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Journal Articles

Influence of linear energy transfer on the scintillation decay behavior in a lithium glass scintillator

Koshimizu, Masanori*; Iwamatsu, Kazuhiro*; Taguchi, Mitsumasa; Kurashima, Satoshi; Kimura, Atsushi; Yanagida, Takayuki*; Fujimoto, Yutaka*; Watanabe, Kenichi*; Asai, Keisuke*

Journal of Luminescence, 169(Part B), p.678 - 681, 2016/01

We analyzed the effects of linear energy transfer (LET) on the scintillation properties of a Li glass scintillator, GS20. The scintillation time profiles were measured by using pulsed ion beams having different LETs. The rise in the scintillation time profiles was faster for higher LET, whereas the decay part was not significantly different for largely different LETs. The LET effects in the rise was ascribed to the effects of excited states interaction during the energy transfer process from the host glass to the luminescent centers, Ce$$^{3+}$$ ions. Supposing that the light yield decreases with LET, the fast rise at high LET was explained in terms of the competition between the energy transfer and the quenching due to the excited states interaction.

Journal Articles

Linear energy transfer effects on time profiles of scintillation of Ce-doped LiCaAlF$$_{6}$$ crystals

Yanagida, Takayuki*; Koshimizu, Masanori*; Kurashima, Satoshi; Iwamatsu, Kazuhiro*; Kimura, Atsushi; Taguchi, Mitsumasa; Fujimoto, Yutaka*; Asai, Keisuke*

Nuclear Instruments and Methods in Physics Research B, 365(Part B), p.529 - 532, 2015/12

 Times Cited Count:9 Percentile:69.75(Instruments & Instrumentation)

We measured temporal profiles of scintillation of Ce-doped LiCaAlF$$_{6}$$ scintillator crystals at different linear energy transfers (LETs). Based on the comparison of the high-LET temporal profiles with those at low LET, we found that a fast component was observed only at low LET. The disappearance of the fast component at high LET is tentatively ascribed to quenching of excited states at defects owing to the interaction between excited states via Auger process. In addition, the rise and the initial decay behavior was dependent on the LET. This LET-dependent behavior is explained by a seeming acceleration process and a slowing down process in energy transfer at high LET. The LET-dependent temporal profiles provide a basis of discrimination technique of $$gamma$$-ray and neutron detection events using these scintillators based on the nuclear reaction, $$^{6}$$Li(n,$$alpha$$)t.

Journal Articles

System for measuring temporal profiles of scintillation at high and different linear energy transfers by using pulsed ion beams

Koshimizu, Masanori*; Kurashima, Satoshi; Taguchi, Mitsumasa; Iwamatsu, Kazuhiro; Kimura, Atsushi; Asai, Keisuke*

Review of Scientific Instruments, 86(1), p.013101_1 - 013101_5, 2015/01

 Times Cited Count:9 Percentile:47.26(Instruments & Instrumentation)

We have developed a system for measuring the temporal profiles of scintillation at high linear energy transfer (LET) by using pulsed ion beams from a cyclotron. The half width at half maximum time resolution was estimated to be 1.5-2.2 ns, which we attributed mainly to the duration of the pulsed ion beam and timing jitter between the trigger signal and the arrival of the ion pulse. The temporal profiles of scintillation of BaF$$_{2}$$ at different LETs were successfully observed. These results indicate that the proposed system is a powerful tool for analyzing the LET effects in temporal profiles of scintillation.

Journal Articles

Isotope dilution inductively coupled plasma mass spectrometry for determination of $$^{126}$$Sn content in spent nuclear fuel sample

Asai, Shiho; Toshimitsu, Masaaki; Hanzawa, Yukiko; Suzuki, Hideya; Shinohara, Nobuo; Inagawa, Jun; Okumura, Keisuke; Hotoku, Shinobu; Kimura, Takaumi; Suzuki, Kensuke*; et al.

