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Shape Coexistence and the N=28 Shell Closure Far from Stability |
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| Authors: | F Sarazin H Savajols W Mittig F Nowacki N A Orr Z Ren P Roussel-Chomaz G Auger D Baiborodin A V Belozyorov C Borcea E Caurier Z Dlouhý A Gillibert A S Lalleman M Lewitowicz S M Lukyanov F de Oliveira Y E Penionzhkevich D Ridikas O Tarasov H Sakuraï A de Vismes |
| Institution: | (1) GANIL, BP 5027, 14076 Caen Cedex 05, France;(2) Laboratoire de Physique Théorique, 67084 Strasbourg Cedex, France;(3) LPC, ISMRA et Université de Caen, 14050 Caen Cedex, France;(4) Nucl. Phys. Inst., ASCR, 250 68 Řež, Czech Republic;(5) FLNR, JINR, Dubna, P.O. Box 79, 101 000 Moscow, Russia;(6) IAP, P.O. Box MG-6, 76900 Bucharest-Magurele, Romania;(7) IRES, Université Louis Pasteur, BP 28, 67037 Strasbourg Cedex 2, France;(8) CEA/DSM/DAPNIA/SPhN, CEN Saclay, 91191 Gif-sur-Yvette, France;(9) RIKEN, Wako, Saitama 351-01, Japan |
| Abstract: | A mass measurement experiment by a time of flight method with the SPEG spectrometer at GANIL has been performed to investigate the N=20 and N=28 shell closures far from stability. The masses of 31 neutron-rich nuclei in the range A=29–47 have been measured. The precision of 19 masses has been significantly improved and 12 masses were measured for the first time. The neutron-rich Cl, S and P isotopes are seen to exhibit a change in shell structure around N=28. Comparison with shell model and relativistic mean field calculations demonstrate that the observed effects arise from deformed prolate ground state configurations associated with shape coexistence. The evidence of an isomeric state in the 43S and its interpretation by a shell model calculation confirm the analysis of the masses and constitutes the first evidence of the predicted shape coexistence around N=28. This revised version was published online in July 2006 with corrections to the Cover Date. |
| Keywords: | mass measurement exotic nuclei shell closures spectrometer |
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