Thermal neutron capture cross sections forO16,17,18andH2

Abstract

Thermal neutron capture γ-ray spectra for 16,17,18 16,17,18 O(n,γ) reactions were measured. Absolute transition probabilities were determined for each reaction by a least-squares fit of the γ-ray intensities to the decay schemes after accounting for the contribution from internal conversion. The transition probability for the 870.76 keV γ-ray from 16 O(n,γ) was measured as Pγ (871)=96.6±0.5% and the thermal neutron cross section for this γ-ray was determined as 0.164±0.003 mb by internal standardization with multiple targets containing oxygen and stoichiometric quantities of hydrogen, nitrogen, and carbon whose γ-ray cross sections were previously standardized. The γ-ray cross sections for the 17,18 O(n,γ) and 2 H(n,γ) reactions were then determined relative to 870.76-keV γ-ray cross section after accounting for the isotopic abundances in the targets. We determined the following total radiative thermal neutron cross sections for each isotope from the γ-ray cross sections and transition probabilities; σ0(

Thermal neutron radiative cross sections forLi6,7,Be9,Firestone1, Révay2 2016Phys. Rev. CSelf Cite

“…Previously we have published the total radiative thermal neutron capture cross sections for 2 H and 16,17,18 O [6] and in this work we discuss our measurements of the 6,7 Li, 9 Be, 10,11 B, 12,13 C, and 14,15 N cross sections.…”

“…Each target was analyzed by PGAA to search for γ-rays from target impurities and no significant impurities were found for the targets used in these experiments. The primary comparator for this work is the 2223-keV transition produced by the 1 H(n,γ) reaction where σ γ =332.5±0.7 mb [6,16]. The secondary standards 12 C and 14 N were calibrated with respect to hydrogen as discussed below.…”

“…The error consists of 0.12 mb statistical uncertainty and 0.03 mb calibration uncertainty. This value is consistent with previous measurements and the adopted value from Mughabghab [16] that are summarized in Table XV. H. 6,7 Li cross sections The 6,7 Li cross sections were measured with a 7 LiF target enriched to 98% in 7 Li and a natural Li 2 CO 3 target. The γ-ray energies, intensities and transition probabilities for both reactions are summarized in Table XVI TABLE XVI: 6,7 Li(n,γ) energies, intensities, and γ-ray cross sections measured on a LiF target enriched to 98% in 7 Li and a natural Li2CO3 target.…”

Developments in capture-γlibraries for nonproliferation applications

“…New and improved neutron-capture γ -ray line data were used to upgrade nine ENDF libraries: 6,7 Li, 11 B, 19 F, 23 Na, 27 Al, 28 Si, and 35,37 Cl. These libraries contain improved γ -ray spectroscopic line data necessary for simulations of interrogation systems.…”

Interference effect between neutron direct and resonance capture reactions for neutron-rich nuclei

“…The solid and dashed lines are the results of compound process + direct process + interference effect (Com+Dir+Int) and compound process + direct process (Com+Dir), respectively. The Woods-Saxon potential parameter V is determined so as to reproduce the most recent experimental data of the thermal neutron capture cross section, σ γ (th) = 1.496 b [21] and at E = 64 keV [22] in case of Com+Dir+Int, as mentioned in the previous section. The interference effect plays a significant role from low energy region.…”