Freiburg 1999 – scientific programme

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HK: Physik der Hadronen und Kerne

HK 32: Postersitzung / Kernphysik

HK 32.3: Poster

Wednesday, March 24, 1999, 10:15–12:00, Foyer

Nuclear structure from ¹⁰⁰Sn at N≃Z to ⁷⁸Ni at N≫Z. — •M. Górska^1,2, H. Grawe¹, M. Lipoglavšek³, C. Fahlander⁴, A. Axelsson⁵, J. Nyberg⁵, G. de Angelis⁶, A. Gadea⁶, R. Grzywacz^2,7, K. Rykaczewski⁷, M. Lewitowicz⁸, and J.M. Daugas⁸ — ¹GSI Darmstadt, Planckstr. 1, D–64291 Darmstadt, Germany — ²IEP, University of Warsaw — ³J. Stefan Institute, Ljubljana — ⁴Dept. of Physics, Lund University — ⁵TSL, Uppsala University — ⁶INFN, Legnaro — ⁷ORNL, Oak Ridge — ⁸GANIL, Caen

With the recent success in experimental approach to neutron deficient nuclei at ¹⁰⁰Sn [1] and to neutron rich nuclei beyond ⁶⁸Ni [2] it has become feasible to study the shell structure and residual interaction in regions of the nuclidic chart, that were not accessible before. This has been possible by the development of efficient γ-arrays with highly selective ancillary detectors and by exploiting nuclear reactions as deep-inelastic and fragmentation.
The shell structure at N=Z=50 (¹⁰⁰Sn) shows a remarkable similarity to N=Z=28 (⁵⁶Ni), albeit recent experiments on the ¹⁰⁰Sn neighbours ^102,104Sn and ⁹⁸Cd indicate substantial and puzzling deviations in the E2 and E3 polarizability of the magic core [3-5]. New experimental results and their shell model interpretation will be discussed.
The subshell closure at Z=28, N=40 (⁶⁸Ni), as predicted in mean field calculations and expected from the valence mirror nuclei at N=50, Z=40 (⁹⁰Zr), is at variance with experimental evidence on binding energies and shell occupancy in ^69,70Ni [2]. With the increasing amount of data from isomer and β-decay spectroscopy an extrapolation of the single particle structure towards ⁷⁸Ni is within reach [6]. Recent experimental results on ^72,74Ni and ⁷⁸Zn indicate dramatic differences in the structure of the Z=28 neutron ν g_9/2 isotopes below ⁷⁸Ni as compared to the valence mirror N=50 ν g_9/2 isotones below ¹⁰⁰Sn.

[1] H. Grawe et al., Z. Phys. A358, 185 (1997)

[2] R. Grzywacz et al., Phys. Rev. Lett. 81, 766 (1998)

[3] M. Lipoglavšek et al., Z. Phys. A356, 239 (1996)

[4] M. Górska et al., Phys. Rev. C58, 108 (1998)

[5] M. Górska et al., Phys. Rev. Lett. 79, 2415 (1997)

[6] H. Grawe et al., Progr. Part. Nucl. Phys. 38, 15 (1997)