts at HZB and ILL have focussed on the design of a humidity cell with a factor of 5 improvements in humidity (i.e. temperature) stabilization. After series of tests on a first prototype chamber in 2014, a second improved version was produced in 2015 (see Figure 2). Highest precision in humidity control is achieved from 0% to 99% relative humidity (r.H.) on both prototypes; special options using Peltier elements (see Figure23) and temperature regulation for fast sample equilibration are required to reach 100% r.H. saturation. The prototype BerILL 1.0 is in HZB user-office since October 2015.
Figure 2. Humidity chamber BerILL 1.0 at HZB and BerILL 2.0 at ILL Grenoble. Base design of the sample stage with mini goniometer for sample alignment. Peltier to control sample holder T° for highest humidity applications.
Cryogen free cryostat
A compact and modular cryogen-free cryostat was built with a separate sample space isolation vacuum and a cold head isolation vacuum, allowing the cold volume to be minimized (see Figure 3). Thermal coupling to the cold head is achieved by heat switches to realize fast cool down and warm up. Some elements have been modified after temperature tests. A standardized sample holder providing a pin connection for thermal link and thermometry facilitates sample change and interchange. The sample storage and a robot for sample handling are foreseen to be located at room temperature.
Figure 3. Cryogen-free cryostat: drawings and picture.
WP21 – Detectors
Scintillation detectors
For the scintillation detectors ISIS and Jülich have each developed detectors using ZnS:Ag/6LiF scintillator. The detectors use wavelength shifting (WLS) fibres and multi anode photomultiplier tubes MaPMTs. Different fibre coding, electronics and signal processing have been developed. The final ISIS and Jülich demonstration detectors, shown in Figure 1, have been evaluated. Neutron detection efficiencies and position resolutions can easily be adapted to meet a wide range of applications. The demonstration detectors developed are modular, easy to construct and provide a means of covering large areas in a cost effective manner.
Figure 1. LHS and LC: ISIS WLS fibre demonstration detector. RC and RHS: Jülich WLS fibre demonstration detector.
CNR/Perugia has explored the potential of SiPMs for reading out large area neutron scintillation detectors. A system has been developed using up to 7.5 x 7.5 mm2 GS20 glass scintillators coupled via Plexiglass light guides to a 3 x 3mm2 SiPMs, see Figure 2. Scalable electronics has been designed and produced and a pulse shape analysis routine has been developed to identify neutron pulses.
Figure 2. LHS: Test detector with SiPM connected to GS20 glass scintillator with straight light guides. LC: Pulse height spectrum from a SiPM connected with straight light guide. RC: Four 3 x 3 mm2 SiPMs mounted on stackable electronics. RHS: Four tapered Plexiglass light guides coupling GS 20 glass scintillator to four SiPMs
Gas detectors
One of the major challenges in developing gas detectors based on solid 10Boron is the need to deposit 10Boron based layers of ~ 1 µm thickness over large areas. To assess coating quality, TUM and BNC evaluated the performance of 10B4C coatings from a number of different manufacturers produced by both magnetron sputtering and electron beam evaporation, see Figure 3. TUM developed a test detector specifically for this task. Magnetron sputtering is now the accepted standard method of producing 10B4C layers. HZB have studied alternative and potentially faster processes for depositing 10Boron based coatings. They have identified powder spray deposition with a high temperature atmospheric plasma torch as the most promising alternative technique. An experimental system has been developed as shown in Figure 3. A 2D-position sensitive detector has been developed by HZB and BNC to evaluate the quality of these coatings, which is also shown in Figure 3.
Figure 3. LHS: Examples of some of the 10Boron coatings evaluated. LC: The Microwave Atmospheric Plasma System at HZB. RC: The plasma jet after 10Boron powder injection. RHS: The 2D detector constructed by BNC and HZB.
TUM have investigated the “grooved” converters, see Figure 5, in order to reduce the number of 10B4C layers required in a detector, whilst maintaining high neutron detection efficiency. Results show that an increase in detection efficiency of up to ~50% is possible with this design. TUM have developed a concept for a large area gas detector based on these “grooved” converters and multiwire proportional chambers, MWPCs. The concept detector, shown in Figure 4, has an active area of 40 x 40 cm2 and consists of two MWPCs and four grooved converters. This concept will be developed further by the ESS.
Figure 4. LHS: Schematic cross section of a “grooved” converter. C: The large area gas detector concept based on “grooved” converters and multiwire proportional counters. RHS: photograph of the concept detector based on a micromegas amplification structure.
CEA have developed a concept for a large area gas detector based on thin meshes coated with 10B4C on both sides and a bulk micromegas amplification stage. The concept has been extensively simulated to optimise critical construction parameters, operating conditions and neutron detection efficiency. A detector with an active area of 54 x 54 mm2, shown in Figure 4, has been designed and built to test out this concept.
Potential Impact:
WP1 – Management
NMI3 as a whole can be expected to have a significant socio-economic impact. Neutron scattering and muon spectroscopy are key experimental techniques in the design and characterisation of new materials and processes. Up to two-thirds of neutron and muon experiments can be considered as being directly or indirectly related to materials and processes with potential applications, while in some facilities, close to 20% of beam-time is funded directly or indirectly (via research groups) by industry. Dissemination, outreach and education (WP2 & 3) are therefore indispensable activities with respect to future socio-economic impact. Harmonising access procedures for facilities and improving access to scientific results through improved software (WP5 & 6) will encourage new neutron and muon users, including industry with its specific requirements in terms of timely production of relevant scientific results.
More specifically, of the JRA’s, WP18 is developing neutron imaging techniques, benefitting from the unique properties of the neutron, which are analogous to well-known X-ray and microscopy techniques, and should therefore have significant impact. Similarly, WP20, focussing on soft and bio materials, will develop tools that will significantly enhance research capability, ultimately contributing to societal challenges in the health domain. Finally, the detector technology developments in WP21 could potentially be transferred to a number of companies manufacturing radiation detectors.
WP2 – Dissemination and Outreach
Communication is essential for raising awareness of research conducted in Europe’s neutron scattering and muon spectroscopy facilities. One of the goals of NMI3-II was to produce articles and videos that could make its scientific activities and achievements more tangible to non-expert publics.
The NMI3 website remained very important for the whole duration of the project as it offers useful tools to all project members. Everyone part of the scientific community, general public and policymakers can learn about the project achievements, partner facilities and other relevant information. The dissemination of the project’s scientific achievements contributes to raise awareness about the importance of neutron and muon research among diverse audiences. We publicised the scientific possibilities of these techniques in order to increase the number of users. We have in fact observed a growing number of subscriptions to our website and newsletter, and have received positive feedback from scientists worldwide e.g. via online social media (e.g. LinkedIn and Twitter). Furthermore we have come to notice that a number of external websites like e.g. Phys.org Horizon, have published news items about the project’s activities and results.
Regarding the independent website Neutronsources.org it is our objective to turn it into a sustainable reference website for the neutron community worldwide. A steadily growing number of institutions contributing to its content, indicates that we are on the good way to reach our goal. The development of the muon community has focussed on themed workshops on functional materials and soft matter, while publicity leaflets and the muonsources.org/ website have been created with a view to introducing new user groups to muon technique.
Collaboration among press officers of Europe’s neutron and muon facilities is important to go further in the promotion and dissemination of the science produced in each of the facilities and within the project. The NMI3 Information Manager thus coordinated meetings as well as an international workshop with press officers in order to foster collaboration and to achieve a sustainable communication network. Given the success of these events, future meetings are already being planned.
WP3 – E-learning
The online distribution of e-learning material on neutron scattering through http://www.e-neutrons.org and the development of a full introductory neutron scattering course which is freely available will make an important contribution to expand the neutron user community due to several factors: Students and researchers at universities without connection to local neutron scattering courses and/or without funding to travel to the limited-seat hands-on courses can by their own choice and on demand, comfortably complete a full 8-week undergraduate training programme, or briefly familiarise themselves with a particular technique in order to assess whether it will be useful for their research projects. Both factors will ease the entry into the neutron scattering community, and online availability will increase visibility world-wide, also at smaller universities. Furthermore the innovative use of virtual experiments for training, which is openly available and easily accessible through a browser, can be utilised also for existing face-to-face neutron schools (as part of blended learning), thus helping students connect theory with experiment and maximising the outcome of the limited hands-on training which is available at the neutron facilities.
WP4 – European Neutron and Muon Schools (NaMES)
More than 1500 European early career researchers received training via the NaMES schools since the start of the project. This training is of immense value to the Neutron and Muon science communities, providing, in many cases, access to instrumentation at central facilities in a training and learning environment. This WP will continue to ensure that the European neutron and muon schools continue to improve their output by regular exchange of information and coherent organization and publicity. A follow-up of the future career paths of those trained under the NaMES programme has not been done so far, but school directors state that the students create groups in the different social networks.
WP5 – Integrated User Access
The work done in WP5 has stimulated further studies of harmonized proposal forms and procedures between the neutron and muon facilities. With the demonstration of software package prototypes to handle harmonized proposals and review procedures, it can pave the way to an easier and more straightforward access to the facilities and allow users to interact with the neutron and muon facilities within a common framework for integrated user registration, including cross-facility, beam time access. Results of the WP contain the basis for next steps to implement harmonized proposal forms and administrative processes within the next TNA project of the neutron and muon facilities.
WP6 – Standards for Data Analysis Software
This work-package aims to show that a common software solution can be shared across neutron/muon facilities. The chosen solution, here Mantid, has been used as a prototype infrastructure for this purpose, but other initiatives with similar standards could also be envisaged. Our reports and produced code can be used by any group producing scientific software, and more specifically in the neutron/muon user community. Scientists in the EU can benefit from a shared solution by lowering the learning curve when travelling across facilities. It is hoped that a well-designed, unified software can help to attract more scientists to neutron/muon facilities.
