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09.05.2012

 

NUSTAR Seminar

NUSTAR Seminar: Dr. habil Hans-Jürgen Wollersheim, Gammaspectroscopy group, GSI:"PreSPEC - Gamma-spectroscopy on the way towards NUSTAR", Theory Seminar Room, 11:00 am, GSI


E-mail: h.j.wollersheim(at)gsi.de

With the establishment of FAIR, the nuclear structure community is now heavily committed to a future programme of in-flight and decay gamma-ray spectroscopy of highly exotic nuclei produced from the SUPER-FRS. The PreSPEC project was established as a pre-cursor, which builds on the successful RISING results.
In a first campaign high-resolution in-flight spectroscopy of exotic nuclear beams will be performed at relativistic energies (β~0.4-0.5). These nuclei will be produced in fragmentation or fission reactions of relativistic projectiles delivered from the UNILAC-SIS accelerator complex. The GSI Fragment Separator (FRS) will be employed to select the fragments of interest. A thick secondary target positioned at the final focal plane of the FRS will be used for Coulomb excitation or (secondary) fragmentation of the separated nuclei. Gamma-rays emitted in these reactions will be detected by the AGATA and HECTOR arrays. Compared to the RISING Cluster array the tracking ability of AGATA allows to place the array much closer to the target, thus gaining in gamma-ray efficiency and peak-to-background performance, while at the same time also improving on the achievable energy resolution for in-flight gamma-ray emission. The fragments produced at the secondary target will be identified and tracked by the Lund-York-Cologne Calorimeter Array (LYCCA), a HISPEC development already available in its early implementation LYCCA-0.
In the fast-beam RISING campaign, relativistic Coulomb excitation, two-step fragmentation reactions and virtual photon scattering were all successfully used. The gained experience allowed to select PreSPEC-AGATA experiments which comprises exclusively topics of major significance in contemporary nuclear structure physics. These include the evolution (and modification) of shell structure with increasing neutron excess, the breakdown of isospin symmetry, the evaporation of the limits of nuclear existence near the drip-lines, the onset of collectivity in yet unexplored mass regions and the study of electric and magnetic dipole strength in nuclei.
In the present contribution results from recent fast-beam experiments will be presented and the proposed scientific programme will be discussed.

The talk can be downloaded here.

For further informations please contact s.heinz@gsi.de


  

  

 
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