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

作者：Larsen A C^*; Guttormsen M; Blasi N; Bracco A; Camera F; Campo L Crespo; Eriksen T K; Gorgen A; Hagen T W; Ingeberg V W; Kheswa B V; Leoni S; Midtbo J E; Million B; Nyhus H T; Renstrom T; Rose S J; Ruud I E; Siem S; Tornyi T G; Tveten G M; Voinov A V; Wiedeking M; Zeiser F

来源：Journal of Physics G: Nuclear and Particle Physics , 2017, 44(6): 064005.

DOI：10.1088/1361-6471/aa644a

• level density
• gamma-strength function
• angular distributions
• Brink hypothesis
• iron

Nuclear level densities and gamma-ray strength functions of Fe-56,Fe-57 have been extracted from proton-gamma coincidences. A low-energy enhancement in the gamma-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 Fe-56. The high statistics and the excellent energy resolution of the large-volume LaBr3(Ce) detectors allowed for a thorough analysis of. 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 gamma-ray strength function, in support of the generalized Brink-Axel hypothesis.

• 出版日期2017-6