Measurement of Neutron Kerma Factors at 18, 23, and 25 MeV

absorbed activation additional alpha particles angle assumed average background beam breakup neutrons calculated calibration carbon caused cavity cell charged particle collection compared contaminating contribution convert corrected corresponding cosmic rays counter event size-weighted cross section cylindrical detector determined deuteron diameter distribution edge effect efficiency electron elements empty target error evaluations event size event size-weighted dose experiment Figure flux gamma rays incident integral ionization iron irradiation kerma factor measurements length light lower mass material maximum method MeV cm² MeV neutron energy neutron fluence neutron interactions neutron kerma factors neutron spectrum nuclear nucleus oxygen peak positioned present produced proportional counter event proton pulse height radiation range ratio reaction recoil relative samples scattering scintillator shown shows silicon size-weighted dose spectra spherical stopping power subtracted Table teflon threshold time-of-flight tritium uncertainty unit values volume wall ZrO2