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Journal Articles

Crystal structure and electron density distribution analyses of Nd$$_{x}$$Ce$$_{1-x}$$O$$_{2-delta}$$ for electrolyte by Rietveld/ maximum entropy method

Taguchi, Tomitsugu; Igawa, Naoki; Birumachi, Atsushi; Asaoka, Hidehito; Miwa, Shuhei; Osaka, Masahiko

e-Journal of Surface Science and Nanotechnology (Internet), 13, p.339 - 342, 2015/06

Rare-earth doped ceria exhibits both ionic and electronic conductions, and those ceria with higher ratio of ionic conduction against electronic conduction is used as a solid electrolyte for solid oxide fuel cells. The electron density distributions in crystals are closely related to the electron diffusing pathway which affects the electronic conduction. In this study, we investigated the electron density distribution of doped ceria as a function of the content of Nd$$_{2}$$O$$_{3}$$-dopant to deduce the ratio of the electronic to ionic conduction. The crystal structure was refined with the space group, ${it Fm}$-3${it m}$, which is the same as undoped ceria. Ce and Nd ions randomly occupied the 4${it a}$ site and O ion the 8${it c}$ site. The electron conduction pathway was distributed through the 4${it a}$-8${it c}$ and 8${it c}$-8${it c}$ sites. The relationship between crystal structural change and electron density distribution as a function of the content of Nd$$_{2}$$O$$_{3}$$ dopant will be discussed.

Journal Articles

Nuclear and electron density distributions of LiMn$$_{2}$$O$$_{4}$$ analyzed by combination of Rietveld/ maximum entropy method

Igawa, Naoki; Kodama, Katsuaki; Birumachi, Atsushi; Taguchi, Tomitsugu

e-Journal of Surface Science and Nanotechnology (Internet), 13, p.247 - 252, 2015/05

The nuclear and electron density distributions of LiMn$$_{2}$$O$$_{4}$$ which is one of the primitive cathode materials for secondary Li-ion batteries, were analyzed by applying Rietveld refinement and MEM to neutron and X-ray diffraction data, to estimate the Li diffusing pathway. The crystal structure of LiMn$$_{2}$$O$$_{4}$$ could be refined with the space group, ${it Fd}$-3${it m}$ in the temperature range from 240 to 573 K. The structure was transformed to ${it Fddd}$ below 240 K. The isotropic thermal displacement parameter of Li was proportional to the temperature excluding 240 to 300 K. According to the MEM analyses it was indicated that the Li ions diffuse through 8${it b}$ and 16${it e}$ around 300 K.

Journal Articles

Neutron-sensitive ZnS/$$^{10}$$B$$_{2}$$O$$_{3}$$ ceramic scintillator detector as an alternative to a $$^{3}$$He-gas-based detector for a plutonium canister assay system

Nakamura, Tatsuya; Ozu, Akira; To, Kentaro; Sakasai, Kaoru; Suzuki, Hiroyuki; Honda, Katsunori; Birumachi, Atsushi; Ebine, Masumi; Yamagishi, Hideshi*; Takase, Misao; et al.

Nuclear Instruments and Methods in Physics Research A, 763, p.340 - 346, 2014/05

 Times Cited Count:2 Percentile:77.01(Instruments & Instrumentation)

A neutron-sensitive ZnS/$$^{10}$$B$$_{2}$$O$$_{3}$$ ceramic scintillator detector was developed as an alternative to a $$^{3}$$He-gas-based detector for use in a plutonium canister assay system. The detector has a modular structure, with a flat ZnS/$$^{10}$$B$$_{2}$$O$$_{3}$$ceramic scintillator strip that is installed diagonally inside a light-reflecting aluminium case with a square cross section. The prototype detectors, which have a neutron-sensitive area of 30 mm $$times$$ 250 mm, exhibited a sensitivity of 21.7-23.4 $$pm$$ 0.1 cps$$/$$nv for thermal neutrons, a $$^{137}$$Cs $$gamma$$-ray sensitivity of 1.1-1.9 $$pm $$0.2 $$times$$ 10$$^{-7}$$ and a count variation of less than 6% over the detector length. A trial experiment revealed a temperature coefficient of less than -0.24$$pm$$ 0.05% / $$^{circ}$$C over the temperature range of 20-50$$^{circ}$$C.