WP17 – Muon Spectroscopy JRA
Key analysis routines identified through JRA work have been implemented; codes, such as a GUI for the analysis of Avoided Level Crossing measurements, are now in regular use at the facilities. Data analysis methods that create a link with simulation codes have been investigated, with a number of examples (such as the quantum mechanical evaluation of spin systems) being developed. Activities in this first task area have made it easier for scientists to extract key results from their data. Discussions at the ‘Future Facilities’ workshop are already proving valuable for opinion forming by those considering funding for new muon facilities, whilst the positive outcome from the concept study for a muon micro-beam could lead the future development of a novel µSR facility. The evaluation of APD-based detectors for pulsed muon sources is particularly opportune, as a design study is currently underway to develop a next generation high density detector array for the MuSR instrument at ISIS.
WP18 – Imaging JRA
Through this research and development activity, new techniques and modelling tools will be made available for a large number of users from the large communities of the nano-magnetism, engineering and generally from materials science.
This project is developing new methods which can provide information on material and magnetic systems which are not accessible using any other experimental technique.
External laboratories (besides neutron facilities) are already involved in the developing and optimizing of the new techniques in respect to their needs for tackling actual scientific problems.
WP19 – Advanced Methods and Techniques JRA
The software to optimize neutron guides depending on many parameters has been developed and tested. It will allow to find the optimal design of the optics for focusing onto sub mm3 samples under extreme conditions of novel neutron instruments in an efficient way. Simulations of the performance of optimized multi-channel guides for the ILL instruments IN5 and ThALES have been performed. They will allow to take a decision about the optics to be implemented in these instruments. The conceptual design of three instruments for extreme conditions neutron experiments has been achieved: first, one for pulsed sources, versatile, capable of operating with short and long pulses and in three different modes (diffraction, spectroscopy, and SANS); second, XtremeD, devised to work at high pressure and/or high magnetic field at constant sources, will be built at ILL; and third, EXPRESSO, an instrument optimized for high pressures and the long pulse characteristic of the ESS. The instruments will provide extreme conditions scientists with superb tools for their research. Particularly, EXPRESSO should be built at the ESS, where it could optimally exploit the TOF technique and the long-pulse structure. Calculations have shown that such an instrument would deliver dramatic increases in flux, particularly at longer wavelengths.
The MIEZE technique was extended to the use with pulsed sources using an improved electronic control for adopting the MIEZE signal to the pulse length of the source. This allows for the measurement of the quasi-elastic dynamics over a large q-range at the same time contrary to the current used method on reactors where one needs measure the dynamics at different q-values sequentially. This development, which has been tested on a chopped beam of neutrons from a reactor, allowed for the successful proposition of a combined NSE and LNRSE MIEZE instrument for the ESS in Lund. The concepts for new RF coils developed within this project as well can be used to operate such an instrument at much higher frequencies as in current instruments and will eventually lead to the construction of a very powerful and flexible high-resolution Spin Echo Instrument.“
The new chopper array concept for focusing neutrons both in space and time in pulsed sources was developed. The elaborated design rules and identification of critical points of operation as well as identification of limitations in neutronics will in future allow to have a quick start in planning and building of a multichopper system for novel use in chopper instruments. Currently there is no concrete project known, however, illuminating the possibility shows ways towards novel focussing schemes in time and space that can be used in future innovative neutron time-of-flight instruments.
Polarised neutron beams are used in disciplines as diverse as magnetism, soft matter or biology. However, the existing neutron polarising methods imply the filtering of one of the spin states, with a transmission of 50% at maximum. With the purpose of using all neutrons that are usually discarded, we have investigated by means of Monte Carlo simulations a system that splits the neutron beam according to their polarisation, flips them to match the spin direction, and then focuses them at the sample. The simulations show that this is achievable over a wide wavelength range and with an outstanding performance at the price of a more divergent neutron beam at the sample position.
WP20 – Advanced Neutron Tools for Soft and Bio Materials JRA
Soft and bio materials have potentially very high socio-economic impact. Lipid membranes are a core material in this area and significant progress is being made in the intrinsic quality of these samples and their deuteration which enables neutron techniques to provide unique information. Molecular dynamics simulations combined to contrast enhancement techniques give key insights into these experimental studies.
The rate at which samples can be measured and the range of experimental conditions are also crucial to the relevance and effectiveness of experimental studies. New sample environment equipment has therefore been developed in this context: an improved stopped-flow device to study kinetic effects, a combination of in situ light scattering and small angle neutron scattering (SANS) to be able to study a broad range of structures of complex samples, an electric field cell with electrodes out of the sample cell, a humidity chamber to study the hydration of lipid membranes up to 99% humidity, various pressure cells optimized for SANS and Neutron Spin Echo techniques and a sample changer in a cryogen-free cryostat to allow efficient measurements of many samples over a wide temperature range.
WP21 – Detectors JRA
The expected result of this work is the development of two new neutron detector technologies suitable for large area neutron detectors for neutron scattering applications. In the absence of sufficient quantities of 3He at an affordable price, new detector technologies are an essential requirement for both new and existing neutron scattering facilities to realise their full scientific potential. The work carried out at these facilities maps directly onto the European science programme which is addressing concerns including climate change, health care, energy, food safety and security.
List of Websites:
http://nmi3.eu/
The Neutron and Muon Integrating Infrastructure Initiative – NMI3 – brought together 18 European partners, of which 8 are neutron sources and two of these are also muon sources. NMI3 was structured in three strands: networking activities (NA), joint research activities (JRA) and trans-national access (TNA).
In such an extensive collaborative activity, communication was a primary need, both within and beyond the project - the NMI3 website (nmi3.eu) provided this important communication channel. In addition the international neutronsources.org and muonsources.org portals have been launched in order to assure project-independent sustainability for the scientific community. Particular emphasis was given to promoting the less well-known muon technique to the wider scientific community.
Training students and young scientists in the area of neutron scattering is vital for sustaining neutron and muon based research in Europe. For these experimental techniques, which are restricted to large-scale facilities and may therefore be largely unknown in home institutions, training is particularly important. Based on state-of-the-art IT and best didactical principles, htttp://www.e-neutrons.org provides a freely accessible e-learning portal for neutron scattering for students from bachelor to PhD level as well as researchers who are not regular neutron users. A dedicated full introductory course has been constructed for master-level physics students.
NMI3 supported the distributed training facility NaMES for neutron scattering and muon spectroscopy in Europe. NaMES served about 1500 students over the four years’ period, but hands-on exercises remain still limited and e-neutrons is a very welcome tool to support the NaMES activities and teach more users.
In order to organize access of scientific users to European, large scale neutron and muon facilities, an integrated access format for scientific users has been developed with harmonized proposal forms and optimized peer review processes and demonstrated in a software prototype.
After the experiment, data has to be analysed. The existing, uncoordinated approach to data analysis results in widely varying standards, different user experiences at each facility and single-points of failure in software provision. An analysis of the existing software landscape and coding practices was the starting point of the data analysis networking activity which proposed a set of recommendations for a common European e-infrastructure.
Work associated with the Muon spectroscopy focussed on developing state of the art data reduction, new source technologies and improved detectors to enhance the potential of the technique. New algorithms, together with a link between analysis and simulation codes, provided the user with improved methods for data analysis. Concept studies centred on improved targets, advanced micro-beams and high intensity sources helped the community plan future facility upgrades. Avalanche Photodiode (APD) based detectors have been developed and evaluated for measuring the high instantaneous rates inherent to the pulsed muon beam at ISIS; this work will point the way for the development of future high density detector arrays at the facility.
Neutron imaging is a direct method for non-destructive visualisation of objects in science and technology. Innovative methods have been developed combining real space with reciprocal space approaches and probe micro and nanostructures in bulk materials. The magnetic moment of the neutron allows two- and three-dimensional visualization of magnetic field and domain distributions.
Advanced methods and techniques for neutron experiments at the future European Spallation Source (ESS) have investigated new instrument designs and sample environments. Prototype development in the field of extreme environments, Neutron Spin Echo with oscillating intensities, choppers and polarisation of the totality of the neutron beam for long-pulse instruments are on-going in the context of the future ESS.
Natural biological membranes are highly complex systems so simpler models are needed for structural characterization on the nanometer scale. Soft materials are also very sensitive to various stimuli and the challenge is to use dynamic external stimuli for hitherto unstudied time-dependent processes. New sample environment equipment for humidity, temperature, electric field and pressure underpins new science.
For many years neutron scattering facilities have depended on 3He for a large fraction of their detector requirements. The current and foreseeable penury in supply of 3He requires new technologies for cost effective, large area detectors. This work seeks to develop 6Li-loaded scintillation detectors and gaseous detectors using solid 10B converters as the most promising candidates.
More details (including images and videos) on these NMI3 activities can be found in the periodic reports and on the website (nmi3.eu).
Project Context and Objectives:
WP2 Dissemination and Outreach
Task 2.1 Internet portal as internal and external communication tool
Our ultimate objective was to have an internet portal as well adapted to the current and future needs of the scientific community as possible, with relevant information to the project members and outside world. The NMI3 e-newsletter keeps subscribers informed while attracting visitors to the website.
Task 2.2 Scientific and public outreach
It is essential to widely publicise the successful outcome of activities supported by the project. We thus aimed to create and disseminate material and activities to promote the scientific achievements obtained thanks to NMI3 support.
Task 2.3 Developing the Muon user community
Outreach activities to bring the unique capabilities of muon spectroscopy to the attention of the wider scientific community with the aim of attracting new users to the technique. Developing webpages and publicity material with a focus on high field muon measurements and planning workshops to promote the muon technique.
