Simultaneous determination of zircon crystallisation age and temperature; Common thermal evolution of mafic magmatic enclaves and host granites in the Kurobegawa granite, central Japan

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

https://doi.org/10.1016/j.jseaes.2021.105075

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.

Optimization of an isothermal gas-chromatographic setup for the chemical exploration of dubnium (Db, Z = 105) oxychlorides

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

https://doi.org/10.1007/s10967-019-06505-w

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).

Density and X-ray emission profile relationships in highly ionized high-Z laser-produced plasmas

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

https://doi.org/10.1063/1.4916395

EUV spectra from highly charged tin ions observed in low density plasma in LHD

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

https://doi.org/10.1088/1742-6596/163/1/012019

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.

Development of a Monte Carlo simulation code for analyses of adsorption and desorption behavior of short-lived isotopes in a surface ion-source

Tokoi, Katsuyuki; Sato, Tetsuya; Eichler, R.*; Ito, Yuta; Tomitsuka, Tomohiro; Suzuki, Hayato*; Asai, Masato; Tsukada, Kazuaki; Toyoshima, Atsushi*; Chiera, N. M.; et al.

no journal, , 

We developed a new experimental method combining vacuum chromatography and surface ionization, and applied this to investigate adsorption behavior of lawrencium (Lr, Z =103) on a surface of high temperature metallic tantalum. The adsorption behavior of Lr was similar to that of lutetium having low volatility among lanthanide elements. In this work, a Monte Carlo simulation code has been newly developed to study ionization and chromatographic behavior of short-lived atoms. In the presentation, we will report the details of a developed simulation code and calculation results.

Development of a slow atomic beam source for superheavy elements

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.

Development of a CFD-BASED simulation method for cesium penetration into concrete

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.

Spontaneous fission studies for neutron-rich Fm and Lr isotopes

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.

Spontaneous fission measurements for neutron-rich Fm and Lr isotopes using Es target

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.

Decay and nuclear structure of Np isomer

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.