Ambient dose equivalent conversion factors for high energy neutrons based on the ICRP 60 recommendations

Calculations of the ambient dose equivalent conversion factors for neutron energies from 20 MeV to 5 GeV have been performed using the Monte Carlo high energy transport code HADRON. The kerma approximation extended to the high energy region was applied in the calculations. The results obtained are compared with the previous data for an infinite slab 30 cm thick as well as with the recent calculations for the ICRU sphere. The influence of the phantom shape and dimension is expected to be fairly unimportant for high energy radiations. The discrepancies in dose equivalent data are explained mainly by incorrect quality factors of secondary charged particles used in earlier calculations. Another conclusion is that the ambient dose equivalent H*(10) satisfies the requirement of conservativity for high energy radiations in practical cases of radiation fields outside shields.