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arXiv · 1310.7068

Scissors resonance in the quasi-continuum of Th, Pa and U isotopes

M. Guttormsen·L. A. Bernstein·A. Görgen·B. Jurado·S. Siem·M. Aiche·Q. Ducasse·F. Giacoppo·F. Gunsing·T. W. Hagen·A. C. Larsen·M. Lebois·B. Leniau·T. Renstrøm·S. J. Rose·T. G. Tornyi·G. M. Tveten·M. Wiedeking·J. N. Wilson
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Abstract

The gamma-ray strength function in the quasi-continuum has been measured for 231-233Th, 232,233Pa and 237-239U using the Oslo method. All eight nuclei show a pronounced increase in gamma strength at omega_SR approx 2.4 MeV, which is interpreted as the low-energy M1 scissors resonance (SR). The total strength is found to be B_SR = 9-11 mu_N^2 when integrated over the 1 - 4 MeV gamma-energy region. The SR displays a double-hump structure that is theoretically not understood. Our results are compared with data from (gamma, gamma') experiments and theoretical sum-rule estimates for a nuclear rigid-body moment of inertia.

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M. Guttormsen, L. A. Bernstein, A. Görgen, B. Jurado, S. Siem, M. Aiche, Q. Ducasse, F. Giacoppo, F. Gunsing, T. W. Hagen, A. C. Larsen, M. Lebois, B. Leniau, T. Renstrøm, S. J. Rose, T. G. Tornyi, G. M. Tveten, M. Wiedeking, J. N. Wilson. 2013-10-26. Scissors resonance in the quasi-continuum of Th, Pa and U isotopes. https://doi.org/10.1103/physrevc.89.014302

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