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Nakamura, Tatsuya; Kawasaki, Takuro; To, Kentaro; Harjo, S.; Sakasai, Kaoru; Aizawa, Kazuya
JPS Conference Proceedings (Internet), 33, p.011097_1 - 011097_6, 2021/03
A large area, two-dimensional scintillation neutron detector was developed for Takumi diffractometer in the J-PARC MLF. The detector is made based on a scintillator/wavelength shifting fiber technology. The detector has a neutron-sensitive area of 32 
32 cm with a pixel size of 5 5 mm, which is about 1.5-fold larger than the SENJU detector TAKUMI is one of the neutron diffractometers in the MLF dedicated to use for engineering material research. The developed detector array adds new capabilities to the instrument to measure two-dimensional data collection at the back-scattering angles with a better time-of-flight resolution.
Maekawa, Fujio
JPS Conference Proceedings (Internet), 33, p.011042_1 - 011042_6, 2021/03
Development of beam window (BW) materials is one of crucial issues in development of accelerator driven nuclear transmutation systems (ADS). The BW is exposed to high energy protons and spallation neutrons, and also to corrosive lead-bismuth eutectic (LBE) alloy at high temperature of about 500
C. Recently, not only high-power accelerators but also high-power targets are the rate-limiting factor for increasing the power of accelerator facilities in terms of radiation damage and heat removal. To study radiation damage on BW and target materials for high-power accelerator facilities including ADS, we are planning a materials irradiation facility by utilizing the proton beam of 400 MeV and 250 kW provided by the J-PARC's Linac. The target is flowing LBE alloy which is a candidate target and coolant material of ADS. When a steel sample is irradiated in the target for one year, the sample receives radiation damage of about 10 dpa at maximum which is equivalent to the yearly radiation damage of ADS's BW. In the current facility concept, the facility is equipped with a hot-laboratory for efficient post-irradiation examination. The facility will be outlined in this presentation.
Harada, Hiroyuki; Hayashi, Naoki
JPS Conference Proceedings (Internet), 33, p.011027_1 - 011027_6, 2021/03
The transverse betatron tune is one of the most important key parameters in a ring accelerator because emittance growth and beam loss occur directly in case of crossing a betatron resonance. Especially, the tune must be required a controll with high accuracy in high intensity proton accelerator from the view point of space charge force and the beam instability. In general measurement method, the betatron tune is measured by analyzing the detected beam oscillation on Fourier transform. However, the beam is quickly accelerated and the revolution frequency of the beam changes quickly in a rapid cycling synchrotron. So, the tune accuracy is not improved. A new method was developed for high resolution analysis of the tune and was evaluated in J-PARC accelerator. Tune accuracy was successfully improved from 0.013 to less than 0.001. Tune controll with high accuracy is base for high-intensity beam. In this paper, the new method is introduced and the measured result in J-PARC is report.
beam with 3 MeV by the bunch-shape monitorKitamura, Ryo; Futatsukawa, Kenta*; Hayashi, Naoki; Hirano, Koichiro; Kondo, Yasuhiro; Kosaka, Satoshi*; Miyao, Tomoaki*; Nemoto, Yasuo*; Morishita, Takatoshi; Oguri, Hidetomo
JPS Conference Proceedings (Internet), 33, p.011012_1 - 011012_6, 2021/03
The new bunch shape monitor (BSM) is required to measure the bunch size of the high-intensity H beam with 3 MeV at the front-end section in the J-PARC linac. The carbon-nano tube wire and the graphene stick are good candidates for the target wire of the BSM, because these materials have the enough strength to detect the high-intensity beam. However, since the negative high voltage of more than a few kV should be applied to the wire in the BSM, the suppression of the discharge is the challenge to realize the new BSM. After the high-voltage test to investigate the effect of the discharge from the wire, the detection of the signal from the BSM was successful at the beam core with the peak current of 55 mA using the graphene stick. The preliminary result of the bunch-size measurement is reported in this presentation.
