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100 MeV/nucleonPohl, T.*; Sun, Y. L.*; Obertelli, A.*; Lee, J.*; G
mez-Ramos, M.*; Ogata, Kazuyuki*; Yoshida, Kazuki; Cai, B. S.*; Yuan, C. X.*; Brown, B. A.*; et al.
Physical Review Letters, 130(17), p.172501_1 - 172501_8, 2023/04
We report on the first proton-induced single proton- and neutron-removal reactions from the neutron deficient 
O nucleus with large Fermi-surface asymmetry at 100 MeV/nucleon. Our results provide the first quantitative contributions of multiple reaction mechanisms including the quasifree knockout, inelastic scattering, and nucleon transfer processes. It is shown that the inelastic scattering and nucleon transfer, usually neglected at such energy regime, contribute about 50% and 30% to the loosely bound proton and deeply bound neutron removal, respectively.
Sr and 
Cs by AMSHonda, Maki; Martschini, M.*; Wieser, A.*; Marchhart, O.*; Lachner, J.*; Priller, A.*; Steier, P.*; Golser, R.*; Sakaguchi, Aya*
JAEA-Conf 2022-001, p.85 - 90, 2022/11
Accelerator mass spectrometry (AMS) is an analytical method that combines mass spectrometry with a tandem accelerator, which has been used mainly in nuclear physics experiments. AMS is used to measure radionuclides with half-lives of 10
-10
years. For radionuclides with half-lives of this order, the method of measuring their mass is 10-10
times more sensitive than measuring their activity. Because of this advantage, AMS has been widely applied in Earth and planetary sciences, atomic energy research, and other fields. Among the various studies, Wallner et al. (2021, 2016) have achieved excellent work in Earth and planetary sciences. For example, they have attained the ultra-sensitive analysis of 
Fe and 
Pu in environmental samples. These are radionuclides produced by rapid-neutron-capture (r-process) nucleosynthesis. Our recent work shows that a new AMS system (VERA, University of Vienna), which combines laser isobaric separation and a typical AMS system, has been successfully applied to the ultra-sensitive determination of Sr and Cs in environment. For Sr in environmental samples, the 
-ray measurement by the milking of the daughter nuclide Y is still the principal method, which takes 3-6 weeks. The new AMS method has a detection limit of 
0.1 mBq, which is comparable to that of -ray measurement, with a more straightforward chemical treatment than -measurement. Our achievement demonstrates that AMS can be a practical new method for determining Sr in the environment.
Sr analysis of environmental samples by ion-laser interaction mass spectrometryHonda, Maki; Martschini, M.*; Marchhart, O.*; Priller, A.*; Steier, P.*; Golser, R.*; Sato, Tetsuya; Tsukada, Kazuaki; Sakaguchi, Aya*
Analytical Methods, 14(28), p.2732 - 2738, 2022/07
Times Cited Count：2 Percentile：76.85(Chemistry, Analytical)The sensitive Sr analysis with accelerator mass spectrometry (AMS) was developed for the advances of environmental radiology. One advantage of AMS is the ability to analyze various environmental samples with Sr/
Sr atomic ratios of 10
in a simple chemical separation. Three different IAEA samples with known Sr concentrations (moss-soil, animal bone, Syrian soil: 1 g each) were analyzed to assess the validity of the chemical separation and the AMS measurement. The Sr measurements were conducted on the AMS system combined with the Ion Laser InterAction MasSpectrometry (ILIAMS) setup at the University of Vienna, which has excellent isobaric separation performance. The isobaric interference of Zr in the Sr AMS was first removed by chemical separation. The separation factor of Zr in two-step column chromatography with Sr resin and anion exchange resin was 10. The Zr remaining in the sample was removed by ILIAMS effectively. This simple chemical separation achieved a limit of detection 0.1 mBq in the Sr AMS, which is lower than typical -ray detection. The agreement between AMS measurements and nominal values for the Sr concentrations of IAEA samples indicated that the new highly-sensitive Sr analysis in the environmental samples with AMS is reliable even for high matrix samples of soil and bone.
