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Journal Articles

Background issues encountered by cold-neutron chopper spectrometer AMATERAS

Kikuchi, Tatsuya*; Nakajima, Kenji; Kawamura, Seiko; Inamura, Yasuhiro; Nakamura, Mitsutaka; Wakai, Daisuke*; Aoyama, Kazuhiro*; Iwahashi, Takaaki*; Kambara, Wataru*

Physica B; Condensed Matter, 564, p.45 - 53, 2019/07

 Times Cited Count:0 Percentile:100(Physics, Condensed Matter)

Details of the background, that is, unwanted signals accumulated by the data acquisition system of neutron instruments, observed by the cold-neutron chopper spectrometer AMATERAS installed at the Materials and Life Science Experimental Facility at J-PARC are reported. In the design phase of AMATERAS, we carefully considered the achievement of high signal-to-noise ratio, and possible countermeasures were implemented. Actually, recent scientific outputs from AMATERAS indicates that the spectrometer is one of excellent neutron instruments with low background. In spite of that, in nine years of AMATERAS operation, we have encountered unwanted signals due to various reasons, including gamma-rays emitted at materials on or near the beam line including the sample itself, scattered neutrons from the beam line devices, air scattering, electronic noise in data acquisition system, cosmic rays, T0 burst, and other unknown sources. In this report, we discuss the background observed by AMATERAS, especially in the conditions of without samples, comprehensively. The possible sources of these signals and the countermeasures considered against the above sources are discussed, which may be helpful to those who are engaged in other existing or planned neutron-scattering instruments.

Journal Articles

Cryogenic sample environments shared at the MLF, J-PARC

Kawamura, Seiko; Takahashi, Ryuta*; Ishikado, Motoyuki*; Yamauchi, Yasuhiro*; Nakamura, Masatoshi*; Ouchi, Keiichi*; Kira, Hiroshi*; Kambara, Wataru*; Aoyama, Kazuhiro*; Sakaguchi, Yoshifumi*; et al.

Journal of Neutron Research, 21(1-2), p.17 - 22, 2019/05

The Cryogenics and Magnets group in the Sample Environment team is responsible for operation of cryostats and magnets for user's experiments at the MLF in J-PARC. We have introduced a top-loading $$^4$$He cryostat, a bottom-loading $$^3$$He cryostat, a dilution refrigerator insert and a superconducting magnet. The frequency of use of them dramatically becomes higher in these two years, as the beam power and the number of proposal increase. To respond such situation, we have made efforts to enhance performance of these equipment as follows. The $$^3$$He cryostat originally involves an operation software for automatic initial cooling down to the base temperature and automatic re-charge of $$^3$$He. Recently we made an additional program for automatic temperature control with only the sorb heater. Last year, a new outer vacuum chamber of the magnet with an oscillating radial collimator (ORC) was fabricated. The data quality was drastically improved by introducing this ORC so that the magnet can be used even for the inelastic neutron scattering experiments.

Journal Articles

Study on use of superconducting magnet and first inelastic neutron scattering experiment under magnetic field at 4SEASONS spectrometer

Kajimoto, Ryoichi; Ishikado, Motoyuki*; Kira, Hiroshi*; Kaneko, Koji; Nakamura, Mitsutaka; Kamazawa, Kazuya*; Inamura, Yasuhiro; Ikeuchi, Kazuhiko*; Iida, Kazuki*; Murai, Naoki; et al.

Physica B; Condensed Matter, 556, p.26 - 30, 2019/03

 Times Cited Count:2 Percentile:51.08(Physics, Condensed Matter)

Journal Articles

Performances of oscillating radial collimator for the Fermi chopper spectrometer 4SEASONS at J-PARC

Nakamura, Mitsutaka; Kambara, Wataru*; Iida, Kazuki*; Kajimoto, Ryoichi; Kamazawa, Kazuya*; Ikeuchi, Kazuhiko*; Ishikado, Motoyuki*; Aoyama, Kazuhiro*

Physica B; Condensed Matter, 551, p.480 - 483, 2018/12

 Times Cited Count:1 Percentile:86.03(Physics, Condensed Matter)