Journal of Nuclear Science and Technology, 50(6), p.556 - 562, 2013/06

 Times Cited Count:8 Percentile:59.34(Nuclear Science & Technology)

The $$^{126}$$Sn content in a spent nuclear fuel solution was determined by ICP-MS for its inventory estimation in high-level radioactive waste. An irradiated UO$$_{2}$$ fuel was used as a sample to evaluate the reliability of the methodology. Prior to the measurement, Sn was separated from $$^{126}$$Te, which causes major isobaric interference in the determination of $$^{126}$$Sn content, along with highly radioactive coexisting elements using an anion-exchange column. The absence of counts attributed to Te in the Sn-containing effluent indicates that Te was completely removed. After washing, Sn retained on the column was readily eluted with 1 M HNO$$_{3}$$. The isotope ratios of Sn were successfully determined and showed good agreement with those obtained through ORIGEN2 calculations. The results reported in this paper are the first experimental values of $$^{126}$$Sn content in the spent nuclear fuel solution originating in spent nuclear fuel irradiated at a nuclear power plant in Japan.

Journal Articles

Sulfate complexation of element 104, Rf, in H$$_{2}$$SO$$_{4}$$/HNO$$_{3}$$ mixed solution

Li, Z.*; Toyoshima, Atsushi; Asai, Masato; Tsukada, Kazuaki; Sato, Tetsuya; Sato, Nozomi; Kikuchi, Takahiro; Nagame, Yuichiro; Sch$"a$del, M.; Pershina, V.*; et al.

Radiochimica Acta, 100(3), p.157 - 164, 2012/03

 Times Cited Count:10 Percentile:65.97(Chemistry, Inorganic & Nuclear)

Journal Articles

X-ray detection capability of a BaCl$$_{2}$$ single crystal scintillator

Koshimizu, Masanori*; Onodera, Kazuya*; Nishikido, Fumihiko*; Haruki, Rie; Shibuya, Kengo*; Kishimoto, Shunji*; Asai, Keisuke*

Journal of Applied Physics, 111(2), p.024906_1 - 024906_5, 2012/01

 Times Cited Count:22 Percentile:70.04(Physics, Applied)

Journal Articles

Simple cation-exchange separation for ICP-MS measurement of $$^{79}$$Se in spent nuclear fuel sample

Asai, Shiho; Hanzawa, Yukiko; Suzuki, Hideya; Toshimitsu, Masaaki; Okumura, Keisuke; Shinohara, Nobuo; Kimura, Takaumi; Inagawa, Jun; Suzuki, Kensuke*; Kaneko, Satoru*

Proceedings of International Conference on Toward and Over the Fukushima Daiichi Accident (GLOBAL 2011) (CD-ROM), 5 Pages, 2011/12

Journal Articles

New ORIGEN2 libraries based on JENDL-4.0 and their validation for long-lived fission products by post irradiation examination analyses of LWR spent fuels

Kojima, Kensuke; Okumura, Keisuke; Asai, Shiho; Hanzawa, Yukiko; Okamoto, Tsutomu; Toshimitsu, Masaaki; Inagawa, Jun; Kimura, Takaumi; Kaneko, Satoru*; Suzuki, Kensuke*

Proceedings of International Conference on Toward and Over the Fukushima Daiichi Accident (GLOBAL 2011) (CD-ROM), 5 Pages, 2011/12

Accurate inventory estimation of long-lived fission products (LLFPs) in LWR spent fuels is important for the quality management and for long-term safety assessment of high-level radioactive vitrified wastes. In Japan, ORIGEN2 has been widely used to estimate the fuel compositions. However, equipped library data in the original ORIGEN2 are old and are not validated enough for LLFPs, such as $$^{79}$$Se, $$^{99}$$Tc, $$^{126}$$Sn and $$^{135}$$Cs, because available post irradiation examination (PIE) data are limited for these nuclides, which have difficulties in radiochemical analyses. For more accurate the estimation, new ORIGEN2 libraries are developed from the latest nuclear data library JENDL-4.0 for cross sections and fission yields, and from other libraries for half-lives, and so on. The new libraries are validated by PIE analyses of the sample fuels irradiated in Cooper, Calvert-Cliffs-1, H. B. Robinson-2, and Ohi-1. As a result, it was found that the new library gives good results for the estimation.