WP3 E-learning
Educating students and young scientists in the area of neutron scattering is a key for sustaining neutron research in Europe and attracting new users to the large scale facilities. As the curriculum of master courses in physics, chemistry or other related natural sciences does generally not include neutron scattering in any depth, it is essential to dispense such training via additional dedicated actions. The task of this networking initiative is to profit from modern web-based pedagogical tools and to setup an e-learning portal to promote neutron science in Europe.
Several specialized neutron courses organized by research centres and universities exist and provide a comprehensive introduction to neutron techniques often accompanied by hands on training at neutron sources. Access to these training courses is supported by NMI3 in the present project in the work package dedicated to The European Neutron and Muon School (WP4). The continuing success of this training is one of the components that maintain Europe as the leading region for neutron research around the world.
However, the number of participants is strongly limited especially for the practical courses. An open access e-learning platform will diminish this restriction. In addition e-learning is able to provide teaching in neutron research without the constraints imposed by the venue and dates of a neutron school. This is important especially for master- and PhD students starting their research and depending right from the beginning on neutrons for their investigations. Furthermore web-based courses will help to prepare students better for the neutron schools.
They will equally provide in-depth learning units to be used by lectures of graduate schools in e.g. condensed matter science. Finally they will assist undergraduate students attending lectures on neutron scattering or neutron research related courses.
In the present project period (P3) we have mainly focused on
• Preparing a comprehensive entry webpage for presentation and overview of the e-learning project
• Finalising interoperability between the stand-alone software tools which we have developed for the e-learning platform
• Finalising curriculum, course material, learning goals and paths for the modules of the online courses in the platform.
• Finalising interactive learning material utilising the software tools in the platform.
• Providing a forum for sharing experiences with and requests for the e-learning platform and courses within
• Providing a library for sharing learning material from face-to-face neutron schools and other neutron teaching/learning material
• providing best-practice for teachers in terms of user-manuals for development of online courses on the e-learning platform
WP4 NaMES
The project objectives for the period February 2015 – January 2016 were:
i) To undertake the scheduled neutron and muon schools
ii) To build further synergies with WP3 (E-learning)
WP5 Integrated User Access
Easy and open access to large scale neutron and muon facilities by national and international external scientific users is a general mission of all such public-funded scientific institutions in Europe. Peer-reviewed proposal systems are established in most facilities to organize the access of the scientific user in a structured and transparent and scientifically efficient way. Regular calls for proposals for beam time at each individual facility serve the scientific request. Unfortunately the fragmentary structure of the individual user access at the various facilities has been identified as a possible obstacle for the growing user community in Europe. In order to ask for beam time, the users have to redo similar registration procedures at each facility, to fill in similar proposal forms and to provide very similar information on legal and safety requests. Also, the facilities with large numbers of proposals (e.g. more than 600 per year at TUM) need to spend increasing amounts of time and administrative resources in organizing this task. New large facilities such as the European Spallation Source “ESS” with potential high throughput beam lines may deal with even more severe administrative efforts.
Facing these challenges, of increasing user demand and fragmented access structures, an ‘Integrated User Access (IUA)’ Networking Activity has been launched with the NMI3-II Programme in order to develop ideas for a framework to structure and harmonize an integrated access format to European national neutron and muon facilities for the scientific users. The work package consists of the following main objectives:
• Development of a generalized integrated user registration. Technical and legal requirements for a common NMI3 based single electronic user ID to access individual facility digital user office (DUO) systems will be analyzed and the best possible solution will be evaluated and established as a prototype. (Task 5.2)
• Harmonized proposal forms and templates. Forms and templates of proposal submissions at existing DUO applications will be compared and a harmonized proposal template adopted for the individual requirements will be proposed and prepared for implementation. (Task 5.3)
• Web based proposal peer review process. A framework will be developed to allow peer reviewing of submitted proposals within NMI3 web applications for small facilities, which do not operate an individual DUO. (Task 5.4)
• Platforms for cross-source independent beam time access. Platforms to submit proposals for access by the combination of instruments at the NMI3 facilities and platforms for cross-source proposals for the complementary use of instruments, laboratory services or infrastructures using different probes (e.g. neutron, muons, x-rays, facility based AFM or electron microscopy) will be considered and developed. (Task 5.5)
Work on Task 5.2 (D5.1 and D5.2) Task 5.4 (D5.5) and Task 5.5 (D5.7) were already finished and delivered in previous reporting periods. In the final reporting period work on Task 5.3 is was finished and corresponding reports delivered (D5.3 and D5.4). The work on the development of the software prototypes in Task 5.4 and 5.5 (D5.6 and D5.8) could be finished successfully and reports delivered within the time period of the project. Overall the project has successfully worked on all task and delivered planned reports and software prototypes without any severe delay. It is expected that the results of the WP will successfully help to improve and harmonize the user access and service at the neutron and muon facilities in the near future.
WP6 Data Analysis Standards
High resolution detectors and higher data rates, among others, make new demands on software that require professional software solutions. In particular, new instruments constitute a considerable challenge for software provision and failure to address this issue leads to a delay in the scientific impact of new investment.
The importance of data analysis is clear and has become a focal point of efforts to optimise scientific production. The aim of this networking activity is to determine how to develop, deploy and operate a common data analysis software infrastructure to facilitate joint software development in the neutron scattering community.
The Data Analysis Standards networking work-package began with two review tasks: review existing data analysis software and practices of software developers and review existing solutions for a common data analysis infrastructure. Based on the reports from these tasks, the key phase of the project was to develop a small number of prototype software solutions in areas chosen by the partners. The goal was to deploy functionality that exists at some facilities in the common framework thereby making it accessible to and optimised for all partners.
Task 1: Review existing data analysis software and practices of software developers
Task 2: Review existing solutions for a common data analysis infrastructure
Task 3: Develop prototype software in chosen solution for representative applications
Task 4: Evaluate prototype software
WP17 Muons
Task 17.2 Software Development for Muon Data Analysis
Work developing state of the art data reduction methods applicable to new applications of the muon technique. Specifying and coding routines to help user groups get the best from their data, and considering how simulation codes can be exploited during data analysis.
Task 17.3 Concept Studies for Future Muon Sources
Taking a forward look at the next generation muon sources, instrumentation and user requirements. Providing a concept study for a muon micro-beam and investigating requirements for future high intensity sources.
Task 17.4 Detector Technologies for Pulsed Muon Sources
Collaborative work developing Geiger-mode Avalanche Photodiode based detectors for pulsed muon beams. Developing and using a test system to evaluate detector parameters, with a particular focus on characterising device dead time.
WP18 Imaging
The efforts in JRA-Imaging in the current reporting period were focused in finalizing the project and providing of all deliverables. Experiments with external users by using of equipment which was designed and manufactured in the frame of the project were performed. The project partners used the established collaborations for building of equipment, exchange of knowhow, performing of joint experiments and discovering the capabilities of other facilities. Different platforms for simulation and data processing were developed which allow for analysis of experimental data with high precision and reliability.
WP19 Advanced Methods and Techniques
Task 19.1: Sub-mm3 samples for extreme environments
The problem of designing neutron instruments for dealing with small samples in extreme environments was addressed in two ways:
1. Developing focusing optics for a realistic experimental setup such as the IN5 or ThALES instruments at ILL, capable of capturing most of the source brightness and of converting it into a flux increase at the sample.
2. Design the instrument such as to take full advantage of the small solid angle allowed by the extreme sample environment. The conceptual design of instruments optimized for extreme conditions were carried out.
Task 19.3: Spin Echo with Oscillating Intensity for ESS
This task is devoted to developments for the application of Neutron Spin Echo (NSE) and its variant MIEZE techniques at spallation sources, especially at the ESS. The main objectives for this period were:
1. Test the performance of the resonant circuits to modulate the amplitude of the RF field as a function of time in the resonance coils, to keep the amplitude of the resonant magnetic field tuned with the wavelength of the neutrons.
2. Define new measurement strategies and new data analysis concepts to transfer the MIEZE technique from the currently reactor based instruments to a pulsed source as ESS.
Task 19.4: Choppers for the ESS instrumentation
The ESS is planned as intense long pulse neutron source with an effective neutron pulse length of the order of 2ms at a repetition frequency of 10..20Hz. With these parameters it is obvious that at least for all instruments that do not correspond to reactor instruments with velocity selectors (i.e. SANS, NSE, reflectometry) additional pulse shaping is required to achieve a reasonable resolution. This pulse shaping has to be performed by some kind of choppers. One task certainly is to modify existing chopper families (Fermi choppers, disk choppers with and without magnetic bearings) such that they meet the harsher radiation requirements of the ESS environment. The ultimate idea is to compose a Fermi chopper type by an array of slim rotators that are operated synchronously and eventually with adjustable phase shifts. To cover a larger area, a staggered array of these rotors with small diameters is needed. Here we proceed investigating the capabilities, properties and feasibility of such new chopper concepts that may allow for high frequency (KHz), large area and adaptability to focusing strategies. At the same time the kinetic energy shall be limited such that safety issues do not prevent their practical After conceptual test that proved the feasibility of phase control of a slim rotor in air up to 200Hz rotation speed and conceptual design of the rotor by initial FE-calculation now construction drawings and production procedures for a final test with neutrons are in on going preparation that will allow us also to assess the mechanical and neutronic layout of the rotor. For that purpose a construction for a single rotor running in vacuum up to 1KHz is in progress. The results will yield the reports on mechanics and neutronics of the rotor including experimental verification in order to produce substantial design reports.
Task 19.5: Polarising all neutrons in a beam
Polarized neutron beams are widely used for materials sciences investigations covering a broad range of research fields from hard-condensed matter (magnetic materials, superconductors, etc) to soft matter (polymers, proteins, etc.) and biology. Current neutron polarizers act as a spin-filters, and select only one of the two spin-states of the neutron beam (up and down) while discarding the other. Thus polarized neutron beams suffer an intensity loss of at least 50% depending on the performance of e.g. 3He filters or polarizing super-mirror-based devices.
