Determination of the29Si level density from 3 to 22 MeV

Abstract

The level density of ${}^{29}$Si has been studied over an excitation energy range of 3 to 22 MeV. Three techniques were used to derive level density values from experimental data. In the region of resolved levels, results were obtained from level counting while neutron resonance data were used in the region of slightly overlapping levels near the neutron binding energy. At the highest excitation energies, characterized by strongly overlapping levels, Ericson theory was employed to deduce level densities by examining energy-dependent fluctuations in cross sections. Three reactions yielding the same compound nucleus, ${}^{29}$Si, were investigated. Partial cross sections from ${}^{28}$Si($n,p$), ${}^{28}$Si($n$,\ensuremath{\alpha}), and ${}^{27}$Al($d,n$)${}^{28}$Si reactions were measured with good experimental resolution and statistical accuracy. From these cross sections, level densities were extracted using the two independent methods proposed by Ericson. Reasonable agreement was found among level densities derived from the two Ericson methods. Values obtained are also fairly consistent with those of various predictions and theoretical models.