Journal Articles

Analyses of assay data of LWR spent nuclear fuels with a continuous-energy Monte Carlo code MVP and JENDL-4.0 for inventory estimation of $$^{79}$$Se, $$^{99}$$Tc, $$^{126}$$Sn and $$^{135}$$Cs

Okumura, Keisuke; Asai, Shiho; Hanzawa, Yukiko; Suzuki, Hideya; Toshimitsu, Masaaki; Inagawa, Jun; Okamoto, Tsutomu; Shinohara, Nobuo; Kaneko, Satoru*; Suzuki, Kensuke*

Progress in Nuclear Science and Technology (Internet), 2, p.369 - 374, 2011/10

For accurate inventory estimation of long-lived fission products in LWR spent fuels, a new burn-up chain model and decay data based on the latest nuclear data such as JENDL-4.0 was developed. MVP-BURN with the latest nuclear data was applied to several post irradiation examinations including inventory measurements of $$^{79}$$Se, $$^{99}$$Tc, $$^{126}$$Sn and $$^{135}$$Cs. One of them is a new measurement by JAEA. From the PIE analyses, it is found that the new PIE data obtained by JAEA is consistent with the other PIE data by different laboratory with different techniques. It is also confirmed that the present calculation results show good agreements with experimental ones within about 10% for productions of $$^{79}$$Se and $$^{135}$$Cs. In contrast, amounts of $$^{99}$$Tc and $$^{126}$$Sn are overestimated by about 50%. These discrepancies are likely due to the effect of insoluble residue produced during sample dissolution and/or errors of fission yields in the analyses.

Journal Articles

Validation of correlations between Nd isotopes and difficult-to-measure nuclides predicted with burn-up calculation code by post irradiation examination

Asai, Shiho; Okumura, Keisuke; Hanzawa, Yukiko; Suzuki, Hideya; Toshimitsu, Masaaki; Inagawa, Jun; Kimura, Takaumi; Kaneko, Satoru*; Suzuki, Kensuke*

Proceedings of 14th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM 2011) (CD-ROM), p.1437 - 1442, 2011/09

Journal Articles

Computational study for inventory estimation of Se-79, Tc-99, Sn-126, and Cs-135 in high-level radioactive wastes from spent nuclear fuels of light water reactors

Okumura, Keisuke; Asai, Shiho; Hanzawa, Yukiko; Okamoto, Tsutomu; Suzuki, Hideya; Toshimitsu, Masaaki; Inagawa, Jun; Kimura, Takaumi; Suzuki, Kensuke*; Kaneko, Satoru*

Proceedings of 14th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM 2011) (CD-ROM), p.1443 - 1450, 2011/09

Inventory estimation of long-lived fission products (LLFPs) in high-level radioactive wastes (HLW) from spent nuclear fuels of light water reactors is important for a safety assessment of their disposal. In order to develop an inventory estimation method of difficult-to-measure LLFPs (Se-79, Tc-99, Sn-126, and Cs-135), a parametric study was carried out by using a sophisticated burnup calculation code and data. In the parametric study, fuel specifications and irradiation conditions are changed in the conceivable range. The considered parameters are fuel assembly types (PWR / BWR), U-235 enrichment, moderator temperature, void fraction, power density, and so on. From the calculated results, we clarify the burnup characteristics of the target LLFPs and their possible ranges of generations. Finally, candidates of the key nuclide are proposed for the scaling factor method of HLW.

Journal Articles

Optimization of ion-beam irradiation for mutagenesis in soybean; Effects on plant growth and production of visibly altered mutants

Arase, Sachiko*; Hase, Yoshihiro; Abe, Jun*; Kasai, Megumi*; Yamada, Tetsuya*; Kitamura, Keisuke*; Narumi, Issei; Tanaka, Atsushi; Kanazawa, Akira*

Plant Biotechnology, 28(3), p.323 - 329, 2011/06

 Times Cited Count:17 Percentile:54.04(Biotechnology & Applied Microbiology)

Journal Articles

Determination of $$^{79}$$Se and $$^{135}$$Cs in spent nuclear fuel for inventory estimation of high-level radioactive wastes

Asai, Shiho; Hanzawa, Yukiko; Okumura, Keisuke; Shinohara, Nobuo; Inagawa, Jun; Hotoku, Shinobu; Suzuki, Kensuke*; Kaneko, Satoru*