Journal Articles

A Position-sensitive tubular scintillator-based detector as an alternative to a $$^{3}$$He-gas-based detector for neutron-scattering instruments

Nakamura, Tatsuya; Katagiri, Masaki*; To, Kentaro; Honda, Katsunori; Suzuki, Hiroyuki; Ebine, Masumi; Birumachi, Atsushi; Sakasai, Kaoru; Soyama, Kazuhiko

Nuclear Instruments and Methods in Physics Research A, 741, p.42 - 46, 2014/03

 Times Cited Count:5 Percentile:52.58(Instruments & Instrumentation)

A position-sensitive tubular scintillator-based neutron detector is proposed as an alternative to a $$^{3}$$He-gas-based detector. The detector has a neutron-detecting element constructed from rolled ZnS/$$^{6}$$LiF scintillator screens that sandwich wavelength-shifting (WLS) fibre coils (SFC element). Multiple SFC elements are enclosed in an aluminium tube in a row to form a one-dimensional position-sensitive neutron detector. The design of the WLS fibre coil, which was determined by performing basic experiments, comprised two 0.75-mm-diameter WLS fibres wound in parallel at a pitch of 1.5 mm. A 64-element detector with a pixel size of 22 mm $$times$$ 20 mm (width $$times$$ length) successfully demonstrated the detection principle. The tubular shape of the new detector is similar to the usual 25-mm-diameter $$^{3}$$He tube, making this an alternative detector with the potential to be installed in a vacuum tank for inelastic-neutron-scattering instruments.

Journal Articles

A Scintillator-based detector with sub-100-$$mu$$m spatial resolution comprising a fibre-optic taper with wavelength-shifting fibre readout for time-of-flight neutron imaging

Nakamura, Tatsuya; To, Kentaro; Kawasaki, Takuro; Honda, Katsunori; Suzuki, Hiroyuki; Ebine, Masumi; Birumachi, Atsushi; Sakasai, Kaoru; Soyama, Kazuhiko; Katagiri, Masaki*

Nuclear Instruments and Methods in Physics Research A, 737, p.176 - 183, 2014/02

 Times Cited Count:10 Percentile:31.21(Instruments & Instrumentation)

Journal Articles

Detector system of the $$SENJU$$ single-crystal time-of-flight neutron diffractometer at J-PARC/MLF

Kawasaki, Takuro; Nakamura, Tatsuya; To, Kentaro; Hosoya, Takaaki*; Oikawa, Kenichi; Ohara, Takashi; Kiyanagi, Ryoji; Ebine, Masumi; Birumachi, Atsushi; Sakasai, Kaoru; et al.

Nuclear Instruments and Methods in Physics Research A, 735, p.444 - 451, 2014/01

 Times Cited Count:15 Percentile:17.29(Instruments & Instrumentation)

Journal Articles

Neutron diffraction study on the Xe behavior in clathrate hydrate analyzed by Rietveld/maximum entropy method

Igawa, Naoki; Taguchi, Tomitsugu; Hoshikawa, Akinori*; Yamauchi, Hiroki; Birumachi, Atsushi; Ishii, Yoshinobu*

IOP Conference Series; Materials Science and Engineering, 18, p.022021_1 - 022021_4, 2011/05

The neutron scattering length density distributions of Xe deuterohydrate were analyzed by Rietveld and MEM analysis applied to neutron powder diffraction data to clarify the Xe behavior in the temperature range from 10 to 245 K. A spherical positive scattering length density attributed to the Xe atom was observed at the center of the small cage of the hydrate. On the other hand, an ellipsoid shaped scattering length density distribution at the center of the large cage was observed; the major axis of the ellipsoid scattering length density was directed toward the center of a hexagonal facet of the large cage. The distributions of the Xe atom in the both cages were almost the same at any temperature.

Journal Articles

Wavelength-shifting-fibre-based neutron image detector with a fibre-optic taper to increase the spatial resolution

Nakamura, Tatsuya; Katagiri, Masaki; To, Kentaro; Sakasai, Kaoru; Ebine, Masumi; Birumachi, Atsushi; Soyama, Kazuhiko

Nuclear Instruments and Methods in Physics Research A, 604(1-2), p.158 - 160, 2009/06

 Times Cited Count:6 Percentile:53.78(Instruments & Instrumentation)

The effective pixel size of a two-dimensional wavelength-shifting-fibre (WLS-fibre)-based neutron image detector was improved from 0.5 to 0.16 mm by including a fibre-optic taper (FOT) between the scintillator screen and the WLS fibre. The WLS-fibre-based detector consisted of a thin ZnS/$$^{6}$$LiF screen, a FOT and WLS ribbons crossed in the x and y directions. The demonstrator detector had 16 fibre channels in each direction, and the light signals in each fibre were read out individually. The FOT was constructed from fine glass fibres with a taper ratio of 3.1, and served as an image magnifier. The prototype detector equipped with the FOT exhibited a spatial resolution of 0.3 mm, compared to the spatial resolution of 0.8 mm for the original detector without the FOT.