The new design conceived in the frame of this project overcomes the existing limitations and shows that it is possible to flip one polarization (e.g. of the transmitted beam using a broad band radio-frequency flipper) and then recombine the two beams. To satisfy Liouville’s theorem, phase space volume necessarily increases in divergence, but the beam is homogeneous and thus be used for several neutron scattering applications. Numerical simulation were performed to estimate the efficiency of the device.
WP20 Soft Bio Materials
Task 20.1. A platform for model biological membranes
Natural biological membranes are highly complex systems, composed of different lipids, proteins, sterols, etc. As a result of this complexity, native membranes are difficult to study and simpler models need to be devised for structural characterization in the fraction of nanometer scale. Floating bilayer other model membranes systems generally studied suffer from a number of drawbacks and are not always suitable to mimic the complexity of real membranes. A very topical issue in this field is the development of reliable protocols for reconstitution of membrane proteins into model membranes. With these aims, different approaches will be studied to produce reproducible and realistic model membranes for biophysical and biological studies. In addition, there is a need for improved data analysis methods to extract as much information as possible from reflectivity data. A second aspect of the work will be in the development of novel modeling methodology, including molecular scale information from molecular dynamics simulations in the interpretation of NR data. Additionally, the deuteration of lipid compounds is essential for such studies but their chemical synthesis is challenging. We propose to extract natural lipids from the biomass produced from protein deuteration at the D-Lab facility in Grenoble.
Task 20.2. Kinetic/dynamic measurements in periodic external fields
Soft materials are very sensitive to various stimuli (mechanical deformation, electric or magnetic fields, UV or visible irradiation, pH, concentration or temperature variations)... Many of these external fields have been applied mostly statically, and we need now to study responses of the sample to periodic time dependent fields. We wish to extend the accessible fields, and develop kinetics and in situ measurements in neutron scattering.
Stopped Flow (SF) devices are used are used to record real time measurements (including very early stages of 100ms) on a sample after application of an external stimulus (dilution, mixture, pH or T-jump...). A first crucial step to improve both performances and spread kinetics studies with SF equipment could be overcome by improving the filling and emptying of the sample cell and adapting the cell volume and geometry to the amount of “available” samples (design of micro-cells or on the contrary, larger and thicker cell to reduce the number of repetitions). Another important development of these devices concerns a more precise control of temperature in order to follow phase transitions after T-jumps.
Investigation of the wide scale range intermediate states of structures displayed by soft materials is another major challenge for all future technical developments. A combined static LS / SANS setup would complement the standard SANS Q-range to smaller Q range (2 10-4 Å-1 ≤ Q ≤ 3 10-3 Å-1) and would allow accurate monitoring of aggregation phenomena, approach to a phase separation etc. Until now, a combination of SANS and dynamic light scattering (DLS) has been only achieved for a fixed light scattering angle, and static light scattering has never been used before in combination with SANS. We first propose to design such set-up.
External stimuli like UV irradiation can induce chemical reactions, and/or conformational and/or structural changes in soft materials. Application of oscillating electric field is one of them and is scarcely developed since electrolysis often occurs. We aim at developing electric field cell with electrodes outside the sample. Thermalization of the cell has to be provided.
So far, only few high resolution neutron scattering experiments addressed the dynamics of soft matter involving pressure. Some experiments investigated micro emulsions under pressure up to 500 bar, but in the pressure region of several kbar interesting questions can be addressed: proteins, for example, undergo a transition from the folded to the unfolded state not only by an increase of temperature but also at high pressure (about 7 kbar ) as shown by SANS measurements. NSE spectroscopy has a great potential in the study of internal dynamics of unfolded proteins, but its large beam cross section and its requirements of non-magnetic materials are challenging for high pressure devices. We propose to develop a non-magnetic pressure cell accepting a large incoming beam cross section and large exit angles.
Task 20.3. Humidity chamber
In-situ control of the hydration level of soft materials samples plays a crucial role in the investigations of the proton motion in Nafion membranes, the dynamics of phospholipid membranes, the structure and dynamics of clays, as well as in the study of the function/structure relationship of proteins. In the last years, ILL and HZB have been developing humidity chambers for neutron scattering using different techniques to control both relative humidity and temperature. Further developments are needed to obtain first a faster and better controlled response in wider temperature and humidity ranges.
Task 20.4. Cryogen-free cryostat with sample changer
In order to decrease dead times related to temperature and sample changes during neutron scattering experiments in cryostats, it is necessary to design and build a cryostat that features a carousel of samples either placed at room temperature or thermalized at low temperature (for example at 80K by using a cold gas stream), equipped with an automatic sample changer, and capable to extend the available temperature range (down to 3K or lower and up well above room temperature). A more compact design with less cold mass would allow rapid cool-down and sample changes by means of a robot. We propose to design and draw a new cryostat with a sample changer fulfilling these specifications.
WP21 Detectors
Work package 21 is divided into two tasks, each of which seeks to develop a non-3He based detector technology for neutron scattering applications. Task 21.1 examines aspects of scintillation detector technology, while task 21.2 is concerned with the development of gas detectors based on solid 10B converter. Within this period the objectives are to complete the following subtasks:
Task 21.1.5 Detector evaluation and final report
Task 21.2.4 Concept study for large area detectors
Task 21.1.5 builds on the work done in previous subtasks whereby ISIS and Jülich developed scintillation detectors based on ZnS:Ag/6LiF read out with wavelength shifting (WLS) fibres and vacuum photomultiplier tubes (PMTs). This task also continues the work by CNR/Perugia on the development of SiPMs coupled to GS20 glass scintillator. The output of this task is a report, deliverable D21.9 which details the status of the scintillation detector development carried out in this work package.
The output of task 21.4 are two reports, D21.14 and D21.15 which detail the concept studies carried out for large area detectors based on gas detectors with solid 10B convertor. D21.14 is the concept study of a large area detector based on MWPC, while D21.15 is the concept study of a large area detector based on Micromegas.
Project Results:
WP1 – Management
Within the last 48 months the project manager took care of the follow-up of delivery status of the different WP obligations. The project manager keeps track of all issues which may arise and need to be discussed in the Board meetings. She also stays in continuous contact with the project officer.
The project manager composed all necessary documents necessary for the periodic & final reports and the two amendments. This included the financial reports and money transfers to beneficiaries.
She planned and organized the annual General Assemblies with adjacent Board meetings as well as the Advisory Committee sessions and the review of the School reports (NaMES in WP4). The set-up of the respective agendas and discussion points is in the remits of the project manager, who also proposes and invites the external speakers to the resp. event:
In addition to the very efficient and lean project management, the project manager took care of the industry related activities added in WP1 in the negotiation phase. Three major workshops have been held. The first on ‘Industry as a supplier’ held at the ICNS in Edinburgh, 2013. The second strand was ‘industry as a user’ for which an ‘Industry Advisory Board’ has been set-up. This Board includes industrial representatives using both neutrons and synchrotron facilities. The following two workshops have been done jointly with the homologue lightsoures project CALIPSO. More information is available on http://nmi3.eu/about-nmi3/industry-.html .
NETWORKING ACTVITIES
WP2 – Dissemination and Outreach
Communication is essential for raising awareness of research conducted in Europe’s neutron scattering and muon spectroscopy facilities. One of the goals of NMI3-II was to produce articles and videos that could make its scientific activities and achievements more tangible to non-expert publics.
The website nmi3.eu was an important communication channel among project participants and provides a window to the outside world. Over the years it became a reference to many seeking information about specific neutron techniques.
The website Neutronsources.org which is an initiative of NMI3, was launched to provide information and news on research using neutron beams to a worldwide audience. It is supported by a network of European press officers and thus contains material sent by all neutron sources around the world. There is a page dedicated to each neutron centre and association, news about scientific achievements and events. Those who are new to the field can browse the “Science with Neutrons” page to get to know more about neutrons, their characteristics and applications. Under “Resources” one can learn about projects as well as useful software and tables. On the calendar, you can browse future and past neutron events such as conferences, workshops and schools. Have you got an idea for a neutron experiment? The website tells you the facilities’ deadlines for submission of proposals as well as the operating periods. Are you looking for a job? You might find it on the job tab. The website will remain active after the end of the project.
Collaboration among press officers of large scale facilities is important to go farther in the promotion and dissemination of the science produced in each of the large scale facilities. Efforts were made within NMI3-II to foster these collaborations by organising regular meetings. The workshop “Public Awareness of Research Infrastructures” in June 2015, which was co-organised by the NMI3 Information Manager, was an interesting opportunity to present expectations, experiences and give examples of work on public relations in each facility.
Would you like to know how neutron scattering contributes to advancing science and technology? The European Neutron Scattering Association published a new brochure on Neutrons for science and technology. It highlights typical work of the academic and industrial user communities to illustrate the scope and potential of neutrons. NMI3-II coordinated the publication. The aim is to distribute copies mainly to scientists and students from other fields, in order to attract new users to the technique.
The development of the muon community focussed on themed workshops on functional materials and soft matter, while publicity leaflets and the muonsources.org website have been created with a view to introducing new user groups to muon technique.
WP3 - E-learning, description of the main S & T results
Introduction
Since experimental neutron scattering is mostly restricted to large-scale facilities, not all students have access to learning the technique at their home institution. Providing a freely accessible e-learning portal for neutron scattering is therefore an important outreach task in order to secure and educate the future users and scientists at neutron scattering facilities. This task and challenge has been taken up by the WP3 partners. The collaboration included people from a broad range of disciplines, from didactics and teaching in physics, through neutron scattering in theory, simulation and experiment to programming and web-design. The aim is to offer online teaching material to university students and their teachers as well as scientists from other fields wanting to learn about neutron scattering techniques.
