No abstract

No abstract

Abstract.We have measured precise thermal neutron capture γ-ray cross sections σ γ for all stable Palladium isotopes with the guided thermal neutron beam from the Budapest Reactor. The data were compared with other data from the literature and have been evaluated into the Evaluated Gamma-ray Activation File (EGAF) [1]. Total radiative neutron capture cross-sections σ 0 can be deduced from the sum of transition cross sections feeding the ground state of each isotope if the decay scheme is complete. The Palladium isotope decay schemes are incomplete, although transitions deexciting low-lying levels are known for each isotope. We have performed Monte Carlo simulations of the Palladium thermal neutron capture de-excitation schemes using the computer code DICEBOX [2]. This program generates a level scheme where levels below a critical energy E crit are taken from experiment, and those above E crit are calculated by a random discretization of an a priori known level density formula ρ(E, J π ). Level de-excitation branching intensities are taken from experiment for levels below E crit and the capture state, or calculated for levels above E crit assuming an a priori photon strength function and applying allowed selection rules and a Porter-Thomas distribution of widths. The calculated feeding to levels below E crit can then be normalized to the measured cross section deexciting those levels to determine the total radiative neutron cross-section σ 0 . In this paper we have measured σ 0 [ 102 Pd(n,γ)]=0.9±0. We have also determined from our statistical calculations that the neutron capture state in 107 Pd is best described as 2 + (60%)+3 + (40%). Agreement with literature values was excellent in most cases. We found significant discrepancies between our results for 102 Pd and 110 Pd and earlier values that could be resolved by re-evaluation of the earlier results.

No abstract

Partial γ-ray production cross sections and the total radiative thermal-neutron capture cross section for the 185 Re(n, γ) 186 Re reaction were measured using the Prompt Gamma Activation Analysis facility at the Budapest Research Reactor with an enriched 185 Re target. The 186 Re cross sections were standardized using well-known 35 Cl(n, γ) 36 Cl cross sections from irradiation of a stoichiometric nat ReCl3 target. The resulting cross sections for transitions feeding the 186 Re ground state from low-lying levels below a cutoff energy of Ec = 746 keV were combined with a modeled probability of ground-state feeding from levels above Ec to arrive at a total cross section of σ0 = 111(6) b for radiative thermal-neutron capture on 185 Re. A comparison of modeled discrete-level populations with measured transition intensities led to proposed revisions for seven tentative spin-parity assignments in the adopted level scheme for 186 Re. Additionally, 102 primary γ-rays were measured, including 50 previously unknown. A neutron-separation energy of Sn = 6179.59(5) keV was determined from a global least-squares fit of the measured γ-ray energies to the known 186 Re decay scheme. The total capture cross section and separation energy results are comparable to earlier measurements of these values.