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The gamma-strength functions and level densities of in the quasi-continuum of 147,149Sm isotopes have been extracted from particle-gamma coincidences using the Oslo method. The nuclei of interest were populated via (p,d) reactions on pure 148,150Sm targets and the reaction products were recorded by the HYPERION array. An upbend in the gSF has been observed. The systematic analysis of the gSF for a range of Sm isotopes show that the scissors mode and the upbend compete with each other. Shell model calculations show a very good agreement with the experimental gSFs and confirm the competition between the upbend and scissors mode.

Even tin isotopes of mass number A = 108-124 are calculated with realistic interactions in the generalized-seniority approximation of the nuclear shell model. For each nucleus, we compute the lowest 10 000 states (5000 of each parity) up to around 8 MeV in excitation energy, by allowing as many as four broken pairs. The lowest 50 eigen energies of each parity are compared with the exact results of the large-scale shell-model calculation. The wave functions of the midshell nuclei show a clear pattern of the stepwise breakup of condensed coherent pairs with increasing excitation energy. We also compute in the canonical ensemble the thermal properties-level density, entropy, and specific heat-in relation to the thermal pairing phase transition., QC 20161118

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.

New energy-, spin-and parity-dependent nuclear level densities based on the microscopic combinatorial model are proposed for practical applications. The combinatorial model includes a detailed microscopic calculation of the intrinsic state density and of the rotational enhancement factor, but a phenomenological treatment of the vibrational effect. The vibrational description has been improved using a boson partition function to construct phonons' state densities which are then folded in with the incoherent particle-hole densities. The present model is shown to predict the experimental s-wave neutron resonance spacings with a degree of accuracy comparable to that of the best global models available., SCOPUS: cp.p, info:eu-repo/semantics/published