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Approaching 78 Ni Along the N=50 Line M.P. Carpenter Argonne National Laboratory

Approaching 78 Ni Along the N=50 Line M.P. Carpenter Argonne National Laboratory. Studies with Gammasphere on neutron rich N~50 nuclei populated in deep inelastic collisions (DIC) using an 82 Se beam on 208 Pb and 238 U thick targets Results on 84 Se and 82 Ge (N=50)

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Approaching 78 Ni Along the N=50 Line M.P. Carpenter Argonne National Laboratory

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  1. Approaching 78Ni Along the N=50 LineM.P. CarpenterArgonne National Laboratory • Studies with Gammasphere on neutron rich N~50 nuclei populated in deep inelastic collisions (DIC) using an 82Se beam on 208Pb and 238U thick targets • Results on 84Se and 82Ge (N=50) • Results on 74Zn (close lying 6+ states). INPC2007 June 6, 2007

  2. How do we access neutron rich isotopes at Gammasphere • Spontaneous fission sources 252Cf, 248Cm • Induced fission of actinide targets. • Deep Inelastic Collisions (DIC) • Fusion Evaporation (evaporated charged particle channels). Distribution of fission fragments from the spontaneous fission of 252Cf.

  3. Results from Gammasphere DIC 48Ca + 238U 32 34 28 1129 R.V.F. Janssens et al., PLB 546, 22 (2002) B. Fornal et al., PRC 70, 064304 (2004)

  4. Neutron States 82 d3/2 h11/2 s1/2 g7/2 d5/2 50 g9/2 40 p1/2 f5/2 28 p3/2 28 f7/2 Is 78Ni doubly magic? T. Otsuka et al., Phys. Rev. Lett. 95, 232502 (2005) N=82 N=50 • Neutron magic-numbers at N=50 and N=82 play an important role in determining the r-process path.

  5. Pushing towards 78Ni along the N=50 line? • Experimental Details • 82Se (610 MeV) + 238U and 208Pb thick targets • g-g-g with Gammasphere • Deep Inelastic excitation • 82Se + 2n + 0p → 84Se • 82Se + 2n - 2p → 84Ge • 82Se – 4p – 4n → 74Zn

  6. Gammasphere at ATLAS : The Present FMA Station Stand Alone Station

  7. Gate: 1455-1087 Results on 84Se (12+) • 3 recent publications on 84Se level structure – DIC (Legnaro), induced fission (Orsay), 252Cf spontaneous fission (Vanderbilt). • All results see only up to 1st 7+ state. • 82Se + 238U with Gammasphere sees up to (12+) (9+) (10+) (7+) (8+) (7+) (7+) 7+ 6+ (5+) 4+ 84Se 2+ 0+

  8. 82Se + 190Os DIC Y.H. Zhang et. al., Phys. Rev. C 70, 024341 (2004) What is reported for 82Ge 82Ge • decay of 82Ga P. Hoff, B. Fogelberg, Nucl. Phys. A 368, 210 (1981)

  9. * * Gate: 1348 keV *64Ni *87Kr * ? * * * 940 * 866 Gate on the 2+-0+ transition in 82Ge 87Kr

  10. (6+) (5+) (4+) 82Ge50 What’s in coincidence with the 1348 and 940? Gate: 938-1348

  11. (12+) (10+) (9+) N=50 Isotones (7+) (7+) (7+) DE = 475 keV (6+) (5+) (4+) 2+ 82Ge 84Se 0+ Level Systematics and Shell Model New T=1 effective interactions for the f5/2p3/2p1/2g9/2 model space A. F. Lisetskiy et al., Phys. Rev. 70, 044314 (2004).

  12. 1.0 Ex (MeV) 0.5 1/2+ 5/2+ Expt Theory 82Ge 1348 keV 82Ge(d,p) and 82Ge at HRIBF 82Ge Couloumb Excitation 2H(82Ge,p)83Ge J.S. Thomas et al., Phys. Rev. C 71, 021302 (2005) E. Padilla-Rodel et al., Phys. Rev. Lett. 94, 122501 (2005)

  13. New levels in 72,74Zn Angular Correlations E2-E1 E2-E2 A. Hecht et al., to be submitted to Phys. Rev. C

  14. Positive parity levels in Zn isotopes Exp. Vs. Theory Calculations by A. J. Lisetskiy (JJ4APN)

  15. Close lying 6+ States in 72,74Ni A. J. Lisetskiy et al., Phys. Rev. C 70, 044314 (2004).

  16. Summary • Data on N=50 nuclei near 78Ni are becoming available • Results are not entirely consistent with shell model. • Important measurement 2+ excitation energy in 78Ni (direct indication if Z=28 gap has closed). • Our data is rich – new information on odd-A nuclei e.g. 83As, 72,74Zn • Also measured DIC with 64Ni + 208Pb, 238U (N. Hoteling – thesis) • Improvements to measurement • Mass Selectivity (PRISMA at Legnaro, Chico at Gammasphere) • One g-ray is sometimes enough to get started but two is better.

  17. Collaborators on 82Se DIC M. P. Carpenter 1, R. V. F. Janssens1, S. Zhu1, B. Fornal2, R. Broda2, A. Galindo-Uribarri3, N. Hoteling4 , A. Ibanez5,T. L. Khoo1, F. G. Kondev6, T. Lauritsen1, C. J. Lister1, E. Padilla-Rodal3,7, D. Seweryniak1, J. P. Ureggo-Blanco7, X. Wang1,8 1Physics Division, Argonne National Laboratory, Argonne, IL 60439 2 Niewodniczanki Institute of Nuclear Physics, PL-31342, Cracow, Poland 3 Oak Ridge National Laboratory, Oak Ridge, TN 37831 4 University of Maryland, College Park, MD 20742 5Instituto de Fisica, UNAM 6Nuclear Engineering Division, Argonne National Laboratory, Argonne, IL 60439 7University of Tennessee, Knoxville, TN 37996 8University of Notre Dame, Notre Dame IN 46556 Also - W. B. Walters (Univ. Maryland), A. Hecht (Maryland/ANL)

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