Analysis of Gd(n,gamma) reaction with 155, 157 and natural Gd targets taken with JPARC-ANNRI and development of Gd(n,gamma) decay model for Gd-doped neutron/neutrino detectors

The importance of a good model for the g-ray energy spectrum from the radiative thermal neutron capture on Gadolinium (Gd) is specially increased in the present era of Gd-enhanced ¯ ne-search detectors. Its an essential prerequisite for MC studies to evaluate the neutron tagging efficiency, in order to enhance signal sensitivity in the Gd-loaded ¯ ne-search detectors. The g-ray spectra produced from the thermal neutron capture on enriched gadolinium targets (155Gd, 157Gd and Natural Gd) in the energy range 0.11 MeV to 8.0 MeV, were measured using the ANNRI Germanium Spectrometer at MLF, J-PARC. Based on the data acquired and a GEANT4 simulation of the ANNRI detector, we reported the energy spectrum of 157Gd(n, g) and developed a g-ray emission model of 157Gd(n, g) in our previous publication. We now present the analysed data of 155Gd(n, g) and natGd(n, g) reactions, the energy spectra of g-rays and an improved model for 155Gd(n, g), 157Gd(n, g) and natGd(n, g) reactions. The consistency of the results from the devised model is checked among all the 14 germanium crystals, at the level of 15% spectral shape deviation at 0.2 MeV binning.