1. J. Pereira  -decay studies of r-process nuclei near 137 Sb Jorge Pereira NSCL/MSU Frontiers 2005, MSU, August 2005

2. J. Pereira Some recent r-process motivated experiments GSI (in-flight fission) Half-lives, P n values Schatz et al. ISOLDE (ISOL) Decay spectroscopy Dillmann, Kratz et al. GSI (in-flight fission) Masses (IMS) Matos, Scheidenberger et al. GANIL (fragmentation) Decay spectroscopy Sorlin et al. ANL/CPT (Cf source) Re-measured masses with high precision Clark, Savard et al. ORNL (ISOL) (d,p) and Coulex MSU/NSCL (fragmentation) Half-lives, P n values Hosmer et al. Montes et al.

3. J. Pereira A=130 abundance peak Freiburghaus, et al. 1999 ETFSI-1 (Pearson, et al. 1996) ETFSI-Q (Aboussir, et al. 1995) The  -decay half-lives and P n values are crucial to understanding the r-process - Closed Shell - Waiting point nuclei -  - decay measurement

4. J. Pereira Production of n-rich nuclei around 132 Sn by projectile-fission of 238 U @ 750MeV/u on 208 Pb 238 U accelerated up to 750MeV/u In-flight isotopic separation with the FRS

5. Multiwire Proportional Counter (MWPC) MUSIC Chamber Scintillator Degrader Collimator Silicon Detectors (veto) Silicon Stack (implantation region) Mainz Neutron Long Counter beam  neutron J. Pereira  -decay properties of n-rich U-fission fragments

6. J. Pereira Analysis of  -decay half-lives Identified fragmentsImplanted fragments After implantation: Position-correlated decay-events observed within correlation time (10 sec)

7. J. Pereira Analysis of  -decay half-lives T 1/2 =1449±46 msec T 1/2 =1450±30 msec T 1/2 =530±5 msec T 1/2 =530±20 msec T 1/2 =1775±19 msec T 1/2 =2490±50 msec !!!

8. J. Pereira The background problem Decay-curves fits were done assuming constant background “High-energy” decay-events follow spill beam pattern Light-particles (Beam-induced background) Background must be calculated on a time-dependent basis

9. J. Pereira Outlook n-rich fission fragments produced in 238 U at 750MeV/u) on 208 Pb have been separated and identified in the FRS (including 134 Sn, 136 Sn, 137 Sb and 142 Te waiting points) Position correlated decay-events were measured after implantation events within a correlation time of 10 sec Background determination (per detector, strip and settinig) on a time-dependent basis (IN PROGRESS) Half-lives will be determined with MLH-method P n values must be determined

10. J. Pereira Collaborators P.Santi, H. Schatz, NSCL F. Attallah, H. Geissel, M. Hausmann, M. Hellström, G. Münzenberg, C. Scheidenberger, K. Schmidt, K. Sümmerer, GSI H. Mahmud, P.J. Woods, University of Edinburgh J. Stadlmann, Universität Giessen M.N. Mineva, Lund University M. Hannawald, K.-L. Kratz, B. Pfeiffer, Universität Mainz T. Faestermann, R. Schneider, A. Stolz, E. Wefers, TU München U. Giesen, University of Notre Dame R. Kessler (Diploma Thesis), Universität Mainz

11. J. Pereira  -decay studies of n-rich nuclei around 137 Sb at GSI Electromagnetic-induced fission of 238 U on 208 Pb provides maximum productions of n-rich nuclei around 132 Sn e.g. 238 U + 208 Pb T.Enqvist et al., Nucl. Phys. A658 (1999) 47 Isotopic separation of fission fragments: in-flight separation Transmission: Better at high energies Very low for high-mass fission fragments SIS + FRS at GSI: Fission reaction 238 U(750MeV/u)+ 208 Pb at GSI