Journal of Nuclear Science and Technology, 48(5), p.851 - 854, 2011/05

 Times Cited Count:23 Percentile:88.07(Nuclear Science & Technology)

Journal Articles

Neutron one-quasiparticle states in $$^{251}$$Fm$$_{151}$$ populated via the $$alpha$$ decay of $$^{255}$$No

Asai, Masato; Tsukada, Kazuaki; Haba, Hiromitsu*; Ishii, Yasuo; Ichikawa, Takatoshi*; Toyoshima, Atsushi; Ishii, Tetsuro; Nagame, Yuichiro; Nishinaka, Ichiro; Kojima, Yasuaki*; et al.

Physical Review C, 83(1), p.014315_1 - 014315_12, 2011/01

 Times Cited Count:19 Percentile:76.34(Physics, Nuclear)

Excited states in $$^{251}$$Fm populated via the $$alpha$$ decay of $$^{255}$$No are studied in detail through $$alpha$$-$$gamma$$ coincidence and $$alpha$$ fine structure measurements. Spin-parities and neutron configurations of the excited states in $$^{251}$$Fm as well as the ground state of $$^{255}$$No are definitely identified on the basis of deduced internal conversion coefficients, lifetimes of $$gamma$$ transitions, rotational-band energies built on one-quasiparticle states, and hindrance factors of $$alpha$$ transitions. It is found that the excitation energy of the 1/2$$^{+}$$[620] state in $$N$$=151 isotones increases with the atomic number, especially at $$Z$$$$ge$$100, while that of the 1/2$$^{+}$$[631] state decreases at $$Z$$=100. Energy systematics of the one-quasiparticle states in the $$N$$=151 isotones are discussed in terms of the evolution of nuclear deformation involving the hexadecapole and hexacontatetrapole deformations.

Journal Articles

Comparison of post-irradiation experimental data and theoretical calculations for inventory estimation of long-lived fission products in spent nuclear fuel

Asai, Shiho; Hanzawa, Yukiko; Okumura, Keisuke; Suzuki, Hideya; Toshimitsu, Masaaki; Shinohara, Nobuo; Kaneko, Satoru*; Suzuki, Kensuke*

Proceedings of 13th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM 2010) (CD-ROM), p.261 - 264, 2010/10

Journal Articles

Post irradiation examination analyses with a continuous-energy Monte Carlo code MVP for long-lived fission products in LWR spent fuels

Okumura, Keisuke; Asai, Shiho; Hanzawa, Yukiko; Suzuki, Hideya; Toshimitsu, Masaaki; Inagawa, Jun; Katakura, Junichi; Shinohara, Nobuo; Kaneko, Satoru*; Suzuki, Kensuke*

Proceedings of Joint International Conference of 7th Supercomputing in Nuclear Application and 3rd Monte Carlo (SNA + MC 2010) (USB Flash Drive), 5 Pages, 2010/10

For accurate inventory estimation of long-lived fission products in LWR spent fuels, a new burn-up chain model and decay data based on the latest nuclear data were developed for MVP-BURN. They were applied to three post irradiation examinations including inventory measurements of $$^{79}$$Se, $$^{99}$$Tc, $$^{126}$$Sn and $$^{135}$$Cs. One of them is new measurements performed by JAEA. From the PIE analyses, it is found that the new measurements by JAEA are consistent with the other PIE data obtained by different laboratory with different techniques. It is also confirmed that the present calculation results show good agreements with experimental ones for $$^{79}$$Se and $$^{135}$$Cs within about 10%. In contrast, amounts of $$^{99}$$Tc and $$^{126}$$Sn are overestimated by about up to 50%. These discrepancies are likely due to the effect of insoluble residue in the measurements and/or errors of fission yields in the analyses.

Journal Articles

Extraction of chromatographic behavior of Rf, Zr, and Hf in HCl solution with styrenedivinylbenzene copolymer resin modified by TOPO (trioctylphosphine oxide)

Toyoshima, Atsushi; Kasamatsu, Yoshitaka*; Tsukada, Kazuaki; Asai, Masato; Ishii, Yasuo; Tome, Hayato*; Nishinaka, Ichiro; Sato, Tetsuya; Nagame, Yuichiro; Sch$"a$del, M.; et al.

