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Journal Articles

Using soils for accident dosimetry; A Preliminary study using optically stimulated luminescence from quartz

Fujita, Hiroki; Jain, M.*; Murray, A. S.*

Proceedings in Radiochemistry, 1(1), p.45 - 48, 2011/09

Single-aliquot regenerative OSL (SAR OSL) method was developed specifically for measuring background dose in natural quartz extracted from soils collected around Tokai-mura. The objective was to assess the potential of using soils for retrospective assessment of a radiation accident. The SAR data showed good reproducibility and dose recovery, and there were no evidence of fading of quartz signal based on the "delayed" dose recovery experiments. The dose of minimum detection limit (MDL) was 0.1 Gy. The background doses were generally the range of the MDL - few Gy, and no clear trend in dose depth profile was observed. An absence of clear trend might be indicative of ongoing soil activity resulting remixing of grains from the surface. From these results, we conclude that the SAR OSL dosimetry using natural quartz extracted from soil could evaluate accident dose.

Journal Articles

Utilisation of OSL from table salt in retrospective dosimetry

Fujita, Hiroki; Jain, M.*; Murray, A. S.*

Hoken Butsuri, 46(1), p.60 - 65, 2011/06

Common salt has been previously suggested for use in dose estimation in accident dosimetry. In this study the optically stimulated luminescence (OSL) and the thermoluminescence (TL) characteristics of Ajishio are studied. A comparison of OSL and TL signals allows identification of common source traps. The initial OSL signal contains a dominant thermally unstable component, which necessitates a prior heat treatment. Based on these luminescence characteristics, a single - aliquot regenerative - dose (SAR) protocol is developed and tested. Using this OSL SAR protocol with blue-LED stimulation, a known given dose was measured to within one standard error in 6 out of 10 samples of different Japanese commercial salts. A minimum detection limit of 15 mGy was estimated using the OSL protocol. It is concluded that the OSL from Japanese commercial salts could almost be used successfully to derive precise estimates of accident dose.

Journal Articles

Retrospective dosimetry using Japanese brick quartz; A Way forward despite an unstable fast decaying OSL signal

Fujita, Hiroki; Jain, M.*; Murray, A. S.*

Radiation Measurements, 46(6-7), p.565 - 572, 2011/06

 Times Cited Count:5 Percentile:59.38(Nuclear Science & Technology)

Quartz extracted from burnt bricks has been previously suggested for use in dose estimation in accident dosimetry. In this study the thermoluminescence (TL) and optically stimulated luminescence (OSL) characteristics of quartz extracted from a Japanese commercial red brick produced by Mishima - Renga - Seizoujyo Co. are studied. A comparison of TL and OSL signals allows identification of common source traps. It is observed that OSL from the Japanese brick quartz shows unusual thermal and optical decay characteristics. In particular, the initial OSL signal contains a dominant thermally unstable component, which necessitates a prior heat treatment. Based on these luminescence characteristics, a single - aliquot regenerative - dose (SAR) protocol is developed and tested. Using this OSL SAR protocol a minimum detection limit of $$sim$$ 65 mGy was estimated; this value is similar to that from violet TL dosimetry and similar to that obtained using electron spin resonance dosimetry. Finally, dose - depth profiles after irradiation using $$^{60}$$Co and $$^{137}$$Cs were measured on two different commercial brick types (Mishima - Renga - Seizoujyo Co. and Hase - Renga Co.). The dose - depth profiles obtained using these sources were distinguishable within experimental errors. It is concluded that OSL from Japanese brick quartz could be used successfully to derive precise estimates of accident dose, and, possibly, distinguish between sources of $$gamma$$ radiation in a nuclear accident.

Journal Articles

${it Ab initio}$ study of hydrogen hydrate clathrates for hydrogen storage within the ITBL environment

Sluiter, M. H. F.*; Belosludov, R. V.*; Jain, A.*; Belosludov, V. R.*; Adachi, Hitoshi*; Kawazoe, Yoshiyuki*; Higuchi, Kenji; Otani, Takayuki

Lecture Notes in Computer Science 2858, p.330 - 341, 2003/00

Recently, for the first time a hydrate clathrate was discovered with hydrogen. Aside from the great technological promise that is inherent in storing hydorogen at high density at modest pressures, there is great scientefic interest as this would constitute the first hydrate clathrate with multiple guest molecules per cage. The multiple cage occupancy is controversial, and reproducibility of the experiments has been questioned. Therefore in this study we try to illucidate the remarkable stability of the hydrogen hydrate clathrate, and determine the thermodynamically most favored cage occpancy using highly accrate ${it ab initio}$ computer simulations in a parameter survey. To carry out these extraordinary demanding computations a distributed ${it ab initio}$ code has been developed using the SuperSINET with the ITBL software as the top-layer.

Oral presentation

The Use of OSL from table salt in retrospective dosimetry

Fujita, Hiroki; Jain, M.*; Murray, A.*

no journal, , 

Common salt (NaCl) has previously been suggested for use in dose estimation in accident dosimetry. In this study, we investigated the optically stimulated luminescence (OSL) and violet thermoluminescence (VTL) characteristics of "Aji-Shio" (Ajinomoto), a Japanese commercial salt. A comparison of OSL and TL signals allowed identification of common source traps. A single-aliquot regenerative-dose (SAR) OSL protocol was modified and tested. The protocol worked very well for six types of salt, but not for four other types of salt. A minimum detection limit of 15 mGy was estimated using the OSL protocol; this is lower than the value obtained from other forms of OSL retrospective dosimetry and lower than that obtained using electron spin resonance (ESR) dosimetry. It was concluded that the OSL from Japanese commercial salt could be used successfully to derive precise estimates of accident dose.

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