Recently there has been an increasing need for inelastic neutron scattering experiments under some special environments such as magnetic fields, pressure and high temperatures. In order to obtain high quality data, the unnecessary scattering caused by sample environmental apparatus should be suppressed as much as possible. We have developed an oscillating radial collimator with a view to satisfying users' needs, which is specialized for the Fermi chopper spectrometer 4SEASONS at J-PARC.4SEASONS provides relatively high incident energies, and thus we chose hydrogen free metal sheets as the collimator blades. The control system of this oscillating radial collimator enables us to flexibly tune the oscillating pattern, such as the oscillating speed and oscillating angle. In this presentation, we report the performances and remaining issues of the newly developed oscillating radial collimator for 4SEASONS.

Journal Articles

Recent issues encountered by AMATERAS; A Cold-neutron disk-chopper spectrometer

Nakajima, Kenji; Kawamura, Seiko; Kikuchi, Tatsuya*; Kofu, Maiko; Kawakita, Yukinobu; Inamura, Yasuhiro; Kambara, Wataru*; Aoyama, Kazuhiro*; Wakai, Daisuke*; Harada, Masahide; et al.

Journal of Physics; Conference Series, 1021(1), p.012031_1 - 012031_5, 2018/06

 Times Cited Count:3 Percentile:4.08

Journal Articles

Recent progress in the chopper spectrometer 4SEASONS at J-PARC

Kajimoto, Ryoichi; Nakamura, Mitsutaka; Inamura, Yasuhiro; Kamazawa, Kazuya*; Ikeuchi, Kazuhiko*; Iida, Kazuki*; Ishikado, Motoyuki*; Nakajima, Kenji; Kawamura, Seiko; Nakatani, Takeshi; et al.

JAEA-Conf 2015-002, p.319 - 329, 2016/02

Journal Articles

Oscillating radial collimators for the chopper spectrometers at MLF in J-PARC

Nakamura, Mitsutaka; Kawakita, Yukinobu; Kambara, Wataru; Aoyama, Kazuhiro; Kajimoto, Ryoichi; Nakajima, Kenji; Kawamura, Seiko; Ikeuchi, Kazuhiko*; Kikuchi, Tatsuya; Inamura, Yasuhiro; et al.

JPS Conference Proceedings (Internet), 8, p.036011_1 - 036011_6, 2015/09

The needs for inelastic neutron scattering experiments under the special sample environment such as strong magnetic field and high temperature are recently increasing. However, the unwanted scatterings originating from these devices affect the detection of weak inelastic signals. In order to overcome this problem we have developed an oscillating radial collimator specialized for the chopper spectrometer at Materials and Life Science Experimental Facility (MLF) in J-PARC. In this study, we will report the performances of newly-developed oscillating radial collimators both for 4SEASONS and AMATERAS.

Journal Articles

Factors controlling the spatiotemporal variation of $$^{137}$$Cs in seabed sediment off the Fukushima coast; Implications from numerical simulations

Misumi, Kazuhiro*; Tsumune, Daisuke*; Tsubono, Takaki*; Tateda, Yutaka*; Aoyama, Michio*; Kobayashi, Takuya; Hirose, Katsumi*

Journal of Environmental Radioactivity, 136, p.218 - 228, 2014/10

 Times Cited Count:17 Percentile:38.28(Environmental Sciences)

Major controls on spatiotemporal variations of $$^{137}$$Cs activity in seabed sediments derived from the Fukushima Dai-ichi Nuclear Power Plant accident during the first year after the accident were investigated by using numerical simulations. The model successfully reproduced major features of the observed spatiotemporal variations of $$^{137}$$Cs activity in sediments. The spatial pattern of $$^{137}$$Cs in sediments, which mainly reflected the history of $$^{137}$$Cs activity in the bottom water overlying the sediment and the sediment particle size distribution, became established during the first several months after the accident. Taking $$^{137}$$Cs activities in sediments in the coastal area and in the vicinity of the power plant into account, increased the simulated total inventory of $$^{137}$$Cs in sediments off the Fukushima coast to a value on the order of 10$$^{14}$$ Bq.

