Evaluation of nuclide density by neutron resonance transmission at the NOBORU instrument in J-PARC/MLF

It should be possible to non-destructively estimate nuclide density by analyzing the transmission dips due to the resonance absorption in neutron transmission spectra. In this study performed at the NOBORU instrument in J-PARC/MLF, we evaluated the quality of the neutron resonance transmission measurements and their potential use in the estimation of nuclide density. First, we calculated the emission time distributions of epithermal neutrons by simulation and then fitted the pulse shapes using several kinds of functions to make a response function suitable for the NOBORU instrument. We found that the Cole-Windsor function well reproduced the pulse shape at arbitrary energy. Then, we applied this function to the resonance analysis code REFIT, and found that it was possible to reproduce the resonance shapes. Finally, we performed the transmission measurements at NOBORU and analyzed the resonance dips for Ta, Ag and Cu by the revised REFIT code.