JAEA Reports

Development for upgrading Japanese ENGIN-X type linear scintillation neutron detectors; Development of new ZnS scintillator, light reflector and digital signal processing module

Nakamura, Tatsuya; Katagiri, Masaki; Birumachi, Atsushi; Ebine, Masumi; Tsutsui, Noriaki*; Soyama, Kazuhiko; Schooneveld, E. M.*; Rhodes, N. J.*

JAEA-Research 2008-116, 26 Pages, 2009/03

JAEA-Research-2008-116.pdf:4.25MB

New ZnS scintillator, light reflector and digital signal processing modules were developed to upgrade the Japanese ENGIN-X type linear scintillation neutron detector. The developed ZnS/$$^{10}$$B$$_{2}$$O$$_{3}$$ scintillator improved detector efficiency by a factor 1.2 for neutrons with a wavelength of 1 ${AA}$ whilst the detector maintained similar $$gamma$$ sensitivity and multi-count ratio compared to the present AST (4:1) scintillator. The paint coating less light reflector was developed with an aluminum reflector with etched surface. The detector implemented with this reflector exhibited similar detector performances with paint coating reflectors, confirming feasibility of the reflector with long-term stability. The digital signal-processing module incorporating photon-counting method was successfully developed. The fully digitalized photon counting system improved a temperature stability of neutron counts significantly comparing to the present analogue system.

JAEA Reports

Development of two-dimensional scintillator neutron detector using wavelength-shifting fibres; Development of a compact detector for iBIX instrument in J-PARC/MLF

Nakamura, Tatsuya; Katagiri, Masaki; Hosoya, Takaaki*; Birumachi, Atsushi; Ebine, Masumi; Soyama, Kazuhiko; Schooneveld, E.*; Rhodes, N.*

JAEA-Research 2008-115, 33 Pages, 2009/03

JAEA-Research-2008-115.pdf:3.77MB

A compact two-dimensional neutron detector was developed for iBIX instrument in the J-PARC/MLF. The specifications required for the detector were a spatial resolution of less than 1 mm, a detector efficiency of more than 50% for thermal neutrons, a $$gamma$$ sensitivity of less than 10$$^{6}$$, detector coverage of around 15$$times$$15 cm$$^{2}$$ with least dead area, compactness, modularity, and a pulse pair resolution of less than 2 $$mu$$s. The detector components were studied in detail and optimized for the purpose. The compact prototype detector that has a neutron sensitive area of 13.3$$times$$13.3 cm$$^{2}$$ was made and feasibility of the detector was demonstrated successfully in the experiments at the ISIS pulsed neutron source.

Journal Articles

Performance of semiconductor radiation sensors for simple and low-cost radiation detector

Tanimura, Yoshihiko; Birumachi, Atsushi; Yoshida, Makoto; Watanabe, Tamaki*

Radioisotopes, 57(12), p.733 - 738, 2008/12

In order to develop simple but reliable radiation meters for the general public, photon detection performances of radiation sensors have been studied both experimentally in photon calibration fields and by Monte Carlo simulations. A silicon $$_{it p-i-n}$$ photodiode and a CdTe detector were selected for the low-cost sensors. Their energy responses to ambient dose equivalent H$$^*$$(10) were evaluated over the energy range from 60 keV to 2 MeV. The response of the CdTe decreases markedly with increasing photon energy. On the other hand, the photodiode has the advantage of almost flat response above 150 keV. The sensitivities of these sensors are 4 to 6 cpm for the natural radiation. Detection limits of the radiation level are low enough to know the extreme increase of radiation due to emergency situations of nuclear power plants, fuel treatment facilities and so on.

