Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Yuguchi, Takashi*; Yamazaki, Hayato*; Ishibashi, Kozue*; Sakata, Shuhei*; Yokoyama, Tatsunori; Suzuki, Satoshi*; Ogita, Yasuhiro; Sando, Kazusa*; Imura, Takumi*; Ono, Takeshi*
Journal of Asian Earth Sciences, 226, p.105075_1 - 105075_9, 2022/04
Times Cited Count:4 Percentile:54.83(Geosciences, Multidisciplinary)Simultaneous determination of the U-Pb age of zircon and concentration of titanium in a single analysis spot, using inductively coupled plasma mass spectrometry with laser ablation sample introduction, produces paired age and temperature data of zircon crystallisation, potentially revealing time-temperature () histories for evolved magma. The Kurobegawa granite, central Japan, contains abundant mafic magmatic enclaves (MMEs). We applied this method to evaluate MMEs and their host (enclosing) granites. Cooling behaviour common to both MMEs and host rocks was found between 1.5 and 0.5 Ma. Rapid cooling from the zircon crystallisation temperature to the closure temperature of biotite K-Ar system was within
1 million year. Combining the obtained
paths of MMEs and host rocks with petrological information can provide insights into magma chamber processes. This suggests that MME flotation, migration, and spread through the magma chamber ceased at 1.5-0.5 Ma, indicating the emplacement age of the Kurobegawa granitic pluton, as no large-scale reheating episodes have occurred since then.
Gtz, M.*; Yakushev, A.*; G
tz, S.*; Di Nitto, A.*; D
llmann, Ch. E.*; Asai, Masato; Kindler, B.*; Krier, J.*; Lommel, B.*; Nagame, Yuichiro*; et al.
Radiochimica Acta, 110(2), p.75 - 86, 2022/02
Times Cited Count:2 Percentile:29.53(Chemistry, Inorganic & Nuclear)The study of volatile superheavy element carbonyl complexes requires more efficient methods because the yield of transactinide elements decreases with increasing atomic number. This is achieved by using a newly developed double chamber system to separate the recoil chamber and the reaction one, thereby avoiding the decomposition of reactive molecules by the projectile ion beam, which hinders the synthesis of carbonyl complexes. The feasibility of this method was verified by synthesizing 5d metal short-lived isotopes as homologous element isotopes of the light transactinide elements Sg, Bh, Hs, and Mt at the Japan Atomic Energy Agency tandem accelerator and conducting model experiments.
Chiera, N. M.*; Sato, Tetsuya; Eichler, R.*; Tomitsuka, Tomohiro; Asai, Masato; Adachi, Sadia*; Dressler, R.*; Hirose, Kentaro; Inoue, Hiroki*; Ito, Yuta; et al.
Angewandte Chemie; International Edition, 60(33), p.17871 - 17874, 2021/08
Times Cited Count:3 Percentile:21.36(Chemistry, Multidisciplinary)The formation and the chemical characterization of single atoms of dubnium (Db, element 105), in the form of its volatile oxychloride, was investigated using the on-line gas phase chromatography technique, in the temperature range 350 - 600 C. Under the exact same chemical conditions, comparative studies with the lighter homologs of group-5 in the Periodic Table clearly indicate the volatility sequence being NbOCl
TaOCl
DbOCl
. From the obtained experimental results, thermochemical data for DbOCl
were derived. The present study delivers reliable experimental information for theoretical calculations on the chemical properties of transactinides.
Chiera, N. M.; Sato, Tetsuya; Tomitsuka, Tomohiro; Asai, Masato; Ito, Yuta; Shirai, Kaori*; Suzuki, Hayato; Tokoi, Katsuyuki; Toyoshima, Atsushi; Tsukada, Kazuaki; et al.
Journal of Radioanalytical and Nuclear Chemistry, 320(3), p.633 - 642, 2019/06
Times Cited Count:2 Percentile:20.94(Chemistry, Analytical)An isothermal gas-chromatographic (IGC) device has been developed and tested for on-line gas phase studies of volatile oxychlorides of short-lived group-5 transition metals. Radioisotopes of niobium and tantalum, produced in nuclear fusion evaporation reactions, are directly flushed into the IGC setup by an inert gas-jet. Oxychloride compounds are formed by the addition of SOCl and O
. Parameters influencing the formation and transport of NbOCl
and TaOCl
are investigated. For nuclides with half-lives (
) of about 30 s, an overall efficiency of 7% is obtained, rendering the IGC setup suitable for the chemical exploration of
Db(
= 34s).
