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Journal Articles

Anomaly of structural relaxation in complex liquid metal of bismuth; Dynamic correlation function of coherent quasi-elastic neutron scattering

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:47.28(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.

Journal Articles

Progress in R&D efforts on the energy recovery linac in Japan

Sakanaka, Shogo*; Ago, Tomonori*; Enomoto, Atsushi*; Fukuda, Shigeki*; Furukawa, Kazuro*; Furuya, Takaaki*; Haga, Kaiichi*; Harada, Kentaro*; Hiramatsu, Shigenori*; Honda, Toru*; et al.

Proceedings of 11th European Particle Accelerator Conference (EPAC '08) (CD-ROM), p.205 - 207, 2008/06

Future synchrotron light sources based on the energy-recovery linacs (ERLs) are expected to be capable of producing super-brilliant and/or ultra-short pulses of synchrotron radiation. Our Japanese collaboration team is making efforts for realizing an ERL-based hard X-ray source. We report recent progress in our R&D efforts.

JAEA Reports

Development of the external cooling device to increase the Productivity of Neutron-Transmutation-Doped Silicon Semiconductor (NTD-Si) (Joint research)

Hirose, Akira; Wada, Shigeru; Sasajima, Fumio; Kusunoki, Tsuyoshi; Kameyama, Iwao*; Aizawa, Ryoji*; Kikuchi, Naoyuki*

JAEA-Technology 2006-059, 122 Pages, 2007/01

JAEA-Technology-2006-059.pdf:26.03MB

It is expected that the demand for NTD-Si increases rapidly because of recent productive increase of hybrid-cars. In order to meet the demand, we have investigated the expansion technology of the NTD-Si productivity using the JRR3. This report describes the production of equipment for the external cooling device while proposed as one of the result of the investigation for the JRR-3 uniformity irradiation equipment. After an ingot was irradiated once, it is turned over manually and irradiated again in order irradiate the ingot uniformly. With the conventional equipment, it was necessary to wait the radioactivity of ingot decrease less than the permissible level with holding the ingot in the irradiation equipment. It was effective to shorten the waiting period by using an external cooling device for production increase of NTD-Si. It is expected that the productivity of NTD-Si will be increased by using the external cooling device.

Journal Articles

Path toward commercial fusion power plants

Okano, Kunihiko*; Kikuchi, Mitsuru; Tobita, Kenji; Hiwatari, Ryoji*

Purazuma, Kaku Yugo Gakkai-Shi, 81(11), p.839 - 848, 2005/11

no abstracts in English

JAEA Reports

Study for process and equipment design of wet gelation stages in vibropacking process

Tanimoto, Ryoji*; Kikuchi, Toshiaki*; Tanaka, Hirokazu*; Amino, Masaki*; Yanai, Minoru*

JNC TJ9420 2004-001, 258 Pages, 2004/02

JNC-TJ9420-2004-001.pdf:10.19MB

Process and layout design of external wet gelation stages in vibropacking process was examined for the feasibility study of commercialized FBR cycle system. In tbhis study, following process stages for the oxide core fuel production line were covered, that is, solidification, washing, drying, calcination, reduction, sintering stages including interim storage of sintering particles and reagent recovery stage.

Oral presentation

Pre-grouting to reduce water inflow in the ventilation shaft into the Mizunami Underground Research Laboratory

Hara, Masato; Kinoshita, Harunobu; Ikeda, Koki; Yamamoto, Masaru; Yahagi, Ryoji*; Kikuchi, Shinji*; Kawano, Hiromichi*; Ushida, Kazuhito*; Nobuto, Jun*; Minamide, Masashi*

no journal, , 

At the Mizunami Underground Research Laboratory, inflow water control to inside the tunnel has become topic. Because of this, the pre-grouting at inside the tunnnel of depth 200m was executed. In this report, it is something which is reported concerning the result of the pre-grouting.

Oral presentation

Ultra-small-angle polarized neutron scattering spectrometer SANS-J-II

Noda, Yohei; Kikuchi, Ryoji; Yamaguchi, Daisuke; Koizumi, Satoshi

no journal, , 

By use of ultra-small-angle neutron scattering spectrometer (SANS-J-II), we can study polymer and magnetic materials with focusing its hierarchical structure and dynamics properties in the length scale from nanometer to micrometer. This technique is powerful on structural analysis of softmaterials and biological materials, including water. In this sense, it is expected as a tool to observe living things as it is alive. In this presentation, the up-to-date information concerning SANS-J-II, such as the accessories for setting sample environments or a typical process for measurement and analysis, will be introduced.

