Two-quantum radiative thermal neutron capture inH1

Abstract

A value of (-5.2±6.4) μb has been obtained for the cross section of the two-quantum radiative thermal neutron capture in hydrogen for the energy region $330<\mathrm{}{E}_{\gamma 1},E_{\gamma 2}<1890\mathrm{}$ keV. Restriction of the evaluation to a $\gamma$ energy range from 700 to 1520 keV yields (-0.4±3.0) μb. The present results are weighted averages from several coincidence experiments performed with various types of detectors. In one experiment, using two NaI(Tl) detectors, special care was taken to cover also the region of lower $\gamma$-ray energies ($233<\mathrm{}{E}_{\gamma 1},E_{\gamma 2}<2017\mathrm{}$ keV), since here the most severe discrepancy to theoretical predictions is indicated by an earlier measurement. The existing data reject a hypothesis concerning nonorthogonality of the ${}_{}{}^3{}_{}{}^{}S_1^{}{}_{}{}^{}$ neutron-proton capturing and the deuteron ground state. Due to use of a ${\mathrm{H}}_2$O target from the present measurements at the same time the total cross section for the reaction ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$($n$,$\gamma$)${}_{}{}^{17}{}_{}{}^{}\mathrm{O}$ could be determined as (187±10) μb.