Chiera, N. M.; Sato, Tetsuya; Tomitsuka, Tomohiro; Asai, Masato; Suzuki, Hayato*; Tokoi, Katsuyuki; Toyoshima, Atsushi; Tsukada, Kazuaki; Nagame, Yuichiro
Inorganica Chimica Acta, 486, p.361 - 366, 2019/02
Times Cited Count:4 Percentile:24.55(Chemistry, Inorganic & Nuclear)The formation of NbOCl and TaOCl
and their adsorption behavior on quartz surfaces was explored by applying an isothermal gas-chromatographic method. Trace amounts of short-lived Nb and Ta isotopes were used. Adsorption enthalpy values (
) at zero surface coverage of -
(NbOCl
) = 102
4 kJ/mol and -
(TaOCl
) = 128
5 kJ/mol were determined by analyzing the chromatographic behavior of the Nb andTa complexes with a Monte-Carlo simulation method based on an adsorption-desorption kinetic model.By applying an empirical correlation, the experimental
values were successively related to the macroscopic standard sublimation enthalpy,
, as a measure of the volatility of each substance. The inferred sublimation enthalpies are in agreement with tabulated thermochemical values. Thus, the linear empirical correlation between
and
for metal-oxychlorides was updated with the inclusion of the present data. According to the predicted
(DbOCl
), a
(DbOCl
) value of 135
2 kJ/mol was extrapolated. The future accomplishment of comparative studies with DbOCl
under the same experimental conditions will provide valuable information on the volatility trend in Group-5 elements, together with an indication on the magnitude of relativistic effects on the electronic structure of dubnium.
Yoshida, Kensuke*; Fujioka, Shinsuke*; Higashiguchi, Takeshi*; Ugomori, Teruyuki*; Tanaka, Nozomi*; Kawasaki, Masato*; Suzuki, Yuhei*; Suzuki, Chihiro*; Tomita, Kentaro*; Hirose, Ryoichi*; et al.
Applied Physics Letters, 106(12), p.121109_1 - 121109_5, 2015/03
Times Cited Count:10 Percentile:43.95(Physics, Applied)Yoshida, Kensuke*; Fujioka, Shinsuke*; Higashiguchi, Takeshi*; Ugomori, Teruyuki*; Tanaka, Nozomi*; Ohashi, Hayato*; Kawasaki, Masato*; Suzuki, Yuhei*; Suzuki, Chihiro*; Tomita, Kentaro*; et al.
Applied Physics Express, 7(8), p.086202_1 - 086202_4, 2014/08
Times Cited Count:29 Percentile:74.35(Physics, Applied)We demonstrate high conversion efficiency for extreme ultraviolet (EUV) emission at 6.5-6.7 nm from multiple laser beam-produced one-dimensional spherical plasmas. Multiply charged-state ions produce strong resonance emission lines, which combine to yield intense unresolved transition arrays in Gd, Tb, and Mo. The maximum in-band EUV conversion efficiency was observed to be 0.8%, which is one of the highest values ever reported due to the reduction of plasma expansion loss.
Suzuki, Chihiro*; Kato, Takako*; Sato, Kuninori*; Tamura, Naoki*; Kato, Daiji*; Sudo, Shigeru*; Yamamoto, Norimasa*; Tanuma, Hajime*; Ohashi, Hayato*; Suda, Shintaro*; et al.
Journal of Physics; Conference Series, 163, p.012019_1 - 012019_4, 2009/06
Times Cited Count:11 Percentile:94.18(Physics, Multidisciplinary)We have measured EUV spectra from highly charged tin ions in low density plasmas produced in the Large Helical Device (LHD). The well known dense spectral structure around 13.5 nm is measured when the plasma is rapidly cooled and approaching radioactive collapse, while the sparse spectrum with several unidentified discrete lines from 13.8-14.6 nm is observed if the plasma is cooled more slowly. The dominant charge states in the former case are Sn -Sn
. The latter case may be explained by considering the spectral lines from charge states higher than Sn
.
