Intermediate-energy Coulomb excitation measurements are performed on the N≥40 neutron-rich nuclei 66, 68Fe and 64Cr. The reduced transition matrix elements providing a direct measure of the quadrupole collectivity B(E2; 2+1→ 0+1) are determined for the first time in 68Fe42 and 64Cr40 and confirm a previous recoil distance method lifetime measurement in 66Fe40. The results are compared to state-of-the-art large-scale shell-model calculations within the full fpgd neutron orbital model space using the Lenzi-Nowacki-Poves-Sieja effective interaction and confirm the results of the calculations that show these nuclei are well deformed.
Copyright © 2013 The American Physical Society. This article first appeared in Physical Review Letters 110, no. 24 (June 13, 2013): 242701: 1-42701: 5. doi:10.1103/PhysRevLett.110.242701.
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Crawford, H. L., R. M. Clark, P. Fallon, A. O. Macchiavelli, T. Baugher, D. Bazin, C. W. Beausang, J. S. Berryman, D. L. Bleuel, C. M. Campbell, M. Cromaz, G. De Angelis, A. Gade, R. O. Hughes, I. Y. Lee, S. M. Lenzi, F. Nowacki, S. Paschalis, M. Petri, A. Poves, A. Ratkiewicz, T. J. Ross, E. Sahin, D. Weisshaar, K. Wimmer, and R. Winkler. "Quadrupole Collectivity in Neutron-Rich Fe and Cr Isotopes." Physical Review Letters 110, no. 24 (June 13, 2013): 242701: 1-42701: 5. doi:10.1103/PhysRevLett.110.242701.