JAEA Reports

Fuel Failure Simulation Test in JOYO; FFDL in-pile test(III)

Ito, Chikara; Ito, Hideaki; Ishida, Koichi; Hatoori, Kazuhiro; Oyama, Kazuhiro; Sukegawa, Kazuya*; Murakami, Takanori; Kaito, Yasuaki; Nishino, Kazunari; Aoyama, Takafumi; et al.

JNC-TN9410 2005-003, 165 Pages, 2005/03

JNC-TN9410-2005-003.pdf:12.66MB

At experimental fast reactor JOYO, appraisal of detection efficiency of behavior and FFD and FFDL of the fission product which is discharged inside the furnace as one of safety research of the country, is carried out. In MK-II core, the slit in the gas plenum part of the test sub-assembly, the test which irradiates this(1985 April, FFDL in-pile test(I)), providing the slit in the fuel column part of the test sub-assembly, the test which it irradiates(1992 November, FFDL in-pile test(II)) were carried out.MK-III reactor core replacement was completed and started in 2004. That the behavior in the system of FP with the reactor core replacement and so on changes in the MK-III reactor core and to have an influence on the sensitivity and the replying of FFD and FFDL are thought of. Therefore, behavior of FP in the fuel failure in the MK-III reactor core, the performance of FFD and FFDL must be confirmed beforehand. Moreover, to prepare for the fuel failure and the RTCB test which is doing a future plan, and to confirm a plant operation procedure in the fuel failure in MK-III reactor core operation and to attempt for the correspondency to improve are important.Therefore, in the period from 2004 November 11th to November 29th, it carried out the FFDL in-pile(III). It did a series of plant operation to stop a nuclear reactor after loading a reactor core center with the fuel element for the test which provided an artificial slit for the fuel cladding in the MK-III reactor core and irradiating it and detecting fuel damaging and to take out fuel. And it confirmed the operation procedure of the fast reactor in the fuel failure.Also, the improvement items such as the improvement of the operation and the procedure and the remodeling and the service of the facilities could be picked up. In the future, it attempts these compatible, and it prepares for the MK-III reactor core operation and it incorporates a final examination result by the improvement of the safety of FBR.

JAEA Reports

Summary Report of the Experimental Fast Rector JOYO MK-III Performance Test

Maeda, Yukimoto; Aoyama, Takafumi; Yoshida, Akihiro; Sekine, Takashi; Ariyoshi, Masahiko; Ito, Chikara; Masaaki, Nemoto; Murakami, Takanori; Isozaki, Kazunori; Hoshiba, Hideaki; et al.

JNC-TN9410 2003-011, 197 Pages, 2004/03

JNC-TN9410-2003-011.pdf:10.26MB

MK-III performance tests began in June 2003 to fully characterize the upgraded core and heat transfer system. Then, the last pre-use inspection was finished in November 2003.This report summarize the result of each performance test.

JAEA Reports

JOYO-CEFR Technical Information Exchange Meeting

Oyama, Kazuhiro; Aoyama, Takafumi

JNC-TN9200 2003-005, 175 Pages, 2004/03

JNC-TN9200-2003-005.pdf:17.64MB

On 2004 February 26th it hosted the conference which does a communication about the current status and the technical development,etc of JOYO , CEFR and MONJU.Through the meeting, a discussion was done for the information exchange meeting and the mutual sending of the technical expert as the cooperation of the future. We were possible to confirm about the field to be interested in CEFR.

Oral presentation

Failed fuel detection and location in a fast reactor by fission product gas analysis with laser resonance ionization mass spectrometry

Ito, Chikara; Hattori, Kazuhiro; Aoyama, Takafumi; Arima, Toshihiro*

no journal, , 

no abstracts in English

Oral presentation

Performance evaluation test of radial collimators for chopper spectrometer at J-PARC

Nakamura, Mitsutaka; Kawakita, Yukinobu; Kambara, Wataru; Aoyama, Kazuhiro; Yamauchi, Yasuhiro; Kajimoto, Ryoichi; Ikeuchi, Kazuhiko*; Iida, Kazuki*; Inamura, Yasuhiro; Nakajima, Kenji; et al.

no journal, , 

In recent years, the need for neutron inelastic scattering experiments in special environments under the strong magnetic field and the high temperature is increasing. On the other hand, there is a problem that the unnecessary scattering originating from the sample environment devices affects the detection of weak inelastic signals. To solve this problem, we have been developing the radial collimator for chopper spectrometer at J-PARC. In this talk, we plan to introduce the performance evaluation results of our radial collimator.