Hain, K.*; Martschini, M.*; G
lce, F.*; Honda, Maki; Lachner, J.*; Kern, M.*; Pitters, J.*; Quinto, F.*; Sakaguchi, Aya*; Steier, P.*; et al.
Frontiers in Marine Science (Internet), 9, p.837515_1 - 837515_17, 2022/03
Times Cited Count：7 Percentile：97.47(Environmental Sciences)Recent major advances in accelerator mass spectrometry (AMS) at the Vienna Environmental Research Accelerator (VERA) regarding detection efficiency and isobar suppression have opened possibilities for the analysis of additional long-lived radionuclides at ultra-low environmental concentrations. These radionuclides, including 
U, Cs, 
Tc and Sr, will become important for oceanographic tracer application due to their generally conservative behavior in ocean water. In particular, the isotope ratios U/
U and 
Cs/Cs have proven to be powerful fingerprints for emission source identification as they are not affected by elemental fractionation. Improved detection efficiencies allowed us to analyze all major long-lived actinides, i.e. U, 
Np, 
Pu, 
Am as well as the very rare U, in the same 10 L water samples of an exemplary depth profile from the northwest Pacific Ocean. Especially for Sr analysis, our new approach has already been validated for selected reference materials (e.g. IAEA-A-12) and is ready for application in oceanographic studies. We estimate that a sample volume of only (1-3) L ocean water is sufficient for Sr as well as Cs analysis, respectively.
Miura, Hikaru*; Ishimaru, Takashi*; Ito, Yukari*; Kuribara, Yuichi; Otosaka, Shigeyoshi*; Sakaguchi, Aya*; Misumi, Kazuhiro*; Tsumune, Daisuke*; Kubo, Atsushi*; Higaki, Shogo*; et al.
Scientific Reports (Internet), 11, p.5664_1 - 5664_11, 2021/03
Times Cited Count：8 Percentile：64.15(Multidisciplinary Sciences)For the first time, we isolated and investigated seven CsMPs (radioactive caesium-bearing microparticles) from marine particulate matter and sediment. From the elemental composition, the 
Cs/Cs activity ratio, and the Cs activity per unit volume results, we inferred that the five CsMPs collected from particulate matter were emitted from Unit 2 of the FDNPP, whereas the two CsMPs collected from marine sediment were possibly emitted from Unit 3. The presence of CsMPs can cause overestimation of the solid-water distribution coefficient of Cs in marine sediments and particulate matter and a high apparent radiocaesium concentration factor for marine biota. CsMPs emitted from Unit 2, which were collected from the estuary of a river that flowed through a highly contaminated area, may have been deposited on land and then transported by the river. By contrast, CsMPs emitted from Unit 3 were possibly transported eastward by the wind and deposited directly onto the ocean surface.
-Orbital component in the Borromean nucleus 
BYang, Z. H.*; Kubota, Yuki*; Corsi, A.*; Yoshida, Kazuki; Sun, X.-X.*; Li, J. G.*; Kimura, Masaaki*; Michel, N.*; Ogata, Kazuyuki*; Yuan, C. X.*; et al.
Physical Review Letters, 126(8), p.082501_1 - 082501_8, 2021/02
Times Cited Count：29 Percentile：96.61(Physics, Multidisciplinary)A quasifree (
,
) experiment was performed to study the structure of the Borromean nucleus B, which had long been considered to have a neutron halo. By analyzing the momentum distributions and exclusive cross sections, we obtained the spectroscopic factors for 
and 
orbitals, and a surprisingly small percentage of 9(2)% was determined for . Our finding of such a small component and the halo features reported in prior experiments can be explained by the deformed relativistic Hartree-Bogoliubov theory in continuum, revealing a definite but not dominant neutron halo in B. The present work gives the smallest - or -orbital component among known nuclei exhibiting halo features and implies that the dominant occupation of or orbitals is not a prerequisite for the occurrence of a neutron halo.
