@article{oai:air.repo.nii.ac.jp:00001315,
 author = {緒方, 武幸 and 水田, 敏夫 and 石山, 大三 and 高田, 實彌 and OGATA, Takeyuki and MIZUTA, Toshio and ISHIYAMA, Daizo and TAKADA, Jitsuya},
 issue = {2},
 journal = {素材物性学雑誌},
 month = {Dec},
 note = {Tungsten content in granitic rocks is precisely determined by an instrumental neutron
activation analysis method (INAA) using several standard samples. Natural geostandard rocks
are GSJ geostandard of JG-l. JG-la, JG-2, JR-2 and JR-3, and artificial standard
materials of JR-2 with added scheelite powder and tungsten-doped quartz sand were employed for
the analysis. Each sample (lOOmg) was irradiated for short time (l min, 2 min and 3 min) at
thermal neutron flux 2.8 X 1013 nlcm' Is and for long time (60min) at thermal neutron flux 2.3 X
1013 n I cm2 I s. Gamma-ray spectrum of 187 W at 685.72 keY was used for the tungsten
analysis in geostandards. The 187W gamma-ray spectrum was not recognized for Na-rich JG-l
(W concentration = 1.5 ppm), while the gamma spectrum of that was recognized for JR-2 (1.8
ppm). SiN ratios of 187W for geostandards that irradiated for 3 min and after cooling for 6 day
were higher than those of another irradiation conditions. The analytical error of tungsten in
geostandards with the confidential limit of 95% was ± 4.7 ppm. This INAA with 3 min
irradiation is the most suitable method for the tungsten-bearing samples was successfully
applied to wide range of tungsten (i.e. low W concentration of non-mineralized granites to high W
concentration of mineralized granite and scheelite-bearing ore).},
 pages = {29--35},
 title = {中性子放射化分析法による鉱化および非鉱化の花崗岩中のタングステンの定量},
 volume = {15},
 year = {2002}
}