The Platform
To address this teaching challenge, the WP3 partners have developed and utilized an e-learning portal for neutron scattering under the working title “Virtual Neutrons for Teaching” (VNT) – now fully developed with frontpage available at http://www.e-neutrons.org. - See Figure 1 (left).
Figure 1:Left: Frontpage from e-neutrons.org. Right: The tools of interaction between the teacher, student and material in the WP3 e-learning project.
Any learning situation can be schematically described in general terms by the interactions between three parts (topic, teacher and student) in the so-called didactic triangle. In a pure e-learning situation the means of interaction are not the same as in a face-to-face class-room situation; some tools are missing while others are gained. The challenge in any learning situation is to balance the interactions on the sides of the triangle in order to optimise the outcome for every student. During the course of the project, key technical and didactical choices have influenced the platform developments. In Figure 1 (right), we have shown schematically some of the neutron e-learning tools we have developed for the platform and how they fit into the didactic triangle.
Once a user is registered at e-neutrons.org access is granted to the full e-learning platform, made up from three main parts:
A “WIKIbook” provided by Mediawiki with various extensions, e.g. for producing mathematical expressions, playing the role of textbook-material – See Figure 2 (left)
A Learning Management System (LMS) provided by the Moodle system, providing exercises, quizzes and evaluation – See Figure 2 (right)
A web simulator for the McStas neutron instrument simulation program, allowing to perform virtual neutron scattering experiments – See Figure 3
Figure 2 – Left: Textbook example from the WIKIbook - Right: Course material example from the LMS
Figure 3 – Left: Configuration page for a virtual SANS instrument - Right: Simulation output from the same virtual instrument
Learning material
We have designed and implemented 10 neutron scattering modules whereof 8 are general introduction to neutron scattering and techniques and 2 are specialised applications in imaging and magnetic neutron scattering. Two courses are constructed from these modules, basically with the same content, but they differ in learning path restrictions and guidance as one course is intended for student self-study. Whereas, the material in the other can be taken in any order and modules skipped, to fit a course in a blended learning setting.
Using the online simulator that contains virtual instruments with samples, the student can tune pre-defined parameters to obtain synthetic data from Monte-Carlo simulations. The resulting data can be analysed like real, measured data. In quiz-lessons connected with some of the instruments the students can explore through theory and virtual experiments, how a neutron scattering technique is used to solve a scientific problem. These quiz-lessons are constructed with the advanced Moodle quiz module which has been used to implement many types of quizzes ranging from student self-tests which can take some minutes up to an hour or two for students to complete, to stand-alone learning modules which take several hours to complete.
Background reading material is made available through the WIKIbook and contains written material and exercises adapted and reworked from coherent and progressive lecture notes collected in an (otherwise unpublished) book by several authors, but with main author and moderator Kim Lefmann.
The tools in the e-learning platform have been thoroughly tested as they were developed in blended learning settings i.e. class-room courses with supplementary material in the e-learning platform. A total number of about 150 students have participated in the tests, mainly in face-to-face courses held in Denmark, Germany and Sweden. User comments in e.g. quiz-replies and focus group interviews have been used to iterate the contents of each module of the courses as well optimise the learning material and activities.
Interoperability of the different software used in the e-learning platform has been ensured through an LDAP based tool developed within this project which from the entry page http://www.e-neutrons.org handles the user account creation and login to each of the three software programmes with the same credentials.
The neutron community are invited to contribute material from schools, pedagogical review papers on methods and techniques, books on neutron scattering which are no longer in print, handbooks and multimedia material via the Library, which is currently implemented as part of the Moodle LMS and upload rights will be granted on request. We have uploaded some key examples as part of WP3. The provision of established books, however, is limited by copyright restrictions. Open source material from schools organised in NaMES (see WP4) and international schools will we added as they become available.
WP4
The achievement is the creation of a distributed Training facility called NaMES - Neutron and Muon European Schools. Collective announcement of a series of schools (brochure and website) ensures their successful occurrence and the refinement of overall interaction and organisation of the schools in the series. Over the four years 17 schools have received support for travel and subsistence cost of the students by NMI3-II. Roughly 1500 students have been supported via the project and hence been made aware of NMI3-II.
The School directors had to provide a detailed financial report in order to make sure that the support is dedicated only to travel and subsistence for students and in special cases for lecturers (in Eastern European countries). All school have put in place a satisfaction survey. The exploitation and hence improvement measures to be taken are in the remits of the respective school organiser.
The NMI3-II Advisory Committee (AC) conducted the first evaluation of the schools in the beginning of 2013. According to this evaluation the schools were judged to be broadly successful. However, in order to attain high, shared standards, recommendations for improving future evaluations of schools have been made. The School reporting rules were refined (WP1) in order to assure a sound assessment of the financial support compared to the total cost of the schools.
The first NaMES schools directors’ Synergy Workshop was in Berlin (June 2013), the second NaMES meeting (September 2014) was held in Zaragoza - both satellites to the NMI3 General Assembly. These meetings brought together all schools’ directors, some AC members and the NMI3 management. They provided an invaluable forum of discussion for school organization within the NaMES umbrella.
Synergies with the E-learning work package (WP3) have been identified and materials provided.
WP5
Easy and open access to large scale neutron and muon facilities by national and international external scientific users is a general mission of all such public-funded scientific institutions in Europe. Unfortunately the fragmentary structure of the individual user access at the various facilities has been identified as a possible obstacle for the growing user community in Europe. Also, the facilities with large numbers of proposals (e.g. more than 600 per year at TUM) need to spend increasing amounts of time and administrative resources in organizing this task. New large facilities such as the European Spallation Source “ESS” with potential high throughput beam lines may deal with even more severe administrative efforts.
Facing these challenges, of increasing user demand and fragmented access structures, the following objectives have been successfully achieved. The eleven partner facilities offering open access to users, did work in mutual agreement on the tasks defined according to the five objectives, each task being led by one partner.
Development of a generalized integrated user registration. Technical and legal requirements for a common NMI3 based single electronic user ID to access individual facility digital user office (DUO) systems will be analyzed and the best possible solution will be evaluated and established as a prototype. (Task 5.2)
Harmonized proposal forms and templates. Forms and templates of proposal submissions at existing DUO applications will be compared and a harmonized proposal template adopted for the individual requirements will be proposed and prepared for implementation. (Task 5.3)
Web based proposal peer review process. A framework will be developed to allow peer reviewing of submitted proposals within NMI3 web applications for small facilities, which do not operate an individual DUO. (Task 5.4)
Platforms for cross-source independent beam time access. Platforms to submit proposals for access by the combination of instruments at the NMI3 facilities and platforms for cross-source proposals for the complementary use of instruments, laboratory services or infrastructures using different probes (e.g. neutron, muons, x-rays, facility based AFM or electron microscopy) will be considered and developed. (Task 5.5)
WP6
A clear overview on the existing software landscape for neutron/muon scattering has been established as most of the available neutron and muon software has been identified and evaluated. These have been gathered in a Live DVD, which facilitates software use and testing. The practices employed to develop and maintain the software have been analysed to define a set of recommendations to be used in further projects. The criteria used for the software review are deployment, installation, usability, functionality, maintenance and extendibility. The criteria used for the software practices are related to version control, points of failure, testing, documentation and code duplication.
Among currently developed software, special focus has been given to the Mantid project, which has been developed recently for spallation source instruments at ISIS and SNS. It is investigated to what extent this framework can be used for instruments based at continuous neutron sources. To evaluate the effort required to deliver such functionality, new data loaders have been successfully written for the time-of-flight spectrometers IN4, IN5, IN6 at ILL, MiBemol at LLB, and Focus at SINQ/PSI. A set of existing data treatment algorithms, already available in Mantid, was used, and results were compared satisfactorily with those e.g. of the LAMP software.
A loader for the D33 SANS instrument at ILL was also written. The McStas software was upgraded to write NeXus files readable by Mantid, to account for any virtual instrument model geometry. However, implementing loaders for scanning instruments tends to be more complex in the current Mantid framework. The team will continue investigating beyond the project. Even though the Mantid software provides extensive functionality, some complex and very specific new features may have to be developed as separate, specialized software components.
All deliverables have been published on the NMI3-II web site http://nmi3.eu/about-nmi3/networking/data-analysis-standards.html and are available to the public, including the produced source code.
JOINT RESEARCH ACTIVITIES
WP17 - Muons
Software Development for Muon Data Analysis
Early in the project we looked at common data analysis procedures, highlighting a requirement for new data analysis tools for processing Avoided Level Crossing spectra, and for carrying out phase-quadrature and rotating reference frame transforms (Fig. 1). These codes were released under the Mantid framework and are now in regular use by the user community.
A parallel study considered how simulation codes might be exploited during data analysis. The ‘Quantum’ package for the simulation of muon spin evolution using the density matrix method was refactored as Python subroutines for execution within the Mantid framework. A number of case studies were developed to illustrate the scope and flexibility of the code (Fig. 1). The potential for using ab initio Density Functional Theory methods as an aid to interpreting Avoided Level Crossing spectra was also investigated. Molecular couplings for an example muoniated system were calculated, and used to explore methods for refining these values obtained from simulation. The work demonstrated that further development was required before the technique can be reliably used as a predictive tool in experiments.
Figure 1: Workflow for analysis of Avoided Level Crossing data (left), a Rotating Reference Frame transformation of muon spin rotation data (centre) and data modelling carried out using the ‘Quantum’ package.
Concept Studies for Future Muon Sources
Early discussions with Prof Bob Cywinski, a member of the University of Huddersfield’s International Institute for Accelerator Applications, led to an extended study of target technologies for muon production. The collaboration developed, with Prof Cywinski hosting at a workshop January 2015 (Fig. 2), which brought together facility staff, accelerator scientists and facility users to consider the requirements for next generation muon sources and the scientific problems they might address.
