Constraining the calculation of U234,236,238(n,γ) cross sections with measurements of the γ -ray spectra at the DANCE facility

Abstract

The cross section for neutron capture in the continuum region has been difficult to calculate accurately. Previous results for $^{238}\mathrm{U}$ show that including an $M1$ scissors-mode contribution to the photon strength function resulted in very good agreement between calculation and measurement. This paper extends that analysis to $^{234,236}\mathrm{U}$ by using $\ensuremath{\gamma}$-ray spectra measured with the Detector for Advanced Neutron Capture Experiments (DANCE) at the Los Alamos Neutron Science Center to constrain the photon strength function used to calculate the capture cross section. Calculations using a strong scissors-mode contribution reproduced the measured $\ensuremath{\gamma}$-ray spectra and were in excellent agreement with the reported cross sections for all three isotopes.