Abe, Yuta; Tsuchikawa, Yusuke; Kai, Tetsuya; Matsumoto, Yoshihiro*; Parker, J. D.*; Shinohara, Takenao; Oishi, Yuji*; Kamiyama, Takashi*; Nagae, Yuji; Sato, Ikken
JPS Conference Proceedings (Internet), 33, p.011075_1 - 011075_6, 2021/03
Oikawa, Kenichi; Harjo, S.; Pham, A. H.*; Kawasaki, Takuro; Morito, Shigekazu*; Kiyanagi, Yoshiaki*; Shinohara, Takenao; Kai, Tetsuya; Oba, Takuya*; Ito, Masakazu*
JPS Conference Proceedings (Internet), 33, p.011062_1 - 011062_6, 2021/03
-P column by neutron resonance absorption imagingMiyazaki, Yasunori; Watanabe, So; Nakamura, Masahiro; Shibata, Atsuhiro; Nomura, Kazunori; Kai, Tetsuya; Parker, J. D.*
JPS Conference Proceedings (Internet), 33, p.011073_1 - 011073_7, 2021/03
Neutron resonance absorption imaging was adapted to observe the Eu band adsorbed in the CMPO/SiO-P column for minor actinide recovery by extraction chromatography. Several wet columns were prepared by either light water or heavy water and compared with the dry column to evaluate the neutron transmission. The neutron transmission spectra showed that 45% was transmitted through the dry column while 20% and 40% were transmitted through the wet columns of light water and heavy water, respectively. The results indicated that heavy water is more applicable than light water to observe the Eu adsorption band in the CMPO/SiO-P column.
Harada, Hiroyuki; Saha, P. K.; Yoneda, Hitoki*; Michine, Yurina*; Fuchi, Aoi*; Sato, Atsushi*; Kinsho, Michikazu
JPS Conference Proceedings (Internet), 33, p.011026_1 - 011026_6, 2021/03
The charge-exchange multi-turn injection by using a carbon stripper foil is adopted in high-intensity proton ring accelerators worldwide. It is a beneficial method to compress the pulsed proton beam with high intensity but there are serious issues for high intensity. First issue is a short lifetime of the foil by deformation or breaking itself. Another issue is high radiation dose corresponding to the scattered particles on the foil. Therefore, a non-destructive stripping injection method is required for higher intensity proton beam. We newly propose a non-destructive method of H stripping by using only laser. The new method is called "laser stripping injection". To establish our method, we are preparing for a POP (Proof-of-Principle) experiment of 400 MeV H- stripping to proton at J-PARC. In our presentation we will present the current status of laser system development for laser stripping injection at J-PARC.
ion sourceOguri, Hidetomo; Okoshi, Kiyonori; Shinto, Katsuhiro; Shibata, Takanori*; Nammo, Kesao*; Ikegami, Kiyoshi*; Takagi, Akira*; Ueno, Akira
JPS Conference Proceedings (Internet), 33, p.011008_1 - 011008_7, 2021/03
A cesiated RF-driven negative hydrogen ion source was initiated to operate in September, 2014 in response to the need for upgrading J-PARC's linac beam current. The ion source mainly comprises a stainless-steel plasma chamber, a beam extractor and a large vacuum chamber equipped with two turbo molecular pumps, each having the pumping speed of 1500 L/s, for differential pumping. The user operation was started with the beam current of 33 mA from the ion source. We gradually increased both beam current and continuous operation time of the ion source. In July, 2018 (Run#79), approximately 2,200 hours operation was achieved with the typical beam current, pulse length and repetition rate of 47 mA, 300 
s and 25 Hz, respectively. Since October, 2018 (Run#80), the ion source has been delivering a nominal beam current of approximately 60 mA.
Iwamoto, Hiroki; Meigo, Shinichiro
JPS Conference Proceedings (Internet), 33, p.011046_1 - 011046_6, 2021/03
no abstracts in English
Sakai, Kenji; Oi, Motoki; Haga, Katsuhiro; Kai, Tetsuya; Nakatani, Takeshi; Kobayashi, Yasuo*; Watanabe, Akihiko*
JPS Conference Proceedings (Internet), 33, p.011151_1 - 011151_6, 2021/03
For safely and efficiently operating a spallation neutron source and a muon target, a general control system (GCS) operates within Materials and Life Science Experimental Facility (MLF), GCS administers operation processes and interlocks of many instruments for various operation statuses. It consists of several subsystems such as an integral control system (ICS), interlock systems (ILS), shared servers, network system, and timing distribution system (TDS). Although GCS is an independent system that controls the target stations, it works closely with the control systems of other facilities in J-PARC. Since the first beam injection in 2008, GCS has operated stably without any serious troubles after modification based on commissioning for operation and control. Then, significant improvements in GCS such as upgrade of ICS by changing its framework software and function enhancement of ILS were proceeded until 2015, in considering sustainable long-term operation and maintenance. In recent years, many instruments in GCS have replaced due to end of production and support of them. In this way, many modifications have been proceeded in the entire GCS after start of beam operation. Under these situation, it is important to comprehend upgrade history and present status of GCS in order to decide its upgrade plan for the coming ten years. This report will mention upgrade history, present status and future agenda of GCS.
Sakai, Kenji; Oku, Takayuki; Okudaira, Takuya; Kai, Tetsuya; Harada, Masahide; Hiroi, Kosuke; Hayashida, Hirotoshi*; Kakurai, Kazuhisa*; Shimizu, Hirohiko*; Hirota, Katsuya*; et al.
