Neutron-capture cross-section measurements of ${}^{136}\mathrm{Xe}$ between 0.4 and 14.8 MeV

Fast-neutron-capture cross-section data on ${}^{136}\mathrm{Xe}$ have been measured with the activation method between 0.4 and 14.8 MeV. The cross section was found to be of the order of 1 mb at the eleven energies investigated. This result is important to interpret potential neutron-induced backgrounds in the enriched xenon observatory and KamLAND-Zen neutrinoless double-$\beta$ decay searches that use xenon as both source and detector. A high-pressure sphere filled with ${}^{136}\mathrm{Xe}$ was irradiated with monoenergetic neutrons produced by the reactions ${}^3$H($p,n$)${}^3$He, ${}^2$H($d,n$)${}^3$He, and ${}^3$H($d,n$)${}^4$He. Indium and gold monitor foils were irradiated simultaneously with the ${}^{136}\mathrm{Xe}$ to determine the incident neutron flux. The activities of the reaction products were measured with high-resolution $\gamma$-ray spectroscopy. The present results are compared to predictions from ENDF/B-VII.1 and TENDL-2012.

Figure 1

Schematic of experimental arrangement for ${}^{136}\mathrm{Xe}$($n,\gamma$)${}^{137}$Xe cross-section measurements using the ${}^2$H($d,n$)${}^3$He reaction.

Figure 2

Portion of $\gamma$-ray spectra collected for the ${}^{136}\mathrm{Xe}$ target after activation with 1.85 MeV neutrons. The $\gamma$-ray line at 455.49 keV associated with the decay of ${}^{137}$Xe is indicated.

Figure 3

Decay curve for the 455.49 keV $\gamma$-ray line of ${}^{137}$Xe measured at $E{}_n=3.34$ MeV.

Figure 4

Excitation function of the ${}^{136}\mathrm{Xe}$($n,\gamma$)${}^{137}$Xe capture cross section. The horizontal bars indicate the neutron energy spread. The shaded area below 0.5 MeV is part of the ENDF/B-VII.1 evaluation.