Abstract
The nuclear level densities of and the -ray strength functions of below the neutron separation energy are extracted with the Oslo method using the (,) and (,) reactions. The level-density function of displays steplike structures. The microcanonical entropies are deduced from the level densities, and the single neutron entropy of is determined to be . Results from a combinatorial model support the interpretation that some of the low-energy steps in the level density function are caused by neutron pair breaking. An enhancement in all the -ray strength functions of , compared to standard models for radiative strength, is observed for the -ray energy region of MeV. These small resonances all have a centroid energy of MeV and an integrated strength corresponding to of the classical Thomas-Reiche-Kuhn sum rule. The Sn resonances may be due to electric dipole neutron skin oscillations or to an enhancement of the giant magnetic dipole resonance.
5 More- Received 30 March 2010
DOI:https://doi.org/10.1103/PhysRevC.81.064311
©2010 American Physical Society