Thermal neutron capture cross sections of the palladium isotopes

Abstract

Precise thermal neutron capture \ensuremath{\gamma}-ray cross sections ${\ensuremath{\sigma}}_{\ensuremath{\gamma}}$ were measured for all elements with $Z=1\text{\ensuremath{-}}83,90$, and 92, except for He and Pm, at the Budapest Reactor. These data were evaluated with additional information from the literature to generate the Evaluated Gamma-ray Activation File (EGAF). Isotopic radiative neutron cross sections can be deduced from the total transition cross section feeding the ground state, ${\ensuremath{\sigma}}_{0}=\ensuremath{\Sigma}{\ensuremath{\sigma}}_{\ensuremath{\gamma}}(\mathrm{GS})$ if the decay scheme is complete. The EGAF file contains partial \ensuremath{\gamma}-ray cross sections for all stable palladium isotopes. None of these decay schemes are complete, although in each case transitions de-exciting low-lying levels are known. We have performed Monte Carlo simulations of the palladium thermal neutron capture decay schemes using the computer code DICEBOX. The simulated populations of low low-lying levels are normalized to the measured ${\ensuremath{\sigma}}_{\ensuremath{\gamma}}$ values from EGAF and the total radiative neutron cross section ${\ensuremath{\sigma}}_{0}$ is obtained. The ${\ensuremath{\sigma}}_{0}$ values derived for the palladium isotopes agree well with previous measurements and were in several cases more precise. Complementary use of \ensuremath{\gamma}-ray cross-section data and Monte Carlo calculations has proven effective in determining both the palladium total radiative cross sections and new nuclear structure information.