Neutron Filtering System for Neutron Capture Cross Section Measurement at the ANNRI beamline of MLF/J-PARC

A neutron filtering system has been designed and implemented in the Accurate Neutron -Nucleus Reaction Measurement Instrument (ANNRI) beamline in the Materials and Life Science (MLF) facility of the Japan Proton Accelerator Research Complex (J-PARC) to bypass the effect of the double -bunch mode of J-PARC by molding the incident neutron flux into quasi-monoenergetic neutron beams. Filter assemblies using Fe, Si and Cr as filter materials were analyzed by means of experimental analysis, together with Monte Carlo simulations. The characteristics of the filtered neutron beam are presented and discussed alongside its viability in future applications for neutron cross-section measurements in the keV neutron region.