Sasa, Kimikazu*; Honda, Maki; Hosoya, Seiji*; Takahashi, Tsutomu*; Takano, Kenta*; Ochiai, Yuta*; Sakaguchi, Aya*; Kurita, Saori*; Satou, Yukihiko; Sueki, Keisuke*
Journal of Nuclear Science and Technology, 58(1), p.72 - 79, 2021/01
Times Cited Count：8 Percentile：80.25(Nuclear Science & Technology)Miura, Hikaru*; Kuribara, Yuichi; Yamamoto, Masayoshi*; Sakaguchi, Aya*; Yamaguchi, Noriko*; Sekizawa, Oki*; Nitta, Kiyofumi*; Higaki, Shogo*; Tsumune, Daisuke*; Itai, Takaaki*; et al.
Scientific Reports (Internet), 10, p.11421_1 - 11421_9, 2020/07
Times Cited Count：14 Percentile：69.92(Multidisciplinary Sciences)
F from 
O
?Tang, T. L.*; Uesaka, Tomohiro*; Kawase, Shoichiro; Beaumel, D.*; Dozono, Masanori*; Fujii, Toshihiko*; Fukuda, Naoki*; Fukunaga, Taku*; Galindo-Uribarri, A.*; Hwang, S. H.*; et al.
Physical Review Letters, 124(21), p.212502_1 - 212502_6, 2020/05
Times Cited Count：13 Percentile：78.47(Physics, Multidisciplinary)The structure of a neutron-rich F nucleus is investigated by a quasifree (
) knockout reaction. The sum of spectroscopic factors of 
orbital is found to be 1.0 
0.3. The result shows that the O core of F nucleus significantly differs from a free O nucleus, and the core consists of 35% O
, and 65% excited O. The result shows that the O core of F nucleus significantly differs from a free O nucleus. The result may infer that the addition of the proton considerably changes the neutron structure in F from that in O, which could be a possible mechanism responsible for the oxygen dripline anomaly.
Kurihara, Momo*; Yasutaka, Tetsuo*; Aono, Tatsuo*; Ashikawa, Nobuo*; Ebina, Hiroyuki*; Iijima, Takeshi*; Ishimaru, Kei*; Kanai, Ramon*; Karube, Jinichi*; Konnai, Yae*; et al.
Journal of Radioanalytical and Nuclear Chemistry, 322(2), p.477 - 485, 2019/11
Times Cited Count：2 Percentile：25.74(Chemistry, Analytical)We assessed the repeatability and reproducibility of methods for determining low dissolved radiocesium concentrations in freshwater in Fukushima. Twenty-one laboratories pre-concentrated three of 10 L samples by five different pre-concentration methods (prussian-blue-impregnated filter cartridges, coprecipitation with ammonium phosphomolybdate, evaporation, solid-phase extraction disks, and ion-exchange resin columns), and activity of radiocesium was measured. The z-scores for all of the Cs results were within 2, indicating that the methods were accurate. The relative standard deviations (RSDs) indicating the variability in the results from different laboratories were larger than the RSDs indicating the variability in the results from each separate laboratory.
Kawakita, Yukinobu; Kikuchi, Tatsuya*; Inamura, Yasuhiro; Tahara, Shuta*; Maruyama, Kenji*; Hanashima, Takayasu*; Nakamura, Mitsutaka; Kiyanagi, Ryoji; Yamauchi, Yasuhiro*; Chiba, Kaori*; et al.
