Low-energy enhancement in the gamma-ray strength functions of 73,74Ge


Low-energy enhancement in the gamma-ray strength functions of 73,74Ge

Renstrøm, T.; Nyhus, H.-T.; Utsunomiya, H.; Schwengner, R.; Goriely, S.; Larsen, A. C.; Filipescu, A. D. M.; Gheorghe, I.; Bernstein, L. A.; Bleuel, D. L.; Glodariu, T.; Görgen, A.; Guttormsen, M.; Hagen, T. W.; Kheswa, B. V.; Lui, Y.-W.; Negi, D.; Ruud, I. E.; Shima, T.; Siem, S.; Takahisa, K.; Tesileanu, O.; Tornyi, T. G.; Tveten, G. M.; Wiedeking, M.

The gamma-ray strength functions and level densities of 73,74Ge have been extracted up to the neutron separation energy Sn from particle- coincidence data using the Oslo method. Moreover, the gamma-ray strength function of 74Ge above Sn has been determined from photo-neutron measurements; hence these two experiments cover the range of E = 1 - 13 MeV for 74 Ge. The obtained data show that both 73,74 Ge display an increase in strength at low energies. The experimental strength functions are compared with M1 strength functions deduced from average B(M1) values calculated within the shell model for a large number of transitions. The observed low-energy enhancements in 73,74 Geare adopted in the calculations of the 72,73Ge(n,gamma) cross sections, where there are no direct experimental data. Reaction rate calculations for more neutron-rich germanium isotopes are shown to be sensitive to a low-energy enhancement.

Keywords: Nuclear structure; nuclear reactions; strength functiopns; level densities

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Publ.-Id: 22388