Measurement of kerma factors for carbon and A-150 plastic: neutron energies from 13.9 to 20.0 MeV

Neutron fluence and neutron kerma were measured under similar conditions for quasi-monoenergetic neutron fields with energies ranging from 13.9 to 20.0 MeV, in steps of about 0.5 MeV. The combination of two techniques, the proton recoil telescope to determine the neutron fluence and low-pressure proportional counters made of carbon and A-150 plastic to determine the kerma, enabled the kerma factors to be measured for each material with uncertainties lower than 8.0%. The kerma factor for carbon increases from 19.3 pGy cm2 to 32.4 pGy cm2 and for A-150 plastic from 61.4 pGy cm2 to 76.0 pGy cm2 for neutron energies ranging from 13.9 to 20 MeV. For neutron energies above 18 MeV in particular, present kerma factors for carbon are 10 to 15% lower than other experimental data and the values calculated from evaluated nuclear data by Caswell et al, but are in closer agreement with the values derived from nuclear models.