Experimental Evaluation of Energy Resolutions for Pulsed Neutron Beam in the KURNS-LINAC

In this study, experimental evaluations for the energy resolution of pulsed neutron flux in the neutron path were carried out. The capture gamma-rays from a Ta-181 sample were measured by BGO detectors with a TOF method, and the TOF spectra for well-known resonances were obtained. The energy resolution was evaluated by comparing a full width at half maximum of the Ta-181 resonances in the JENDL-4.0. In order to obtain relationships between the energy resolution and the pulsed neutron beam width, the measurements were carried out with the pulsed neutron beam width of 4 μsec, 1 μsec and 0.1 μsec, respectively. As the experimental results, the energy resolution of neutron energy range from 4 eV to 125 eV corresponding to each pulse width were evaluated. For example, the energy resolution at 4.28 eV (Ta-181 first resonance peak) was about 0.5 % for a pulse width of 4 μsec.