Oral presentation

Current status of ultra-small-angle polarized neutron scattering equipment (SANS-J-II)

Kikuchi, Ryoji; Yamaguchi, Daisuke; Noda, Yohei; Koizumi, Satoshi*

no journal, , 

This presentation introduces latest information of ultra-small-angle polarized neutron scattering equipment (SANS-J-II) at the guide hall of Japan research reactor No.3 (JRR-3) of Japan Atomic Energy Agency. SANS-J-II is used for a static or dynamic observation of hierarchical structure from micrometer to nanometer scale in a sample. Until now, various users have visited SANS-J-II for the purpose of industrial or academic research, concerning rubber materials for tires, polymer electrolyte membrane for fuel cell, microemulsion, gel, alloy, silicon single crystal including impurity, magnetic materials and so on. As recent topics, we newly introduced a large area detector composed of 96 one-dimensional position sensitive detectors (PSD) arranged in a plane. Furthermore, in 2011, we replaced Ni-coated neutron guide tubes with 3QC supermirror-coated ones, so neutron flux is expected to increase. We are planning to verify the improved performance after the restart of JRR-3.

Oral presentation

Mechanism of the function expression caused by disordered structure

Kawakita, Yukinobu; Li, B.; Kawasaki, Takuro; Kikuchi, Tatsuya*; Kiyanagi, Ryoji; Inamura, Yasuhiro; Ohara, Takashi; Shibata, Kaoru; Kofu, Maiko; Nakamura, Mitsutaka; et al.

no journal, , 

Research results obtained in JAEA Project Research "Mechanism of the function expression caused by disordered structure" will be focused in this presentation. The purpose of this project is to reveal mechanism of the function expression of functional materials where randomness involved in crystalline structure plays an key role, by applying the method and analyses frequently used in random material physics. We will report the results of liquid bismuth with complex structure which was investigated by time-space correlation function, and low thermal conductivity in layered thermoelectric material and next-generation solar cell which was investigated by neutron inelastic scattering measurements.

Oral presentation

Time-space correlation function of liquid metals with complex static structure deduced from pulsed neutron experiment

Kawakita, Yukinobu; Kikuchi, Tatsuya*; Inamura, Yasuhiro; Tahara, Shuta*; Maruyama, Kenji*; Hanashima, Takayasu*; Nakamura, Mitsutaka; Kiyanagi, Ryoji; Yamauchi, Yasuhiro*; Chiba, Kaori*; et al.

no journal, , 

There are many polyvalent liquid metals with complex structure which cannot be reproduced by random packing model. To explain such complexity, coexistence of metallic and covalent bonds, dynamic model of short-lived covalent bonds, and quasi-crystal model where Peierls distortion still remains even in liquid phase have been proposed from structure analyses and theoretical calculations. To obtain concrete picture experimentally for complex structure, it is indispensable to measure dynamic structure with precise statistical accuracy. We performed inelastic neutron scattering of liquid bismuth by using AMATERAS installed at MLF in J-PARC and deduced its time-space correlation function. We got evidence that structure of Peierls distortion remains even in liquid by evaluating difference in relaxation time at specific atomic distances characterized by double layered structure.

Oral presentation

Structural relaxation and time-space correlation function of liquid metals with complex structure

Kawakita, Yukinobu; Kikuchi, Tatsuya*; Inamura, Yasuhiro; Tahara, Shuta*; Maruyama, Kenji*; Hanashima, Takayasu*; Nakamura, Mitsutaka; Kiyanagi, Ryoji; Yamauchi, Yasuhiro*; Chiba, Kaori*; et al.

no journal, , 

We have performed coherent quasielastic neutron scattering experiment for liquid polyvalent metals which has complicated static structure not reproduced by a hard-sphere packing model, by utilizing AMATERAS spectrometer in J-PARC. It has been considered that, for Bi and Sb, a double-layered structure originated from Peierls distortion which is seen in solid crystalline phase remains even in their liquid phases. We have succeeded in detection of such Peierls distortion structure in liquid by difference in structural relaxation time at corresponding charateristic interatomic distances in the deduced time-space correlation function.

Oral presentation

Real time and real space analysis for atomic dynamics in liquids

Kawakita, Yukinobu; Kikuchi, Tatsuya*; Inamura, Yasuhiro; Tahara, Shuta*; Maruyama, Kenji*; Hanashima, Takayasu*; Nakamura, Mitsutaka; Kiyanagi, Ryoji; Yamauchi, Yasuhiro*; Chiba, Kaori*; et al.

no journal, , 

We have developed analysis method to reduce the so-call van Hove function, a time-space correlation function, through the regularization method for coherent quasielastic neutron scattering (QENS) of liquids. In principle, the van Hove function in r-t space can be obtained by double Fourier transform from dynamic structure factor in Q-E space. Instead of a direct function estimation of the van Hove function through the regularization method which easily involves systematical deviation of the calculated dynamic structure factor from the experimental dynamic structure factor, we used a mediation function between them and estimated it through the regularization method. We will discuss with the properties of the mediation function and the obtained van Hove function and the calculated dynamic structure factor with an example of liquid metals with complex static structure such as Bi and Sb whose QENS were measured by AMATERAS spectrometer in J-PARC.

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