Resonance analysis of ^147Sm(n,α ) cross sections: Comparison to statistical model calculations and possible indications of nonstatistical effects
Abstract
We have measured the ^147Sm(n,α ) cross section from 3 eV to 500 keV and performed an Rmatrix analysis in the resolved region (E_n< 700 eV) to extract α widths for 104 resonances. We compare the resulting resonance parameters to nuclear statistical model calculations. Comparing average resonance parameters rather than cross sections allows more direct tests of potentials used in the model and hence should offer greater insight into possible improvements. In particular, an improved α +nucleus potential is needed for applications in nuclear astrophysics. The present comparison reveals that confounding influences due to the calculated neutron strength functions, level densities and width fluctuation corrections result in better agreement between theory and experiment when compared as cross sections rather than as alpha widths. This indicates that the α +nucleus potential in the model requires larger modification than previously thought. In addition, comparing the measured to calculated α width ratio for the two possible swave spin states offers insight into the energy dependence of the α +nucleus potential. Finally, the α width distributions show indications of nonstatistical effects.
 Publication:

APS Division of Nuclear Physics Meeting Abstracts
 Pub Date:
 October 2003
 Bibcode:
 2003APS..DNP.GF007K