Sayama, Hayatoshi*; Suzuki, Kazuhiko*; Shimada, Yukiyasu*
PNC TJ1612 96-001, 84 Pages, 1996/03
no abstracts in English
Sayama, Hayatoshi*; Suzuki, Kazuhiko*; Shimada, Yukiyasu*
PNC TJ1612 95-001, 39 Pages, 1995/03
no abstracts in English
Asai, Masato; Tsukada, Kazuaki; Hirose, Kentaro; Toyoshima, Atsushi*; Tomitsuka, Tomohiro*; Chiera, N. M.*; Ito, Yuta; Makii, Hiroyuki; Nagame, Yuichiro*; Nishio, Katsuhisa; et al.
no journal, ,
Neutron-rich fermium isotopes Fm and
Fm and lawrencium isotope
Lr were produced in the multinucleon transfer reaction on
Es target with heavy-ion beam and in the heavy-ion fusion reaction on
Cm target with
N beam, respectively. Reaction products were mass-separated with an on-line isotope separator (ISOL), and spontaneous fission (SF) of these isotopes were measured. It was found that the mass distribution of the SF of
Fm was asymmetric, while that of
Fm was sharp symmetric, which confirmed the previous experimental results. On the other hand, the SF of
Lr seemed to contain both symmetric and asymmetric mass distributions. On the basis of the present results of the mass and total kinetic energy distributions, we discussed the mechanism of fission for these isotopes.
Miyahara, Naoya*; Maejima, Hayato*; Suzuki, Eriko; Osaka, Masahiko; Sato, Isamu*
no journal, ,
In the decommissioning of the Fukushima-Daiichi Nuclear Power Station, a large amount of radioactive concrete waste should be generated. For the waste management, its appropriate treatment based on the accurate information of the inventory and the contamination aspect of radioactive Cs is of importance. In particular, accurate estimation for Cs penetration into concrete by immersion to the contaminated water should be required. Thus, we have launched a development of CFD-based simulation method which is expected to help evaluate the Cs penetration behavior into concrete. In this presentation, a first trial simulation is given for the reproduction of experimental result for Cs penetration into homogeneous concrete for confirmation of the applicability of this method by considering the most basic physical parameter, Cs diffusion.
Asai, Masato; Suekawa, Yoshihide*; Higashi, Masato*; Kamada, Hiroki*; Tobe, Teruhisa*; Andreyev, A. N.; Hirose, Kentaro; Ito, Yuta; Makii, Hiroyuki; Nishio, Katsuhisa; et al.
no journal, ,
A new isomer Np with a half-life of
9 min has been discovered. It was produced in the reaction of
U target with
Li beam at JAEA tandem accelerator, and was identified through characteristic X-ray measurement and mass separation with an on-line isotope separator (ISOL). Gamma-ray singles, gamma-gamma coincidence, and internal-conversion electron measurements were performed. It was revealed that the
Np decays mostly through an isomeric E4 transition followed by an M1 transition, and that the spin-parity of the
Np should be 5
. The results are introduced in detail, and the nuclear structure of the
Np are discussed.
Asai, Masato; Suekawa, Yoshihide*; Higashi, Masato*; Kamada, Hiroki*; Tobe, Teruhisa*; Andreyev, A. N.; Hirose, Kentaro; Ito, Yuta; Makii, Hiroyuki; Nishio, Katsuhisa; et al.
no journal, ,
We have carried out experiments to study nuclear structure of the new isomer Np which we discovered recently. The
Np was produced in the reaction of
U target with
Li beam at JAEA tandem accelerator, and was mass-separated with an on-line isotope separator (ISOL). The half-life was determined accurately through LX-ray measurements. The
transition emitted by following the isomeric transition was successfully observed through LX-
coincidence measurements. Moreover, the multipolarities of the
transitions were determined with internal-conversion electron measurements. On the basis of these experimental results, We have clarified excitation energy, spin-parity, and nuclear structure of
Np.