A concept study to investigate the feasibility and research potential of a muon micro-beam (Fig. 2) was also developed as part of the project. The work considered the possibility of carrying out µSR experiments on ~100µm samples, the potential for scanning the sample to investigate inhomogeneities and the possibility of completing parallel measurement of several micro-samples. Very promising results were obtained, with results suggesting a facility could develop a practical micro-beam with relatively modest resources, with greater intensities being possible in the future using more sophisticated focussing and slit systems (akin to electron microscopy).
Figure 2: Attendees at the Future Muon Sources workshop (left) held and the University of Huddersfield, and beam transport modelling for a study investigating the feasibility of producing a muon micro-beam.
Detector Technologies for Pulsed Muon Sources
Avalanche Photodiodes (APDs) had previously been shown to provide excellent timing resolution that was invariant with magnetic fields. However, their ability to measure the very high instantaneous rates inherent to use at a pulsed muon source was not established. Work within this project developed a systematic study of the performance and operating parameters of APD-based detectors (Fig. 3), enabling the dead time to be properly characterised and compared to equivalent PMT-based systems.
Tests quickly established that the baseline performance of APDs at very high data rates was not ideal because of their extended recovery/dead time (Fig. 3). However, increasing the pixelation greatly improved performance, and further gains were realised by differentiating device output signals before acquisition. For an optimised system, a performance comparable to a photomultiplier-based detector has been realised; however, further work is needed to demonstrate their suitability for building the high density arrays presently being planned for the MuSR and HiFi instruments at ISIS. A fruitful collaboration is developing between the muon groups at the ISIS and J-PARC pulsed sources, with useful discussions ongoing as to how to make best use of these devices in this environment.
Figure 3: APD test devices assembled within a light-tight enclosure (left) and signals measured for SensL APDs, comparing the response of the slow (centre) and fast/differentiated outputs. The extended recovery, particularly for the slow output, is immediately apparent.
WP18 – Neutron imaging
Nano- and micro structures resolved dark-field neutron imaging with grating interferometers (nGI) New set of gratings was manufactured at PSI and TUM (1a). The new gratings allow for increased visibility contrast and therefore for improved performance of the nGI-setup (1b,c). A compact water-cooled 0.4 T electromagnet (1d) was constructed at PSI in cooperation with TUM. To minimize the influence of the magnetic field on the grating setup, the magnet is strongly shielded. A modification of the field distribution inside the magnet is possible by an asymmetric operation of the coils which changes the homogeneous field inside into a distorted configuration. A new nGI setup at ANTARES imaging beamline at FRM-II was constructed with a possibility to rotate all gratings simultaneously around the neutron beam (1b,c). Hence, by an evaluation of the dark-field contrast variation as a function of the rotation angle of the gratings, it is possible to detect anisotropy directions within the microstructure of a sample (1e).
a b c d e
Figure 1. a) new gratings manufactured at TUM; b)c) photos of the new nGI setup at the ANTARES instrument (FRM-II); d) new magnet constructed at PSI; e) anisotropy in the microstructural properties of the materials (bottom - Gd µm-grating , middle - copper rod, right - fiberglass material) measured by nGI.
Direct high resolution neutron imaging
The high-resolution neutron imaging test arrangement is currently being developed at NIAG, PSI in collaboration with HZB under the project entitled “Neutron microscope” (2a). The goal of the project is to develop and implement a dedicated optical system that would allow neutron imaging experiments with spatial resolution below 5 micrometres and within reasonable exposure times. The key element is the development of new high-resolution scintillator screens. Two distinct ways are being followed up– (i) very thin diffuse scintillator based on Gd substances (e.g. Gd2O2S:Tb3+) and (ii) micro-structured scintillator screens based on Gd substances (2b). A magnifying optical system was developed. The optical design of the lens has been performed and the first tests were carried out (2c,d). A prototype of new high resolution neutron detector system (2a) at V7/CONRAD-2 instrument at HZB made possible to reach spatial resolution of 15 µm in radiographic images. The optimized detector system opened the possibility of performing tomography experiments (2e) where several hundreds of sample projections are recorded .
a b c d e
Figure 2. a) high-resolution detector at HZB; b) diffusive (top) and micro-structured (bottom) scintillators; c) high-resolution detector setup at PSI; d) high-resolution neutron image with pixel size 1.5 µm; e) high resolution neutron tomography of hydrogen embrittlement in iron (red=hydrogen).
Energy-selective neutron imaging
A new energy-selective setup (3a,b) was designed and installed at the neutron imaging instrument CONRAD2 at HZB. The obtained wavelength resolution is in the range of 3 %. The wavelength of the output monochromatic beam can be tuned continuously in the range of 1.5 Å – 6 Å. The setup was used for nondestructive 3D mapping of crystallographic phases within the bulk (centimeter range) of samples with micrometer-scale resolution (3c). The Bragg-edge mapping using continuous neutron sources was extended to Time-of-Flight (ToF) technique on pulsed sources (3d).
a b c d
Figure 3. a) double-crystal monochromator installed at the CONRAD-2 instrument at HZB; b) photo of the device; c) Bragg-edge mapping of TRIP steel – 3D crystallographic phase separation; d) Bragg-edge analysis of crystallographic phases in steel by using double crystal monocromator (top) and ToF method (bottom).
SANS 3D: vectorial magnetic imaging of nano-objects
Polarized SANS measurements have been performed on various systems such as: (i) carpets of Co nanowires deposited on a sapphire substrate (4a), (ii) regular arras of magnetic nanowires deposited in alumina membranes, (iii) aggregates of Co nanowires synthesized by the polyol process (4b). For these different systems Nmag software tool was used to perform micromagnetic simulations (4c,d).
a b c d
Figure 4. a) Carpet of Co nanowires with the SANS scattering signal; b) aggregates of nanowires with the SANS scattering signal; c,d) Modeling of these systems using micromagnetic simuations of large arrays of nanowires.
Precession techniques for imaging magnetic structures in thin film systems
Very narrow beams in were produced by using either a silicon reflector (5a) or a neutron wave-guide so that a neutron beam can be scanned across the magnetic wire (5b). Simulations help for data analysis (5c).
a b c
Figure 5. a) Micro-beam (20 µm) produced by using a reflection system; b) Neutron precession measurement through a magnetic micro-wire; c) Simulation of a precession measurement through a magnetic microwire.
WP19 Advanced Methods and Techniques
Sub-mm3 samples for extreme environments
The focusing optics for the upgraded ILL IN5 instrument has been optimized via numerical simulations (McStas) and a particle swarm optimization algorithm appropriate for noisy problems (iFit library). The results confirm that a multi-channel guide is not necessary (Fig. 19.1). For the ThALES 10T magnet entrance channel a focusing guide element has been optimized by a Monte Carlo method (SimRes). The best guide for optimizing the flux at the sample position turned out to be a linear tapered shape.
Figure 19.1: Right: vertical profile of the best three-channel guide found for IN5. Middle: performance of a focusing guide element of the ThALES 10T magnet. Right: schematic view of the multipurpose instrument devised for extreme conditions-
The conceptual design of three extreme condition instruments has been achieved. A) A multi-purpose instrument (Helmholtz-Zentrum Berlin) which operates in three modes: diffraction, spectroscopy, and SANS. Such multi-functionality is achieved by a proper design, which consists of a bi-spectral moderator, for cold and thermal neutrons, with a specially designed extraction system; a transport system that incorporates a chopper cascade; etc. Numerical simulations (VITESS) show that its performance and compares favourably with that of existing instruments. B) XtremeD, optimized for high pressure and/or high magnetic field. C) EXPRESSO, a neutron diffractometer optimized for high pressures and the long pulse characteristic of the ESS, will deliver high fluxes at both long and short wavelengths.The design allows direct access to the sample position, and the incorporation of optical probes for in situ pressure measurement (by ruby fluorescence) and ancillary Raman spectroscopy. This set-up also enables a laser heating arrangement of the type used at many synchrotron beam lines.
Spin Echo with Oscillating Intensity for ESS
This joint-research-project is devoted to adaption of the MIEZE technique running on reactor-based instruments like MIRA und RESEDA at the FRM II to the needs of pulsed beams. New resonant spin flipper coils to achieve higher frequencies (resonant spin flip at f = 3.45 MHz) and therefore a higher resolution have been tested (Fig. 19.2). Problems with high currents have been addressed.
Figure 19.2 Left: the resonance circuit used for NRSE and MIEZE. Middle: (a) conventional coil design used in transversal and longitudinal NRSE; (b) simple coil with low inductivity used for tests. Right: scan of static field B2 at fixed current through resonant flipper coil.
The CASCADE system detector was evaluated, modified and tested for accepting a chopper signal from either a chopper or a synchronization pulse from a pulsed neutron source. Tests were performed at the reactor instruments MIRA and RESEDA of FRM II and at the pulsed beam line CG-1D at HFIR, Oak Ridge National Laboratory (ORNL). The design for the data acquisition and the fitting procedure tested in the pulsed beam line can be clearly chosen as the standard measurement strategy for the planned longitudinal MIEZE spectrometer at ESS. A test of a spin-echo modulated small angle scattering has been successfully performed in the Larmor instrument of ISIS, confirming that there are no significant difficulties in synchronising data collection to the ISIS pulse and no unexpected additional problems.
Choppers for the ESS instrumentation
A chopper concept has been studied with a small high speed motor connected to the rotor by means of an elastic shaft. The system stability at high rotation frequency has been analysed by finite element calculations. The neutronic properties of a single chopper and of a chopper array have been analyzed by means of computations. A (scalable) chopper array with 1% overlapping has been devised which provides the appropriate neutron suppression. Undesirable effects as the suppression of slow neutrons at high rotation frequency have been studied and solutions proposed.