Journal of Nuclear and Radiochemical Sciences, 11(1), p.7 - 11, 2010/06

The extraction behavior of rutherfordium (Rf) into trioctylphosphine oxide (TOPO) from 2.0 - 7.0 M HCl solution was studied together with that of the homologues Zr and Hf. The extracted yields of Rf, Zr, and Hf increased with an increase of HCl concentration, and the sequence of their extraction was Zr $$>$$ Hf $$geq$$ Rf. It is suggested that the stability of the RfCl$$_{4}$$$$cdot$$2(TOPO) complex is lower than that of the corresponding species of the homologues.

Journal Articles

$$^{225}$$Ac metallofullerene; Toward $$^{225}$$Ac nanogenerator in fullerene

Akiyama, Kazuhiko*; Haba, Hiromitsu*; Sueki, Keisuke*; Tsukada, Kazuaki; Asai, Masato; Toyoshima, Atsushi; Nagame, Yuichiro; Katada, Motomi*

Chemistry Letters, 38(10), p.978 - 979, 2009/09

 Times Cited Count:9 Percentile:39.61(Chemistry, Multidisciplinary)

We report on the successful production of a metallofullerene encapsulating the radioactive tracer $$^{225}$$Ac and on its electronic properties studied by radiochromatography. Considering the number of $$pi$$-electrons on the fullerene cage estimated from an HPLC retention time on the 5PBB column and the general oxidation state of Ac (+3), a chemical species of the dominant chromatographic peak is suggested to be Ac@C$$_{82}$$.

Journal Articles

Chloride complexation of Zr and Hf in HCl investigated by extended X-ray absorption fine structure spectroscopy; Toward characterization of chloride complexation of element 104, rutherfordium (Rf)

Haba, Hiromitsu*; Akiyama, Kazuhiko*; Tsukada, Kazuaki; Asai, Masato; Toyoshima, Atsushi; Yaita, Tsuyoshi; Hirata, Masaru; Sueki, Keisuke*; Nagame, Yuichiro

Bulletin of the Chemical Society of Japan, 82(6), p.698 - 703, 2009/06

 Times Cited Count:10 Percentile:41.76(Chemistry, Multidisciplinary)

Chloride complexation of the group-4 elements Zr and Hf in 8.0-11.9 M HCl is investigated by Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy to characterize chloro complexes of the transactinide element, rutherfordium (Rf). The complexes of Zr and Hf successively vary with the concentration of HCl from a hydrated complex [M(H$$_{2}$$O) $$_{8}$$]$$^{4+}$$ at 8.0 M to a hexachloro complex [MCl$$_{6}$$]$$^{2-}$$ at 11.9 M (M = Zr and Hf). The present structural changes of the Zr and Hf complexes well reflect the previously studied anion-exchange behavior of Zr and Hf in HCl. From both the EXAFS and anion-exchange results, we suggest that Rf forms the same complexes as those of Zr and Hf in HCl, and that the complexation strength of the hexachloro complexes of the group-4 elements, [MCl$$_{6}$$] $$^{2-}$$ (M = Zr, Hf, and Rf), is in the sequence of Rf $$>$$ Zr $$>$$ Hf.

Journal Articles

A Metallofullerene that encapsulates $$^{225}$$Ac

Akiyama, Kazuhiko*; Haba, Hiromitsu*; Tsukada, Kazuaki; Asai, Masato; Toyoshima, Atsushi; Sueki, Keisuke*; Nagame, Yuichiro; Katada, Motomi*

Journal of Radioanalytical and Nuclear Chemistry, 280(2), p.329 - 331, 2009/05

 Times Cited Count:7 Percentile:48.67(Chemistry, Analytical)

The properties of a metallofullerene that encapsulates $$^{225}$$Ac were studied by radio-chromatographic methods. The results of chromatography on a Buckyclutcher column suggest that there are some metallofullerene isomers of AcC$$_{82}$$. The identical HPLC retention time of the major AcC$$_{82}$$ peak with that of La@C$$_{82}$$ indicates that the structure of one of the AcC$$_{82}$$ isomers is the same as La@C$$_{82}$$.

103 (Records 1-20 displayed on this page)