Final Report Summary - HEAVYRIB (Nuclear structure studies of neutron-deficient nuclei in light Pb region using radioactive ion beams)
The first part of experiment was run in August 2010, in which data for 192Pb nucleus was collected. The second part was run in the beginning of June 2011. The Pb nuclei were extracted from the ISOLDE UCx target and the post-accelerated beam was delivered to MINIBALL target position. At MINIBALL, the Pb nuclei were Coulomb excited in inverse kinematics using secondary 112Cd target. The MINIBALL Ge-detector array was used to detect gamma-rays de-exciting levels under investigation. Both scattered projectiles and target recoils were detected using an annular double sided silicon strip detector (CD) positioned on the beam axis after the secondary target. For the first time, such an exotic Pb beam was post-accelerated. Data are still under analysis, but preliminary results show that the collectivity (B(E2)-values) of the first 2+ states in 188-198Pb isotopes can be deduced. Data will also allow to study the systematic behaviour of mixing between different shape coexisting structures.
One of the objectives of this proposal was to study and develop new methods for manipulation and preparation of radioactive beams at REX-ISOLDE. The fellow developed a device to monitor the shape of the REX-LINAC macro pulse. This will be an important tool when setting up the slow extraction from REX-EBIS.
In the endeavour to understand nuclear structure and related phenomena, in-beam gamma-ray spectrometers have been important tools for decades. However, a gamma-ray spectrometer can provide only partial information of nuclear de-excitation processes as it can not detect electrons originating from internal conversion. The fellow has initiated a project that aims to combine the MINIBALL array with electron spectrometer. The simultaneous detection of conversion electrons and gamma-rays at MINIBALL would not only provide information on shape coexistence in light Pb isotopes, but has also considerable interest from the MINIBALL community.