JAEA Reports

Performance test of the Japanese ENGIN-X type linear scintillation neutron detector

Nakamura, Tatsuya; Sakasai, Kaoru; Katagiri, Masaki; Birumachi, Atsushi; Hosoya, Takaaki; Soyama, Kazuhiko; Sato, Setsuo*; Shooneveld, E.*; Rhodes, N.*

JAEA-Research 2007-014, 14 Pages, 2007/03

JAEA-Research-2007-014.pdf:1.9MB

The ENGIN-X type linear scintillation neutron detector was manufactured in Japan and the detector performances were evaluated. The ENGIN-X type linear scintillation neutron detector was originally developed by the detector group in Rutherford Appleton Laboratory and the Japanese prototype detector was identical to that which is one of the detector modules installed in the ENGIN-X diffractometer at ISIS pulsed neutron source. The prototype detector can install 240 elements of neutron-sensitive scintillator, where each element has 3 mm in width and 196 mm in length. The prototype detector exhibited a spatial resolution of 3 mm, detection efficiency of 64% for neutrons with wave-lengths of 1.8${AA}$, count uniformity of 6$$sim$$7%, $$^{60}$$Co $$gamma$$ sensitivity of $$sim$$5$$times$$10$$^{-7}$$. Technological transfer to the Japanese manufacturer was done successfully and the mass production of these detectors for the J-PARC project is feasible.

Journal Articles

Signal processing system based on FPGAs for neutron imaging detectors using scintillators

Ebine, Masumi; Katagiri, Masaki; Birumachi, Atsushi; Matsubayashi, Masahito; Sakasai, Kaoru; Sato, Setsuo*

Nuclear Instruments and Methods in Physics Research A, 529(1-3), p.429 - 432, 2004/08

 Times Cited Count:1 Percentile:89.17(Instruments & Instrumentation)

no abstracts in English

Journal Articles

A Compact neutron detector using scintillators with wavelength shifting fibers by backside readout method

Katagiri, Masaki; Matsubayashi, Masahito; Sakasai, Kaoru; Nakamura, Tatsuya; Ebine, Masumi; Birumachi, Atsushi; Rhodes, N.*

Nuclear Instruments and Methods in Physics Research A, 529(1-3), p.313 - 316, 2004/08

 Times Cited Count:11 Percentile:38.07(Instruments & Instrumentation)

no abstracts in English

Journal Articles

High counting rate two-dimensional neutron imaging method using rectangular scintillators with WLS fibers

To, Kentaro; Katagiri, Masaki; Sakasai, Kaoru; Matsubayashi, Masahito; Birumachi, Atsushi; Takahashi, Hiroyuki*; Nakazawa, Masaharu*

Applied Physics A, 74(Suppl.1), p.S1601 - S1603, 2002/12

 Times Cited Count:5 Percentile:74.53(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

High position-resolution scintillation neutron-imaging detector by crossed-fiber readout with novel centroid finding method

Katagiri, Masaki; To, Kentaro; Sakasai, Kaoru; Matsubayashi, Masahito; Birumachi, Atsushi; Takahashi, Hiroyuki*; Nakazawa, Masaharu*

Applied Physics A, 74(Suppl.1), p.S1604 - S1606, 2002/12

 Times Cited Count:5 Percentile:74.53(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Two-dimensional neutron imaging method using scintillators with wavelength shifting fibers

To, Kentaro; Katagiri, Masaki; Sakasai, Kaoru; Matsubayashi, Masahito; Birumachi, Atsushi; Takahashi, Hiroyuki*; Nakazawa, Masaharu*

Nuclear Instruments and Methods in Physics Research A, 485(3), p.571 - 575, 2002/09

 Times Cited Count:2 Percentile:79.91(Instruments & Instrumentation)

no abstracts in English

JAEA Reports

Development of Ge $$gamma$$ ray detector system for radioactivity measurement in deep sea

Yamamoto, Tadatoshi; Shimizu, Toku; Kozawa, Teruo; Birumachi, Atsushi; ; Katagiri, Masaki

JAERI-Research 99-032, 59 Pages, 1999/04

JAERI-Research-99-032.pdf:6.47MB

no abstracts in English

Oral presentation

Development of scintillator based neutron detectors for intense pulsed neutrons, 1; Fabrication of ISIS-type one-dimensional neutron detector and its operational test

Sakasai, Kaoru; Katagiri, Masaki; Nakamura, Tatsuya; Soyama, Kazuhiko; Birumachi, Atsushi; Sato, Setsuo*; Rhodes, N.*

no journal, , 

no abstracts in English

Oral presentation

Development of scintillator based neutron detectors for intense pulsed neutrons, 2; Development of digital signal processing method for ISIS-type 1D neutron detector

Ebine, Masumi; Katagiri, Masaki; Birumachi, Atsushi; Sakasai, Kaoru; Nakamura, Tatsuya; Soyama, Kazuhiko; Sato, Setsuo*; Schooneveld, E.*; Rohdes, N.*

no journal, , 

no abstracts in English

67 (Records 1-20 displayed on this page)