Physica B; Condensed Matter, 551, p.291 - 296, 2018/12
Times Cited Count：9 Percentile：45.99(Physics, Condensed Matter)There are elemental liquid metals with complex structures far from the hard sphere (HS) packing model. Liquid Bi has an asymmetric first peak in the structure factors S(Q). The pair distribution function g(r) exhibits strange distance ratio of 1:2 between the first and the second peaks. Since a HS model with two kinds of radius produces asymmetry of the main peak in S(Q), existence of short-lived covalent bonds was discussed. Contrarily, modulation of the atomic distribution by the Friedel oscillations of shielding electrons around metallic ions was discussed. To examine its bonding nature from viewpoints of dynamic correlation functions, we have measured neutron quasielastic scattering of liquid Bi by using cold disk chopper spectrometer installed at MLF of J-PARC. The van Hove function revealed that the shoulder structure located at a longer side of the first peak in g(r) exhibits a longer relaxation time than the main structures such as the first and second peaks.
S
films; Case of pre-reactionSakaguchi, Yoshifumi*; Hanashima, Takayasu*; Aoki, Hiroyuki; Asaoka, Hidehito; Simon, A.-A. A.*; Mitkova, M.*
Physica Status Solidi (A), 215(12), p.1800049_1 - 1800049_12, 2018/06
Times Cited Count：5 Percentile：28.94(Materials Science, Multidisciplinary)Tanaka, Kazuya; Watanabe, Naoko*; Yamasaki, Shinya*; Sakaguchi, Aya*; Fan, Q.*; Takahashi, Yoshio*
Geochemical Journal, 52(2), p.173 - 185, 2018/00
Times Cited Count：9 Percentile：48.43(Geochemistry & Geophysics)We analyzed riverbed sediments collected at two sites, Yamakiya and Kuroiwa, in Fukushima after the Fukushima accident. The size distributions of K, Rb, and 
Csreflected the mineralogy of sediments, where primary host minerals for these alkali elements would be biotite, K-feldspar, and clay minerals. Silt-size fractions contained high Cs and Cs concentrations possibly due to adsorption on clay minerals. Their concentrations decreased with particle size at the Yamakiya site. In contrast, coarse and very coarse sand fractions from the Kuroiwa site showed higher Cs and Cs concentrations in comparison to fine - medium sand fractions. The coarse sand fractions contained many weathered biotite grains. Overall, the size distributions of Cs and Cs were similar in the sediments, suggesting that the Fukushima-derived radiocesium was distributed into each particle size fraction in response to the distribution of the stable Cs that was controlled by mineralogical composition.
Sakaguchi, Aya*; Chiga, Haruka*; Tanaka, Kazuya; Tsuruta, Haruo*; Takahashi, Yoshio*
Geochemical Journal, 52(2), p.187 - 199, 2018/00
Times Cited Count：7 Percentile：40.1(Geochemistry & Geophysics)An aerosol sample collected on the 15th of March 2011 at Kawasaki City (Kanagawa) was sequentially leached with seawater for 30 days. As a result, about 60% of the total Cs was extracted. In addition, a surface soil sample collected from Kawamata Town (Fukushima) two months after the Fukushima accident, was leached for 223 days with a natural seawater, a 1:1 mixture of ultrapure water and seawater, and ultrapure water. Eventually, more than 15% of the total Cs in the surface soil sample was efficiently desorbed by seawater leaching. In comparison, about 9% of the total Cs was leached with 1:1 diluted seawater and less than 1% of the total Cs was leached with ultrapure water over the 223 days. Overall, Cs and Cs showed similar leaching behaviour.
) of radiocesium in the Kuchibuto River in FukushimaMiura, Hikaru*; Kurihara, Yuichi*; Sakaguchi, Aya*; Tanaka, Kazuya; Yamaguchi, Noriko*; Higaki, Shogo*; Takahashi, Yoshio*
Geochemical Journal, 52(2), p.145 - 154, 2018/00
Times Cited Count：43 Percentile：94.32(Geochemistry & Geophysics)Solid-water distribution coefficient () of radiocesium in rivers is apparently increased due to the possible presence of highly radioactive radiocesium-bearing microparticles (CsMPs) in the solid phase. In this study, we evaluated the contribution of CsMPs to apparent Kd values. The ratio of the radioactivity of the separated CsMPs to the total radiocesium on fluvial suspended particles ranged from 0 to 46%. This means that the existence of CsMPs in fluvial suspended partcles did not change apparent Kd values in order magnitude.
