中性子発生管による石炭中の珪素・アルミニウムの放射化分析

抄録

The nondestructive analytical method of silicon and aluminium, components of ash in coal, has been studied by application. of fast neutron reactions of 14Mev neutron, produced by the midget type neutron generator tube. The available neutron flux of the generator is about 1.2×10⁵n/cm²/sec for 14Mev neutron and 1×10⁴n/cm²/sec for thermal neutron.
The sample coal and two standard samples (pure aluminium and silicon) were irradiated close together in irradiation hole of moderator for 10min., each standard sample consists of 0.5g of aluminium or siliconpowder dispersed in 5g of benzoicacid. By this irradiation; appreciable amounts of²⁸Al and ²⁷Mg have been produced due to the reactions as²⁸Si (n.p) ²⁸Al, ²⁷Al (n.γ) ²⁸Al and ²⁷Al (n.p) ²⁷Mg. Then, gamma activities of samples have been measured with 100-channels Nal scintillation spectrometer.
The silicon and aluminium content in a given sample coal can be determined by the comparing the photo peak counts of ²⁸Al and ²⁷Mg of a given gamma ray from the sample coal with the photo peak counts of these nuclides from same gamma ray in the spectrum of the standard sample. The relation between them are caluculated by the following eqations:
C_A=C_SAχ+C_AAY
C_M=C_SMχ+C_AMY
where, C_A and C_M are net counts of ²⁸Al and ²⁷Mg photo peak of an irradiated coal sample, respectively. C_SA and C_SM are net counts of ²⁸Al and ²⁷Mg photo peak of unit weight of irradiated silicon, respectively.
C_AA and C_AM are net counts of Al and Mg photo peak of unit weight of irradiated aluminium, respectively.
The content of silicon and aluminium in the sample coal determined by this proposed method agreed close with the results given by original chemical analysis. According the experiment, analytical limit of sensitivity of this method can be evaluated as 4mg for silicon and 12mg for aluminium in net weight for a given sample under the following consideration: relative standard deviation of net counts of ²⁸Al and ²⁷Mg photo peak≤20%.