Oral presentation

The Chopper spectrometer BL01-4SEASONS at J-PARC '13

Kajimoto, Ryoichi; Nakamura, Mitsutaka; Inamura, Yasuhiro; Ikeuchi, Kazuhiko*; Iida, Kazuki*; Ishikado, Motoyuki*; Suzuki, Junichi*; Nakajima, Kenji; Kawamura, Seiko; Nakatani, Takeshi; et al.

no journal, , 

no abstracts in English

Oral presentation

Development of radial collimators for chopper spectrometer at J-PARC

Nakamura, Mitsutaka; Kawakita, Yukinobu; Kambara, Wataru; Yamauchi, Yasuhiro; Aoyama, Kazuhiro; Kajimoto, Ryoichi; Ikeuchi, Kazuhiko*; Iida, Kazuki*; Inamura, Yasuhiro; Nakajima, Kenji; et al.

no journal, , 

Recently, there is a growing need for neutron inelastic scattering experiments under special sample environments such as strong magnetic field and high temperatures. However the unwanted scattering originating from the sample environment equipment adversely affect the detection of weak inelastic signal. In order to overcome these difficulties, we have developed the radial collimators for chopper spectrometers at J-PARC. In this report we will show the results of performance evaluation tests for radial collimators.

Oral presentation

Chopper-type Neutron Spectrometer 4SEASONS on BL01 in MLF, J-PARC

Kajimoto, Ryoichi; Nakamura, Mitsutaka; Inamura, Yasuhiro; Kamazawa, Kazuya*; Ikeuchi, Kazuhiko*; Iida, Kazuki*; Ishikado, Motoyuki*; Suzuki, Junichi*; Nakajima, Kenji; Kawamura, Seiko; et al.

no journal, , 

no abstracts in English

Oral presentation

Recent status of a cold neutron disk chopper spectrometer AMATERAS

Nakajima, Kenji; Kawamura, Seiko; Kikuchi, Tatsuya; Kawakita, Yukinobu; Inamura, Yasuhiro; Kajimoto, Ryoichi; Nakamura, Mitsutaka; Soyama, Kazuhiko; Harada, Masahide; Oikawa, Kenichi; et al.

no journal, , 

Oral presentation

Development of various shielding devices to suppress background in J-PARC

Kambara, Wataru; Aoyama, Kazuhiro; Yamauchi, Yasuhiro; Iwahashi, Takaaki; Ono, Shino; Kajimoto, Ryoichi; Nakamura, Mitsutaka; Shibata, Kaoru; Nakajima, Kenji; Kawamura, Seiko; et al.

no journal, , 

Oral presentation

The Chopper spectrometer BL01-4SEASONS at J-PARC '14

Kajimoto, Ryoichi; Nakamura, Mitsutaka; Inamura, Yasuhiro; Kamazawa, Kazuya*; Ikeuchi, Kazuhiko*; Iida, Kazuki*; Ishikado, Motoyuki*; Nakajima, Kenji; Kawamura, Seiko; Nakatani, Takeshi; et al.

no journal, , 

no abstracts in English

Oral presentation

A Cold-neutron disk-chopper spectrometer AMATERAS in JFY2014

Nakajima, Kenji; Kawamura, Seiko; Kikuchi, Tatsuya; Inamura, Yasuhiro; Kawakita, Yukinobu; Kajimoto, Ryoichi; Nakamura, Mitsutaka; Soyama, Kazuhiko; Arai, Masatoshi; Aoyama, Kazuhiro; et al.

no journal, , 

no abstracts in English

29 (Records 1-20 displayed on this page)