Low-energy enhancement and fluctuations of γ-ray strength functions in 56,57Fe: test of the Brink-Axel hypothesis

Nuclear level densities and γ-ray strength functions of 56,57Fe have been extracted from proton-γ coincidences. A low-energy enhancement in the γ-ray strength functions up to a factor of 30 over common theoretical E1 models is confirmed. Angular distributions of the low-energy enhancement in 57Fe in...

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Bibliographic Details
Published in:Journal of physics. G, Nuclear and particle physics Nuclear and particle physics, 2017-04, Vol.44 (6)
Main Authors: Larsen, A C, Guttormsen, M, Blasi, N, Bracco, A, Camera, F, Campo, L Crespo, Eriksen, T K, Görgen, A, Hagen, T W, Ingeberg, V W, Kheswa, B V, Leoni, S, Midtbø, J E, Million, B, Nyhus, H T, Renstrøm, T, Rose, S J, Ruud, I E, Siem, S, Tornyi, T G, Tveten, G M, Voinov, A V, Wiedeking, M, Zeiser, F
Format: Article
Language:eng ; nor
Subjects:
angular distributions
Brink hypothesis
iron
level density
strength function
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Summary:Nuclear level densities and γ-ray strength functions of 56,57Fe have been extracted from proton-γ coincidences. A low-energy enhancement in the γ-ray strength functions up to a factor of 30 over common theoretical E1 models is confirmed. Angular distributions of the low-energy enhancement in 57Fe indicate its dipole nature, in agreement with findings for 56Fe. The high statistics and the excellent energy resolution of the large-volume LaBr3(Ce) detectors allowed for a thorough analysis of γ strength as function of excitation energy. Taking into account the presence of strong Porter-Thomas fluctuations, there is no indication of any significant excitation energy dependence in the γ-ray strength function, in support of the generalized Brink-Axel hypothesis.
ISSN:0954-3899
1361-6471
DOI:10.1088/1361-6471/aa644a