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Journal Articles

Powder neutron diffraction of La-apatite under low temperature

Matsushita, Yoshitaka*; Izumi, Fujio*; Kobayashi, Kiyoshi*; Igawa, Naoki; Kitazawa, Hideaki*; Oyama, Yukiko*; Miyoshi, Shogo*; Yamaguchi, Shu*

Nuclear Instruments and Methods in Physics Research A, 600(1), p.319 - 321, 2009/02

https://doi.org/10.1016/j.nima.2008.11.081
 Times Cited Count：22 Percentile：80.29(Instruments & Instrumentation)

The neutron powder diffraction data of the apatite-type La-silicate La$$_{9.5}$$Si$$_{6}$$O$$_{26.25}$$ was measured at 10 K and the Rietveld refinement on the basis of hexagonal P6$$_{3}$$/m was successfully carried out. The obtained cell parameters were ${it a}$ =0.971297(7) nm, and ${it c}$ = 0.717950(6) nm. On the Rietveld refinement supported by maximum entropy method, the interstitial oxygen positions show randomly distribution around La2 site, and they may give the driving-force of high ionic conductivity to the main ionic conduction site O4.

Journal Articles

Water-based sol-gel synthesis and crystal structure refinement of lanthanum silicate apatite

Kobayashi, Kiyoshi*; Matsushita, Yoshitaka*; Igawa, Naoki; Izumi, Fujio*; Nishimura, Chikashi*; Miyoshi, Shogo*; Oyama, Yukiko*; Yamaguchi, Shu*

Solid State Ionics, 179(38), p.2209 - 2215, 2008/11

https://doi.org/10.1016/j.ssi.2008.07.023
 Times Cited Count：24 Percentile：67.72(Chemistry, Physical)

A novel synthesis method of lanthanum silicate apatite was developed by a sol-gel method using an aqueous solution system. The processes of apatite phase formation were investigated by XRD and TG-DTA. Lanthanum dioxide carbonate was found in the sample below 873 K and lanthanum silicate apatite was formed above 1073 K. It was founded that the profiles of powder XRD and neutron diffraction could be refined by the oxy-apatite structure with the space group ${it P}$6$$_{3}$$/${it m}$.

JAEA Reports

Study on a collapse mechanism of a junction between greatly deeper shaft and horizontal drifts (Contract research)

Kurosaki, Yukio*; Yamachi, Hiroshi*; Katsunuma, Yoshio*; Nakata, Masao*; Kuwahara, Hideki*; Yamada, Fumitaka*; Matsushita, Kiyoshi*; Sato, Toshinori*

JAEA-Research 2008-048, 274 Pages, 2008/03

JAEA-Research-2008-048.pdf:10.93MB

A junction space between a super deep shaft and horizontal drifts forms a 3-dimensional geo-structure, which would take a complicated mechanical behavior during a junction excavation. However, a quantitative design method for a deep junction has not yet established. In order to examine a collapse mechanism of super deep shaft junction, we have conducted literature surveys and interview studies concerned with a collapses. Considering the results of investigations with reviews of intellectuals, the collapse mechanism depends on both a construction procedure of shaft junction and a geological condition. On the other hand, where a deep junction intersects faults and/or fractures with a large angle, a collapse called taka-nuke may occur and a numerical studies that can simulate a practical rock mass behavior around a shaft junction should be carry out. We demonstrate finite difference method is most adequate for these simulations with intellectual review.

Journal Articles

Effect of energy relaxation of H$$^{0}$$ atoms at the wall on the production profile of H$$^{-}$$ ions in large negative ion sources

Takado, Naoyuki*; Matsushita, Daisuke*; Fujino, Ikuro*; Hatayama, Akiyoshi*; Tobari, Hiroyuki; Inoue, Takashi

Review of Scientific Instruments, 79(2), p.02A503_1 - 02A503_4, 2008/02

https://doi.org/10.1063/1.2802583
 Times Cited Count：2 Percentile：14.57(Instruments & Instrumentation)

Production and transport process of the H$$^{0}$$ atoms are numerically simulated using a three-dimensional Monte Carlo transport code. The code was applied to the "JAEA 10 ampere negative ion source" under Cs-seeded condition to obtain a spatial distribution of surface-produced H$$^{0}$$ ions. In this analysis, we focus on the effect of the energy relaxation of the H$$^{0}$$ atoms at the wall on the H$$^{-}$$ ion production from the H$$^{0}$$ atoms. The result indicates that, by considering the energy relaxation of the H$$^{0}$$ atoms at the wall, the production profile of the surface-produced H$$^{-}$$ ion is well reflected in the production profile of the H$$^{0}$$ atom production.

Journal Articles

Numerical analysis of H$$^{-}$$ ion transport processes in Cs-seeded negative ion sources

Matsushita, Daisuke*; Takado, Naoyuki*; Hatayama, Akiyoshi*; Inoue, Takashi

Review of Scientific Instruments, 79(2), p.02A527_1 - 02A527_4, 2008/02

https://doi.org/10.1063/1.2804898
 Times Cited Count：5 Percentile：28.22(Instruments & Instrumentation)

The H$$^{-}$$ ion transport processes are numerically simulated to understand the extraction process of surface-produced H$$^{-}$$ ions. The three-dimensional transport code using Monte Carlo method has been applied to calculate the H$$^{-}$$ ion extraction probabilities in the model geometry of the JAEA 10 ampere negative ion source. The roles of (1) filter magnetic field and (2) collisions with neutrals (H$$^{0}$$ atoms and H$$_{2}$$ molecules) on the H$$^{-}$$ ion extraction are systematically studied. The results show that H$$^{-}$$ ions are extracted mainly by the filter magnetic field under the low gas pressure condition. The simulation results of extracted H$$^{-}$$ ion beam intensity in the JAEA 10 ampere negative ion source without the magnetic filter tend to be smaller than the experimental results, especially under the low pressure condition.

