[Reactor neutron activation analysis for aluminium in the presence of phosphorus and silicon. Contributions of 28Al activities from 31P(n, alpha) 28Al and 28Si(n, p) 28Al reactions].

Reactor neutron activation analysis for aluminium in samples containing phosphorus and silicon was studied. The experiments were performed by using neumatic tube of the Kyoto University Reactor (KUR). At first, the ratios of the 28Al activity produced from 27Al(n, gamma) 28Al reaction by thermal neutrons to that from 31P(n, alpha) 28Al reaction by fast neutrons, and to that from 28Si(n, p) 28Al reaction were measured by gamma-ray spectrometry. With a ratio of about 5 for the thermal to fast neutron flux of KUR, the ratio of the 28Al activity from aluminium to that from phosphorus was to be 812 +/- 7, and to that from silicon 282 +/- 3. Secondly, the contributions of 28Al activities from phosphorus and silicon and the determination limit of aluminium were calculated for various parameters, such as fast neutron flux, thermal to fast neutron flux ratio, amounts of phosphorus and silicon, etc. Thirdly, on the basis of these results, aluminium contents in spinal cords and brains of amyotrophic lateral sclerosis, Parkinsonism-dementia complex and control cases were determined.