Characterization of 22 and 33 MeV quasi-monoenergetic neutron fields for detector calibration at CYRIC

At high energy accelerators, in aircraft and spacecraft, neutron measurement with energies higher than 20 MeV is a recent demand. In this study, we developed quasi-monoenergetic neutron fields with peak energies of 22 and 33 MeV using the 7Li(p,n)7Be reaction at the Cyclotron and Radioisotope Center of Tohoku University (CYRIC). The absolute peak neutron fluences and spectra were measured with the proton recoil telescope (PRT), the lithium target activation method, and the time-of-flight method using liquid scintillator. Moreover, we characterized two types of relative fluence monitors, NE213 and a 232Th fission chamber in the neutron field. We could therefore obtain neutron fields having less than 5% fluence accuracy, which we aimed for, and clarified that neutron detector calibration can be performed with good precision (≤7%). (orig.)