Tübingen 2003 – scientific programme

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HK: Physik der Hadronen und Kerne

HK 29: Kernphysik/Spektroskopie IV

HK 29.6: Talk

Wednesday, March 19, 2003, 15:30–15:45, A

Neutron-rich nuclei beyond N=28 and the N=40 and 50 shell closure — •H. Grawe¹, J.M. Daugas², G. Georgiev², R. Grzywacz³, M. Lewitowicz², H. Mach⁴, G. Neyens⁵, F. Nowacki⁶, M. Pfützner⁷, M. Sawicka⁷, O. Sorlin⁸, and M. Stanoiu² — ¹GSI,Darmstadt/D — ²GANIL,Caen/F — ³ORNL,Oak Ridge/US — ⁴ISV,Uppsala Univ./S — ⁵IKS,KU Leuven/B — ⁶IReS,Strasbourg/F — ⁷IEP,Warsaw Univ./PL — ⁸IPNO,Orsay/F

The dominant monopole interaction of the spin-flip partners π f_5/2 − ν f_7/2 and π f_5/2 − ν g_9/2 is decisive for the shell structure of neutron-rich nuclei beyond N=28. The weakness and extreme locality of the N=40 shell in ⁶⁸Ni and the persistence of the N=50 shell at ⁷⁸Ni can be traced back to monopole driven migration of selected single particle orbits [1]. Recent experimental data on isomer spectroscopy in ⁶⁷Fe [2], ^70,76Ni [3], ⁷⁸Zn [4]; β-decay of ⁷²Co [5]; g-factors in ⁶⁷Ni, ⁶⁹Cu [6]; Coulomb excitation of ⁶⁸Ni [7]; and ps-lifetimes in ^67,69,70Ni, ⁷¹Cu [8] give evidence for this scenario, which implies new shell structure in light and medium-heavy neutron-rich nuclei. The experimental results are discussed in the frame work of large-scale shell model calculations.

[1] H. Grawe, Proc. Zakopane, 2002, Act. Phys. Pol. B, in print

[2] M. Sawicka et al., Eur. Phys. J. A15, in print

[3] M. Sawicka et al., Proc. NS2002, Padova, Eur. Phys. J. A, in print

[4] J.M. Daugas et al., Phys. Lett. B476, 213 (2000)

[5] R. Grzywacz et al., Proc. NS2002, Berkeley, AIP CP, in print

[6] G. Georgiev et al., J. Phys. G28, 2993 (2002)

[7] O. Sorlin et al., Phys. Rev. Lett. 88, 092501 (2002)

[8] H. Mach et al., Proc. NPDC17, Nucl. Phys. A in print