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Keywords:

radioactive beams, relativistic coulomb excitation, transition probabilities, shell model, Science & Technology, Physical Sciences, Astronomy & Astrophysics, Physics, Nuclear, Physics, Particles & Fields, Physics, SHELL, INTERMEDIATE, 0105 Mathematical Physics, 0201 Astronomical and Space Sciences, 0202 Atomic, Molecular, Nuclear, Particle and Plasma Physics, Nuclear & Particles Physics, 49 Mathematical sciences, 51 Physical sciences

Abstract:

The first excited 2 + states in 54,56,58 Cr were populated by Coulomb excitation at relativistic energies and γ rays were measured using the RISING setup at GSI. For 56 Cr and 58 Cr the B( E2 , 2 + 1 → 0 + ) values relative to the previously known B( E2 ) value for 54 Cr are determined as 8.7(3.0) and 14.8(4.2) W.u., respectively. The results are consistent with a subshell closure at neutron number N = 32 which was already indicated by the higher energy of the 2 + 1 state in 56 Cr. Recent large-scale shell model calculations using effective interactions reproduce the trend in the excitation energies, but fail to account for the minimum in the B( E2 ) values at N = 32.  2005 Elsevier B.V. All rights reserved