Determination of the kerma factors in tissue-equivalent plastic, C, Mg, and Fe for 14.7-MeV neutrons.

Microdosimetric measurements were made with tissue-equivalent plastic (TEP), C-, Mg-, and Fe-walled proportional counters filled with propane-based tissue equivalent (TE) gas and Ar gas and irradiated with 14.7-MeV neutrons. A theoretical model was used for the analysis of energy deposition in spherical detectors. An effective average mass stopping-power ratio and a W correction were calculated to convert the gas ionization to the kerma in the wall material. The neutron fluence at the position of microdosimetric measurements was determined with an associated particle chamber mounted with surface barrier detectors. The experimental measurements along with the calculated correction factors yielded kerma factors of 0.660 X 10(-8) cGy cm2 for TEP, 0.219 X 10(-8) cGy cm2 for C, 0.122 X 10(-8) cGy cm2 for Mg, and 0.479 X 10(-9) cGy cm2 for Fe. The estimated uncertainties are 8.0% for TEP, 10.5% for C, and 9.3% for Mg and Fe.