Takahashi, Yoshio*; Fan, Q.*; Suga, Hiroki*; Tanaka, Kazuya; Sakaguchi, Aya*; Takeichi, Yasuo*; Ono, Kanta*; Mase, Kazuhiko*; Kato, Kenji*; Kanivets, V. V.*
Scientific Reports (Internet), 7(1), p.12407_1 - 12407_11, 2017/09
Times Cited Count：26 Percentile：68.78(Multidisciplinary Sciences)We focused on factors controlling partition of radiocesium on particulate matters and sediments in rivers of Fukushima and Chernobyl. Radiocesium is more soluble in the Pripyat River (Chernobyl) due to weaker interaction of radiocesium with clay minerals caused by the inhibition effect of the adsorbed humic substances. In contrast, particulate matters and sediments in the Kuchibuto River (Fukushima) display high adsorption affinity with lesser inhibition effect of adsorbed humic substances. This difference is possibly governed by the geology and soil type of provenances surrounding both catchments.
Iimoto, Takeshi*; Kinoshita, Norikazu*; Sakaguchi, Aya*; Sugihara, Shinji*; Takamiya, Koichi*; Tagami, Keiko*; Nagao, Seiya*; Bessho, Kotaro*; Matsumura, Hiroshi*; Miura, Taichi*; et al.
KEK Report 2016-3, 134 Pages, 2017/03
This report is summary of study on environmental radioactivity effected from the accident at the TEPCO Fukushima Daiichi Nuclear Power Plant in 5 years after the accident. It was compiled efforts related to the accident reported from the 13th to the 17th "Workshop on Environmental Radioactivity" which was held at the High Energy Accelerator Research and Development Organization.
Tanaka, Kazuya; Kondo, Hiroaki*; Sakaguchi, Aya*; Takahashi, Yoshio*
Journal of Environmental Radioactivity, 150, p.213 - 219, 2015/12
Times Cited Count：4 Percentile：13.53(Environmental Sciences)We collected sediments deposited on a sandbar from the surface to 20 cm in depth in the Abukuma River to clarify the history of radiocesium derived from the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident. We analyzed the Cs concentration in the sediments from size-fractioned samples as well as bulk samples. The results of this study demonstrated that sediment layers deposited on a sandbar retained the cumulative history of the fluvial transport of radiocesium after the FDNPP accident.
He Neutron Spin Filter (NSF) in the MLF at J-PARCSakai, Kenji; Oku, Takayuki; Hayashida, Hirotoshi*; Kira, Hiroshi*; Hiroi, Kosuke; Ino, Takashi*; Oyama, Kenji*; Okawara, Manabu*; Kakurai, Kazuhisa; Shinohara, Takenao; et al.
JPS Conference Proceedings (Internet), 8, p.036015_1 - 036015_6, 2015/09
The polarized He filter, which polarizes neutrons due to a large neutron absorption cross section of He with strong spin selectivity, becomes a convenient neutron spin filter (NSF) because it is operated immediately after its installation in beam lines without any neutron beam adjustments. For realizing such the NSF, a nuclear magnetic resonance (NMR) system is indispensable for monitoring He nuclear spin polarization 
of the NSF. We have developed the flexible NMR system based on adiabatic fast passage (AFP) and pulse NMR methods by using their complementary features. In comparing with the values of obtained by neutron transmission measurement at the beam line 10 of the J-PARC, we measured the correlations between the AFP and pulse NMR signals as changing condition of temperature, amplitude and applying period of the radio frequency field for the pulse NMR, and so on. As the results, we confirmed that our system would function enough as the monitor.
Yoshimura, Kazuya; Onda, Yuichi*; Sakaguchi, Aya*; Yamamoto, Masayoshi*; Matsuura, Yuki*
Journal of Environmental Radioactivity, 139, p.370 - 378, 2015/01
Times Cited Count：82 Percentile：93.1(Environmental Sciences)
