摘要：Paired Fricke solutions, made up from light water or heavy water and 0.8 N in H 2 SO 4 and 1m M in Fe(NH 4 ) 2 (SO 4 ) 2 and NaCl, were calibrated with 60 Co γ rays and with mixed neutron and γ radiation from a 252 Cf source. Absorbance increases, A L and A H , in light- and heavy-water Fricke dosimeters, respectively, increased with fast-neutron and γ-ray tissue doses, D n (Gy) and D γ (Gy), of the mixed radiation as follows: A L =0.00178 D n 0.00371 D γ ; A H =0.00121 D n 0.00442D D γ . G -values of 7.2 and 5.5 were obtained for 252 Cf neutrons in light- and heavy-water Fricke dosimeters, respectively. When we applied the pair of equations to A L and A H values observed after exposure to mixed radiation in a nuclear reactor, resulting D n and D γ values agreed within 10% to doses measured with paired ionization chambers. Doses required for Fricke dosimeters were 5 Gy or more. In contrast, we found that micronuclear yields in onion roots can measure the neutron component of mixed radiation fields at the order of 10 cGy with reasonable accuracy even if the neutron to γ-ray dose ratio is unknown.
关键词：Fricke dosimeters; heavy water; fast neutrons; G(Fe 3 ) value; onion roots
