Measurement of neutron kerma factors in C, O, and Si at 18, 23 and 25 MeV

Carbon, oxygen, and silicon kerma factor values were measured at neutron energies of 18-25 MeV using microdosimetric techniques. Small spherical and cylindrical proportional counters served to measure neutron kerma, while detection of the activity induced in Teflon (C2F4)n samples by the 19F(n,2n)18F reaction determined the fast neutron fluence. Deuteron bombardment of a tritium gas target provided a monoenergetic neutron source plus a secondary flux of 0 to 6 MeV neutrons. At each energy, a liquid scintillator-based time-of-flight spectrometer measured the neutron spectrum. In order to correct our measurements for kerma contributed by off-energy neutrons, we combined the secondary neutron spectrum with tabulated energy-dependent kerma factors and subtracted the result from the total measured kerma. (author)