Journal Articles

Intraoperative boron neutron capture therapy using thermal/epithermal mixed beam

Matsumura, Akira*; Yamamoto, Tetsuya*; Shibata, Yasushi*; Nakai, Kei*; Zhang, T.*; Matsushita, Akira*; Takano, Shingo*; Endo, Kiyoshi*; Akutsu, Hiroyoshi*; Yamamoto, Kazuyoshi; et al.

Research and Development in Neutron Capture Therapy, p.1073 - 1078, 2002/09

Since 1998 to 2002, a new clinical trial of an intraoperative boron neutron capture therapy (IOBNCT) at JRR-4 of Japan Atomic Energy Institute (JAERI) using BSH with mixed thermal/epithermal neutron beam has been accomplished. There have been 9 patients included in this study. The median survival time (MST) in GBM was 19.8 months and 16.8 months in AA. IOBNCT with mixed thermal/epithermal neutron beam provide better primary radiation effect than conventional therapy in selected cases. Our phase I/II clinical trial was effective in local tumor control. Further clinical trial with new design should be performed to prove the efficacy of IOBNCT.

Journal Articles

Comparison of patient brain dose measurements and the JCDS calculation

Yamamoto, Tetsuya*; Matsumura, Akira*; Yamamoto, Kazuyoshi; Kumada, Hiroaki; Torii, Yoshiya; Endo, Kiyoshi*; Matsushita, Akira*; Shibata, Yasushi*; Nose, Tadao*

Research and Development in Neutron Capture Therapy, p.415 - 418, 2002/09

Dose measurements in a patient's brain undergoing intraoperative BNCT (IOBNCT) were compared with calculations by a JAERI computational dosimetry system (JCDS). The maximum thermal neutron flux on the brain surface from the postirradiation measurement averaged 2.33$$pm$$0.37($$times$$10$$^{9}$$cm$$^{-2}$$s$$^{-1}$$) and the vascular boron dose averaged 11.4$$pm$$1.2 (9.6-12.7) Gy. Using JCDS, the maximum thermal neutron flux in the irradiated volume averaged 2.21$$pm$$0.33($$times$$10$$^{9}$$cm$$^{-2}$$s$$^{-1}$$), while the target vascular dose averaged 5.7 Gy and varied from 3.5 to 7.8 Gy. As such, in the dose planning for intra-operative irradiation, practical use of JCDS is recommended for uniform volume-dose control of postsurgical brain in IOBNCT.

Journal Articles

In-air radiobiological dosimetry of JRR-4 neutron beams for boron neutron capture therapy

Yamamoto, Tetsuya*; Matsumura, Akira*; Yamamoto, Kazuyoshi; Kumada, Hiroaki; Hori, Naohiko; Torii, Yoshiya; Endo, Kiyoshi*; Matsushita, Akira*; Yoshida, Fumiyo*; Shibata, Yasushi*; et al.

Research and Development in Neutron Capture Therapy, p.697 - 700, 2002/09

The RBE of dose components generated in boron neutron capture therapy (BNCT) were separately determined in neutron beams at JRR-4. The cell killing effect of the neutron beam with or without the presence of 10B was highly dependent on the neutron beam used, according to the epithermal and fast neutron content in the beam. RBE (BARBEboron) values of the boron capture reaction for an epithermal (ENB), a mixed thermal-epithermal (TNB-1), and a thermal (TNB-2) neutron beams were 3.99$$pm$$0.24, 3.04$$pm$$0.19 and 1.43$$pm$$0.08, respectively.

Journal Articles

Basic and clinical studies for application of epithermal neutron beam for neutron capture therapy

Nose, Tadao*; Matsumura, Akira*; Yamamoto, Tetsuya*; Shibata, Yasushi*; Yoshida, Fumiyo*; Akutsu, Hiroyoshi*; Yasuda, Susumu*; Matsushita, Akira*; Nakai, Kei*; Yamada, Takashi*; et al.

UTRCN-G-29, p.114 - 123, 2001/00

no abstracts in English

Journal Articles

Intraoperative boron neturon capture therapy for malignant gliomas; First clinical results of Tsukuba phase I/II trial using JAERI mixed thermal-epithermal beam

Matsumura, Akira*; Yamamoto, Tetsuya*; Shibata, Yasushi*; Akutsu, Hiroyoshi*; Yasuda, Susumu*; Matsushita, Akira*; Nakai, K.*; Yamada, Takashi*; Takano, Shingo*; Mizutani, Taro*; et al.

Proceedings of 9th International Symposium on Neutron Capture Therapy for Cancer, p.29 - 30, 2000/10

no abstracts in English

Oral presentation

Synthesis, crystal structure refinement, and ionic transport properties of lantanum silicate with apatite structure

Kobayashi, Kiyoshi*; Yoshida, Akira*; Matsushita, Yoshitaka*; Nishimura, Chikashi*; Oyama, Yukiko*; Miyoshi, Shogo*; Izumi, Fujio*; Igawa, Naoki; Yamaguchi, Shu*

no journal, , 

Conduction properties of oxide ions and crystal structure refinement of La$$_{9.50}$$(SiO$$_{4}$$)$$_{6}$$O$$_{2.25}$$ have been made by A.C.-impedance, electro-motive force of oxygen concentration cell, X-ray and neutron diffraction methods using the sample fabricated by the sol-gel method. The crystal structure of the sample can be refined by structural model with ${it P}$6$$_{3}$$/${it m}$ space group. Oxide ion conductivity is found to be predominant in wide oxygen partial pressure and temperature range based on the conductivity and electro-motive force measurements.

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