Sato, Tetsuya; Chiera, N. M.*; Tomitsuka, Tomohiro; Tokoi, Katsuyuki*; Suzuki, Hayato*; Ito, Yuta; Asai, Masato; Shirai, Kaori*; Inoue, Hiroki*; Adachi, Sadia*; et al.
no journal, ,
The influence of strong relativistic effects on chemical properties has been interesting in the superheavy element region. Their chemical properties, however, have not been investigated sufficiently because of experimental difficulties owing to their low production rates and short half-lives. In order to elucidate the chemical properties of dubnium (Db, Z = 105), we have conducted on-line isothermal gas chromatographic experiments of oxychloride of group-5 elements. We confirmed the formation of volatile oxychlorides of Db and its lighter homologs Nb and Ta by using Db (half-life,
= 33.8 s),
Nb (
= 14.5 min.), and
Ta (
= 6.76 min.), respectively. We successfully determined the adsorption enthalpies of the oxychlorides of each element on the quartz surface from their isothermal gas chromatographic behavior. The obtained volatility sequence of the group-5 elements is found to be Nb
Ta
Db.
Saito, Akihito*; Iwata, Masayuki*; Sato, Hayato*; Arai, Tsuyoshi*; Nagayama, Katsuhisa*; Suzuki, Tatsuya*; Horiguchi, Kenichi; Sugaya, Atsushi
no journal, ,
no abstracts in English
Yamashita, Hayato; Onizawa, Takashi; Takaya, Shigeru; Enuma, Yasuhiro; Wakai, Takashi; Kato, Shoichi; Suzuki, Akihiro*
no journal, ,
This study proposes an appropriate method to convert the load parameter in small punch creep (SPC) tests to that in uniaxial creep tests for Mod.9Cr-1Mo steel at operating temperature of future fast reactors. It is impossible to simply compare the results of SPC tests to those of uniaxial creep tests, because the load parameters in those creep tests are load and stress, respectively. Conventionally, load/stress conversion coefficient (F/) has been employed to compare the results of SPC and uniaxial creep tests. Though the applicability of F/
has been demonstrated in the temperature region considerably higher than 550
C that is the operating temperature of future fast reactors, the applicability has not been demonstrated at 550
C. Therefore, this paper studies an appropriate method to obtain F/
. F/
calculated from finite element analysis (FEA) and that based on fracture ductility was too small to convert SPC results. In contrast, it was clarified that conversion was possible using F/
based on Arrhenius-type equation.
Chiera, N. M.; Sato, Tetsuya; Asai, Masato; Suzuki, Hayato*; Tokoi, Katsuyuki; Tomitsuka, Tomohiro; Toyoshima, Atsushi; Tsukada, Kazuaki; Nagame, Yuichiro
no journal, ,
Tomitsuka, Tomohiro; Tokoi, Katsuyuki; Sato, Tetsuya; Ito, Yuta; Suzuki, Hayato*; Asai, Masato; Tsukada, Kazuaki; Toyoshima, Atsushi; Chiera, N. M.; Goto, Shinichi*; et al.
no journal, ,
In order to experimentally determine the ground state electronic configurations of Superheavy element atoms, we have developed a slow Atomic Beam Source (ABS) using a high-temperature nozzle type cavity. In this study, we conducted an off-line experiment using stable isotopes of Cd to examine the extraction of the Cd beams. A symmetrical beam distribution with respect to the atomic beam edge was obtained. The obtained results, together with Monte-Carlo simulations for atomic beam profiles, will be presented.
Asai, Masato; Tsukada, Kazuaki; Hirose, Kentaro; Toyoshima, Atsushi*; Tomitsuka, Tomohiro*; Chiera, N. M.*; Ito, Yuta; Makii, Hiroyuki; Nagame, Yuichiro*; Nishio, Katsuhisa; et al.
no journal, ,
We have studied spontaneous fission of neutron-rich Fm and Lr isotopes. The neutron-rich Fm isotopes were produced with the Es target and the
O beam delivered by the JAEA tandem accelerator. The neutron-rich Lr isotope were produced with the
Cm target and the
N beam. Reaction products were mass-separated with an on-line isotope separator (ISOL), which enabled us to obtain non-contaminated samples and to measure fission fragments precisely. From the deduced fission-fragment mass and total kinetic energy distributions, we have obtained a new insight into the competition between the symmetric and asymmetric fission which is characteristic in this neutron-rich region.