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Journal Articles

Quasifree neutron knockout from $$^{54}$$Ca corroborates arising $$N=34$$ neutron magic number

Chen, S.*; Lee, J.*; Doornenbal, P.*; Obertelli, A.*; Barbieri, C.*; Chazono, Yoshiki*; Navr$'a$til, P.*; Ogata, Kazuyuki*; Otsuka, Takaharu*; Raimondi, F.*; et al.

Physical Review Letters, 123(14), p.142501_1 - 142501_7, 2019/10

 Times Cited Count:0 Percentile:100(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

First online multireflection time-of-flight mass measurements of isobar chains produced by fusion-evaporation reactions; Toward identification of superheavy elements via mass spectroscopy

Schury, P.*; Wada, Michiharu*; Ito, Yuta*; Kaji, Daiya*; Arai, Fumiya*; MacCormick, M.*; Murray, I.*; Haba, Hiromitsu*; Jeong, S.*; Kimura, Sota*; et al.

Physical Review C, 95(1), p.011305_1 - 011305_6, 2017/01

AA2016-0638.pdf:0.71MB

 Times Cited Count:13 Percentile:7.19(Physics, Nuclear)

Using a multireflection time-of-flight mass spectrograph located after a gas cell coupled with the gas-filled recoil ion separator GARIS-II, the masses of several $$alpha$$-decaying heavy nuclei were directly and precisely measured. The nuclei were produced via fusion-evaporation reactions and separated from projectilelike and targetlike particles using GARIS-II before being stopped in a helium-filled gas cell. Time-of-flight spectra for three isobar chains, $$^{204}$$Fr-$$^{204}$$Rn-$$^{204}$$At-$$^{204}$$Po, $$^{205}$$Fr- $$^{205}$$Rn-$$^{205}$$At-$$^{205}$$Po-$$^{205}$$Bi, and $$^{206}$$Fr-$$^{206}$$Rn-$$^{206}$$At, were observed. Precision atomic mass values were determined for $$^{204-206}$$Fr, $$^{204,205}$$Rn, and $$^{204,205}$$At. Identifications of $$^{205}$$Bi, $$^{204,205}$$Po, $$^{206}$$Rn, and $$^{206}$$At were made with N$$leq$$10 detected ions, representing the next step toward use of mass spectrometry to identify exceedingly low-yield species such as superheavy element ions.

Journal Articles

Testing the application of quartz and feldspar luminescence dating to MIS 5 Japanese marine deposits

Thiel, C.*; Tsukamoto, Sumiko*; Tokuyasu, Kayoko; Buylaert, J.-P.*; Murray, A. S.*; Tanaka, Kazuhiro*; Shirai, Masaaki*

Quaternary Geochronology, 29, p.16 - 29, 2015/08

 Times Cited Count:5 Percentile:65.78(Geography, Physical)

The applicability of both quartz and feldspar luminescence dating was tested on twenty-five samples from a marine succession now forming a cliff at Oga Peninsula, Honshu Island, Japan. The quartz shows thermal instability and linear modulated optically stimulated luminescence (LM-OSL) analysis revealed the dominance of a slow component. When compared with independent age control provided by two marker tephra, the quartz OSL ages grossly underestimated the depositional age. In contrast, potassium (K)-rich feldspar is a suitable dosimeter when measured using post-IR infrared stimulated luminescence (IRSL) at 225$$^{circ}$$C, but it was found that the fading corrected ages calculated using dose rates based on sieved grain-size still underestimate. SEM analyses on the feldspar extracts revealed that the grains are amorphous with small crystalline inclusions; using standard internal dose rate parameters, this would result in a too large dose rate. Three different dose rate scenarios were considered for calculation: (1) sieved grain size (90-180$$mu$$m) and 12.5$$pm$$0.5% K. (2) smaller grain size (40$$pm$$20$$mu$$m) and measured K concentration (6$$pm$$0.5%), and (3) smaller grain size consistent with the observed crystal dimensions (40$$pm$$20$$mu$$m) and 12.5$$pm$$0.5% K. The final dose rate scenario produces fading corrected ages that agree well with independent age control.

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.

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