Figure 19.3: Left: picture of the system with labels for the components; Center: test stand for mechanical rotor assessment and the drive electronics rack; Right: results of the stability analysis at high rotation speed.
Polarising all neutrons in a beam
The configuration (Fig. 19.5) is a combination of a neutron polarizing and a neutron transport system, in which both neutron spin states (├ ├|↑┤⟩ or ├ ├|↓┤⟩) can be separated, manipulated and re-combined to a beam that can be used for polarized neutron scattering experiments. A super-mirror polarizing cavity comprising two super-mirrors arranged separates the incoming neutron beam into three beams. The lateral beams have polarizations opposite to the central beam. A broadband spin flipper flips the spin state of the neutrons in the central beam. Then the three neutron beams are recombined at the central position of a neutron scattering instrument. Monte Carlo simulations (VITESS) show that the setup has high performance over a broad range of the relevant parameters.
Figure 19.4: Left and center: schematic view of the device. Right: normalised neutron intensity (a), polarisation (b), horizontal beam profile (c) and divergence (d) of the system for three values of the angle θ for the polarising cavity.
WP˗ 20 Advanced Neutron tools for Soft and Biomaterials
A Platform for model biological membranes
After extraction, purification and analysis of natural lipids from the biomass produced from protein deuteration at the D-Lab facility at ILL, a few neutron reflectivity studies of biomolecules at the surface of natural or deuterated lipids membranes have been then performed. Besides, the method for creating unconstrained, deposited biomembranes on the top of a chemisorbed Self Assembled Monolayer (SAM) of phospholipids on a substrate producing reliable SAM’s of effectively 100% coverage is now regularly used as a sample-environment option for user experiments. Significant progresses have been made in the incorporation of Molecular Dynamics calculations for the interpretation of neutron reflectivity curves. Complex membranes from lipids mixed with proteins or peptides, natural ore deuterated, can be better studied by neutron reflectometry thanks to these novel tools, labelled biomaterials and methods.
Kinetic/dynamic measurements in periodic external fields
A new design of observation head for stopped-flow (SF) device has been achieved, allowing a reduction (40%) of the sample volume, and the use of Hellma© cells of different neutron paths. Improvement of the quality of mixing thanks to a new damping grid combined to an automatic push and pumping system (tested) would decrease the duration of mixing and allow measurements of first steps of kinetics after mixing. The SF device, shown in Figure 1, now provides the ability to control the temperature inside the head independently from the temperature of the bath before mixing liquids, and isolates the cell from environmental temperature variations.
A multi-angle dynamic light scattering setup is definitely installed on the Small Angle Neutron Scattering (SANS) spectrometer KWS2 at JCNS. It can be combined with an external commercial static light scattering instrument.
Figure 1.Photograph of the new thermalized observation head mounted on the stopped-flow system at ILL.
Design and photograph of a thin walled TiZr pressure cell suitable for high scattering angles optimized for NSE experiments, tested up to 460 MPa for an operation pressure up to 400 MPa. Design of a thermalized electric field cell prototype with electrodes outside the sample in a quartz cell.
Various prototypes of pressure devices for SANS and Neuron Spin Echo (NSE) have been tested and developed during the project. A thin walled TiZr pressure cell dedicated to NSE experiments will allow reaching 400 MPa (see Figure 1) on large sample area (3*3 cm2). A TiAl6V4 alloy has been validated as a good material for high performance pressure cell windows (up to 700 MPa in SANS). Design of a separation chamber between the pressure fluid and the sample has been validated up to 700MPa. From experience gained on one prototype with sapphire windows tested up to 450 MPa and validated up to 330 MPa, three versions of pressure cells with sapphire win dows are foreseen: one for NSE experiments up to 50 MPa for 30mm diameter sample’s area and two for SANS experiments, up to 500 MPa (with a compromise with respect to the available opening angle or a beam size (intensity) reduction) and up to 300 MPa (without compromise).
Simulations using Finite Element Methods software, COMSOL® Multiphysics, of electric field and air flow have been performed at LLB in order to build a thermalized electric field (EF) cell with electrodes out of the sample cuvette (see Figure 1). The cell body and the sample chamber of a second prototype of EF cell built during the project are made from PLA by 3D printing. On assembly, the cell was tested successfully with various usual solvents; measurements and simulations of electric field have been compared. Feasibility of thermalization by a simple stream of temperate air flow has been demonstrated.
Humidity chamber
Considerable and collaborative efforts at HZB and ILL have focussed on the design of a humidity cell with a factor of 5 improvements in humidity (i.e. temperature) stabilization. After series of tests on a first prototype chamber in 2014, a second improved version was produced in 2015 (see Figure 2). Highest precision in humidity control is achieved from 0% to 99% relative humidity (r.H.) on both prototypes; special options using Peltier elements (see Figure23) and temperature regulation for fast sample equilibration are required to reach 100% r.H. saturation. The prototype BerILL 1.0 is in HZB user-office since October 2015.
Figure 2. Humidity chamber BerILL 1.0 at HZB and BerILL 2.0 at ILL Grenoble. Base design of the sample stage with mini goniometer for sample alignment. Peltier to control sample holder T° for highest humidity applications.
Cryogen free cryostat
A compact and modular cryogen-free cryostat was built with a separate sample space isolation vacuum and a cold head isolation vacuum, allowing the cold volume to be minimized (see Figure 3). Thermal coupling to the cold head is achieved by heat switches to realize fast cool down and warm up. Some elements have been modified after temperature tests. A standardized sample holder providing a pin connection for thermal link and thermometry facilitates sample change and interchange. The sample storage and a robot for sample handling are foreseen to be located at room temperature.
Figure 3. Cryogen-free cryostat: drawings and picture.
WP21 – Detectors
Scintillation detectors
For the scintillation detectors ISIS and Jülich have each developed detectors using ZnS:Ag/6LiF scintillator. The detectors use wavelength shifting (WLS) fibres and multi anode photomultiplier tubes MaPMTs. Different fibre coding, electronics and signal processing have been developed. The final ISIS and Jülich demonstration detectors, shown in Figure 1, have been evaluated. Neutron detection efficiencies and position resolutions can easily be adapted to meet a wide range of applications. The demonstration detectors developed are modular, easy to construct and provide a means of covering large areas in a cost effective manner.
Figure 1. LHS and LC: ISIS WLS fibre demonstration detector. RC and RHS: Jülich WLS fibre demonstration detector.
CNR/Perugia has explored the potential of SiPMs for reading out large area neutron scintillation detectors. A system has been developed using up to 7.5 x 7.5 mm2 GS20 glass scintillators coupled via Plexiglass light guides to a 3 x 3mm2 SiPMs, see Figure 2. Scalable electronics has been designed and produced and a pulse shape analysis routine has been developed to identify neutron pulses.
Figure 2. LHS: Test detector with SiPM connected to GS20 glass scintillator with straight light guides. LC: Pulse height spectrum from a SiPM connected with straight light guide. RC: Four 3 x 3 mm2 SiPMs mounted on stackable electronics. RHS: Four tapered Plexiglass light guides coupling GS 20 glass scintillator to four SiPMs
Gas detectors
One of the major challenges in developing gas detectors based on solid 10Boron is the need to deposit 10Boron based layers of ~ 1 µm thickness over large areas. To assess coating quality, TUM and BNC evaluated the performance of 10B4C coatings from a number of different manufacturers produced by both magnetron sputtering and electron beam evaporation, see Figure 3. TUM developed a test detector specifically for this task. Magnetron sputtering is now the accepted standard method of producing 10B4C layers. HZB have studied alternative and potentially faster processes for depositing 10Boron based coatings. They have identified powder spray deposition with a high temperature atmospheric plasma torch as the most promising alternative technique. An experimental system has been developed as shown in Figure 3. A 2D-position sensitive detector has been developed by HZB and BNC to evaluate the quality of these coatings, which is also shown in Figure 3.
Figure 3. LHS: Examples of some of the 10Boron coatings evaluated. LC: The Microwave Atmospheric Plasma System at HZB. RC: The plasma jet after 10Boron powder injection. RHS: The 2D detector constructed by BNC and HZB.
TUM have investigated the “grooved” converters, see Figure 5, in order to reduce the number of 10B4C layers required in a detector, whilst maintaining high neutron detection efficiency. Results show that an increase in detection efficiency of up to ~50% is possible with this design. TUM have developed a concept for a large area gas detector based on these “grooved” converters and multiwire proportional chambers, MWPCs. The concept detector, shown in Figure 4, has an active area of 40 x 40 cm2 and consists of two MWPCs and four grooved converters. This concept will be developed further by the ESS.
Figure 4. LHS: Schematic cross section of a “grooved” converter. C: The large area gas detector concept based on “grooved” converters and multiwire proportional counters. RHS: photograph of the concept detector based on a micromegas amplification structure.
CEA have developed a concept for a large area gas detector based on thin meshes coated with 10B4C on both sides and a bulk micromegas amplification stage. The concept has been extensively simulated to optimise critical construction parameters, operating conditions and neutron detection efficiency. A detector with an active area of 54 x 54 mm2, shown in Figure 4, has been designed and built to test out this concept.
Potential Impact:
WP1 – Management
NMI3 as a whole can be expected to have a significant socio-economic impact. Neutron scattering and muon spectroscopy are key experimental techniques in the design and characterisation of new materials and processes. Up to two-thirds of neutron and muon experiments can be considered as being directly or indirectly related to materials and processes with potential applications, while in some facilities, close to 20% of beam-time is funded directly or indirectly (via research groups) by industry. Dissemination, outreach and education (WP2 & 3) are therefore indispensable activities with respect to future socio-economic impact. Harmonising access procedures for facilities and improving access to scientific results through improved software (WP5 & 6) will encourage new neutron and muon users, including industry with its specific requirements in terms of timely production of relevant scientific results.
