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J. Pereira

J. Pereira. b -decay studies of r-process nuclei near 137 Sb. Jorge Pereira NSCL/MSU Frontiers 2005, MSU, August 2005. J. Pereira. Some recent r-process motivated experiments.

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J. Pereira

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

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

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

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

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

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

  7. J. Pereira Analysis of b-decay half-lives T1/2=1449±46 msec T1/2=1450±30 msec T1/2=530±5 msec T1/2=530±20 msec T1/2=1775±19 msec T1/2=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 238U at 750MeV/u) on208Pb have been separated and identified in the FRS (including 134Sn, 136Sn, 137Sb and 142Te 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 • Pn values must be determined

  10. J. Pereira Collaborators R. Kessler (Diploma Thesis), Universität Mainz 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

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

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