Himit M, Itoh T, Endo S, Fujikawa K, Hoshi M
Atomic Energy Research Institute, Kinki University, Osaka.
J Radiat Res. 1996 Jun;37(2):97-106. doi: 10.1269/jrr.37.97.
Paired Fricke solutions, made up from light water or heavy water and 0.8N in H2SO4 and 1 mM in Fe(NH4)2(SO4)2 and NaCl, were calibrated with 60Co gamma rays and with mixed neutron and gamma radiation from a 252Cf source. Absorbance increases, AL and AH, in light- and heavy-water Fricke dosimeters, respectively, increased with fast-neutron and gamma-ray tissue doses, Dn (GY) and D gamma (GY), of the mixed radiation as follows: AL = 0.00178Dn + 0.00371D gamma; AH = 0.00121Dn + 0.00442 D gamma. G-values of 7.2 and 5.5 were obtained for 252Cf neutrons in light- and heavy-water Fricke dosimeters, respectively. When we applied the pair of equations to AL and AH values observed after exposure to mixed radiation in a nuclear reactor, resulting Dn and D gamma 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 gamma-ray dose ratio is unknown.
由轻水或重水与0.8N硫酸、1mM硫酸亚铁铵和氯化钠组成的成对弗里克溶液，用60Coγ射线以及来自252Cf源的混合中子和γ辐射进行校准。轻水和重水弗里克剂量计中的吸光度增加量，分别为AL和AH，随着混合辐射的快中子和γ射线组织剂量Dn（戈瑞）和Dγ（戈瑞）的增加而增加，具体如下：AL = 0.00178Dn + 0.00371Dγ；AH = 0.00121Dn + 0.00442Dγ。在轻水和重水弗里克剂量计中，252Cf中子的G值分别为7.2和5.5。当我们将这对方程应用于在核反应堆中暴露于混合辐射后观察到的AL和AH值时，所得的Dn和Dγ值与用成对电离室测量的剂量在10%以内相符。弗里克剂量计所需的剂量为5戈瑞或更高。相比之下，我们发现即使中子与γ射线剂量比未知，洋葱根中的微核产率也能以合理的准确度测量混合辐射场中约10厘戈瑞量级的中子成分。