More specifically, of the JRA’s, WP18 is developing neutron imaging techniques, benefitting from the unique properties of the neutron, which are analogous to well-known X-ray and microscopy techniques, and should therefore have significant impact. Similarly, WP20, focussing on soft and bio materials, will develop tools that will significantly enhance research capability, ultimately contributing to societal challenges in the health domain. Finally, the detector technology developments in WP21 could potentially be transferred to a number of companies manufacturing radiation detectors.
WP2 – Dissemination and Outreach
Communication is essential for raising awareness of research conducted in Europe’s neutron scattering and muon spectroscopy facilities. One of the goals of NMI3-II was to produce articles and videos that could make its scientific activities and achievements more tangible to non-expert publics.
The NMI3 website remained very important for the whole duration of the project as it offers useful tools to all project members. Everyone part of the scientific community, general public and policymakers can learn about the project achievements, partner facilities and other relevant information. The dissemination of the project’s scientific achievements contributes to raise awareness about the importance of neutron and muon research among diverse audiences. We publicised the scientific possibilities of these techniques in order to increase the number of users. We have in fact observed a growing number of subscriptions to our website and newsletter, and have received positive feedback from scientists worldwide e.g. via online social media (e.g. LinkedIn and Twitter). Furthermore we have come to notice that a number of external websites like e.g. Phys.org Horizon, have published news items about the project’s activities and results.
Regarding the independent website Neutronsources.org it is our objective to turn it into a sustainable reference website for the neutron community worldwide. A steadily growing number of institutions contributing to its content, indicates that we are on the good way to reach our goal. The development of the muon community has focussed on themed workshops on functional materials and soft matter, while publicity leaflets and the muonsources.org/ website have been created with a view to introducing new user groups to muon technique.
Collaboration among press officers of Europe’s neutron and muon facilities is important to go further in the promotion and dissemination of the science produced in each of the facilities and within the project. The NMI3 Information Manager thus coordinated meetings as well as an international workshop with press officers in order to foster collaboration and to achieve a sustainable communication network. Given the success of these events, future meetings are already being planned.
WP3 – E-learning
The online distribution of e-learning material on neutron scattering through http://www.e-neutrons.org and the development of a full introductory neutron scattering course which is freely available will make an important contribution to expand the neutron user community due to several factors: Students and researchers at universities without connection to local neutron scattering courses and/or without funding to travel to the limited-seat hands-on courses can by their own choice and on demand, comfortably complete a full 8-week undergraduate training programme, or briefly familiarise themselves with a particular technique in order to assess whether it will be useful for their research projects. Both factors will ease the entry into the neutron scattering community, and online availability will increase visibility world-wide, also at smaller universities. Furthermore the innovative use of virtual experiments for training, which is openly available and easily accessible through a browser, can be utilised also for existing face-to-face neutron schools (as part of blended learning), thus helping students connect theory with experiment and maximising the outcome of the limited hands-on training which is available at the neutron facilities.
WP4 – European Neutron and Muon Schools (NaMES)
More than 1500 European early career researchers received training via the NaMES schools since the start of the project. This training is of immense value to the Neutron and Muon science communities, providing, in many cases, access to instrumentation at central facilities in a training and learning environment. This WP will continue to ensure that the European neutron and muon schools continue to improve their output by regular exchange of information and coherent organization and publicity. A follow-up of the future career paths of those trained under the NaMES programme has not been done so far, but school directors state that the students create groups in the different social networks.
WP5 – Integrated User Access
The work done in WP5 has stimulated further studies of harmonized proposal forms and procedures between the neutron and muon facilities. With the demonstration of software package prototypes to handle harmonized proposals and review procedures, it can pave the way to an easier and more straightforward access to the facilities and allow users to interact with the neutron and muon facilities within a common framework for integrated user registration, including cross-facility, beam time access. Results of the WP contain the basis for next steps to implement harmonized proposal forms and administrative processes within the next TNA project of the neutron and muon facilities.
WP6 – Standards for Data Analysis Software
This work-package aims to show that a common software solution can be shared across neutron/muon facilities. The chosen solution, here Mantid, has been used as a prototype infrastructure for this purpose, but other initiatives with similar standards could also be envisaged. Our reports and produced code can be used by any group producing scientific software, and more specifically in the neutron/muon user community. Scientists in the EU can benefit from a shared solution by lowering the learning curve when travelling across facilities. It is hoped that a well-designed, unified software can help to attract more scientists to neutron/muon facilities.
WP17 – Muon Spectroscopy JRA
Key analysis routines identified through JRA work have been implemented; codes, such as a GUI for the analysis of Avoided Level Crossing measurements, are now in regular use at the facilities. Data analysis methods that create a link with simulation codes have been investigated, with a number of examples (such as the quantum mechanical evaluation of spin systems) being developed. Activities in this first task area have made it easier for scientists to extract key results from their data. Discussions at the ‘Future Facilities’ workshop are already proving valuable for opinion forming by those considering funding for new muon facilities, whilst the positive outcome from the concept study for a muon micro-beam could lead the future development of a novel µSR facility. The evaluation of APD-based detectors for pulsed muon sources is particularly opportune, as a design study is currently underway to develop a next generation high density detector array for the MuSR instrument at ISIS.
WP18 – Imaging JRA
Through this research and development activity, new techniques and modelling tools will be made available for a large number of users from the large communities of the nano-magnetism, engineering and generally from materials science.
This project is developing new methods which can provide information on material and magnetic systems which are not accessible using any other experimental technique.
External laboratories (besides neutron facilities) are already involved in the developing and optimizing of the new techniques in respect to their needs for tackling actual scientific problems.
WP19 – Advanced Methods and Techniques JRA
The software to optimize neutron guides depending on many parameters has been developed and tested. It will allow to find the optimal design of the optics for focusing onto sub mm3 samples under extreme conditions of novel neutron instruments in an efficient way. Simulations of the performance of optimized multi-channel guides for the ILL instruments IN5 and ThALES have been performed. They will allow to take a decision about the optics to be implemented in these instruments. The conceptual design of three instruments for extreme conditions neutron experiments has been achieved: first, one for pulsed sources, versatile, capable of operating with short and long pulses and in three different modes (diffraction, spectroscopy, and SANS); second, XtremeD, devised to work at high pressure and/or high magnetic field at constant sources, will be built at ILL; and third, EXPRESSO, an instrument optimized for high pressures and the long pulse characteristic of the ESS. The instruments will provide extreme conditions scientists with superb tools for their research. Particularly, EXPRESSO should be built at the ESS, where it could optimally exploit the TOF technique and the long-pulse structure. Calculations have shown that such an instrument would deliver dramatic increases in flux, particularly at longer wavelengths.
The MIEZE technique was extended to the use with pulsed sources using an improved electronic control for adopting the MIEZE signal to the pulse length of the source. This allows for the measurement of the quasi-elastic dynamics over a large q-range at the same time contrary to the current used method on reactors where one needs measure the dynamics at different q-values sequentially. This development, which has been tested on a chopped beam of neutrons from a reactor, allowed for the successful proposition of a combined NSE and LNRSE MIEZE instrument for the ESS in Lund. The concepts for new RF coils developed within this project as well can be used to operate such an instrument at much higher frequencies as in current instruments and will eventually lead to the construction of a very powerful and flexible high-resolution Spin Echo Instrument.“
The new chopper array concept for focusing neutrons both in space and time in pulsed sources was developed. The elaborated design rules and identification of critical points of operation as well as identification of limitations in neutronics will in future allow to have a quick start in planning and building of a multichopper system for novel use in chopper instruments. Currently there is no concrete project known, however, illuminating the possibility shows ways towards novel focussing schemes in time and space that can be used in future innovative neutron time-of-flight instruments.
Polarised neutron beams are used in disciplines as diverse as magnetism, soft matter or biology. However, the existing neutron polarising methods imply the filtering of one of the spin states, with a transmission of 50% at maximum. With the purpose of using all neutrons that are usually discarded, we have investigated by means of Monte Carlo simulations a system that splits the neutron beam according to their polarisation, flips them to match the spin direction, and then focuses them at the sample. The simulations show that this is achievable over a wide wavelength range and with an outstanding performance at the price of a more divergent neutron beam at the sample position.
WP20 – Advanced Neutron Tools for Soft and Bio Materials JRA
Soft and bio materials have potentially very high socio-economic impact. Lipid membranes are a core material in this area and significant progress is being made in the intrinsic quality of these samples and their deuteration which enables neutron techniques to provide unique information. Molecular dynamics simulations combined to contrast enhancement techniques give key insights into these experimental studies.
The rate at which samples can be measured and the range of experimental conditions are also crucial to the relevance and effectiveness of experimental studies. New sample environment equipment has therefore been developed in this context: an improved stopped-flow device to study kinetic effects, a combination of in situ light scattering and small angle neutron scattering (SANS) to be able to study a broad range of structures of complex samples, an electric field cell with electrodes out of the sample cell, a humidity chamber to study the hydration of lipid membranes up to 99% humidity, various pressure cells optimized for SANS and Neutron Spin Echo techniques and a sample changer in a cryogen-free cryostat to allow efficient measurements of many samples over a wide temperature range.
WP21 – Detectors JRA
The expected result of this work is the development of two new neutron detector technologies suitable for large area neutron detectors for neutron scattering applications. In the absence of sufficient quantities of 3He at an affordable price, new detector technologies are an essential requirement for both new and existing neutron scattering facilities to realise their full scientific potential. The work carried out at these facilities maps directly onto the European science programme which is addressing concerns including climate change, health care, energy, food safety and security.
List of Websites:
http://nmi3.eu/