JPS Conference Proceedings (Internet), 33, p.011116_1 - 011116_6, 2021/03
In neutron fundamental physics, study of correlation term 
of a neutron spin 
and a target nuclear spin 
is important because term interferes to parity non-conserving (PNC) and time reversal non-conserving terms. For this study, a xenon (Xe) is an interesting nucleus because it has been observed an enhancement of PNC effect around neutron resonance peaks, and polarizes up to 
by using a spin exchange optical pumping (SEOP) method. We would plan to develop a polarized Xe gas target with a compact in-situ SEOP system, and to study term by utilizing epithermal neutron beams supplied from a high intense pulsed spallation neutron source. As the first step, we attempted to measure neutron polarizing ability caused by term at a 9.6 eV s-wave resonance peak of 
Xe at BL10 in MLF, by detecting change 
of ratio between neutron transmissions with the polarized and unpolarized Xe target. After demonstrating that our apparatus could detect small change (
) of neutron transmissions caused by Doppler broadening effect, a signified value of has been obtained as preliminary results. For analyzing the obtained in detail, we are improving our nuclear magnetic resonance and electron paramagnetic resonance systems for evaluating Xe polarization independently of neutron beams.
Harada, Masahide; Sekijima, Mitsuaki*; Morikawa, Noriyuki*; Masuda, Shiho; Kinoshita, Hidetaka; Sakai, Kenji; Kai, Tetsuya; Kasugai, Yoshimi; Muto, Giichi*; Suzuki, Akio*; et al.
JPS Conference Proceedings (Internet), 33, p.011099_1 - 011099_6, 2021/03
In MLF at J-PARC, a unified mercury radioactivity monitor (UHAM) is installed to find an indication of failure of the mercury target and loop system by detecting radioactive materials leaked from the system with a 
-ray energy analysis with Germanium semi-conductor detectors (Ge detectors). It is composed of three units of sampling port and radiation monitors: (1) HAM for interstitial helium gas layer between the mercury vessel and surrounding water shroud of the mercury target, (2) CAM for atmosphere in the hot cell where the target loop is operated and (3) VAM for helium gas in the helium vessel where the target vessel is installed. Once any leakages of radioactive materials are detected, an alarm signal is issued immediately to the accelerator control system to stop beam operation. Software and hardware have been upgraded yearly. For example, two Ge detectors are used for HAM for redundancy, NaI Scintillation detectors are also used as supplemental for the Ge detector to keep availability of the system for high counting rate event. In April 2015, the UHAM activated when a small water coolant leakage from the water shroud of the mercury target occurred. VAM detected an abnormal increase of the counting rate in the helium vessel. It was also indicated that the measured radioactive nuclides were generated from the activation of the coolant (water) in the water shroud and not from the mercury.
Yamamoto, Kazami; Hasegawa, Kazuo; Kinsho, Michikazu; Oguri, Hidetomo; Hayashi, Naoki; Yamazaki, Yoshio; Naito, Fujio*; Yoshii, Masahito*; Toyama, Takeshi*
JPS Conference Proceedings (Internet), 33, p.011016_1 - 011016_7, 2021/03
The Japan Proton Accelerator Research Complex (J-PARC) is a multipurpose facility for scientific experiments. The accelerator complex consists of a 400-MeV Linac, a 3-GeV Rapid-Cycling Synchrotron (RCS) and a 30-GeV Main Ring synchrotron (MR). The RCS delivers a proton beam to the neutron target and MR, and the MR delivers the beams to the neutrino target and the Hadron Experimental Facility. The first operation of the neutron experiments began in December 2008. Following this, the user operation has been continued with some accidental suspensions. These suspensions include the recovery work due to the Great East Japan Earthquake in March 2011 and the radiation leak incident at the Hadron Experimental Facility. In this report, we summarize the major causes of suspension, and the statistics of the reliability of J-PARC accelerator system is analyzed. Owing to our efforts to achieve higher reliability, the Mean Time Between Failure (MTBF) has been improved.
Tsuchikawa, Yusuke; Abe, Yuta; Oishi, Yuji*; Kai, Tetsuya; Toh, Yosuke; Segawa, Mariko; Maeda, Makoto; Kimura, Atsushi; Nakamura, Shoji; Harada, Masahide; et al.
JPS Conference Proceedings (Internet), 33, p.011074_1 - 011074_6, 2021/03
In the decommissioning of the Fukushima-Daiichi (1F) Nuclear Power Plant, it is essential to understand characteristics of the melted core materials. The estimation of boride in the real debris is of great importance to develop safe debris removal plans. Hence, it is required to investigate the amount of boron in the melted core materials with nondestructive methods. Prompt gamma-ray activation analysis (PGAA) is one of the useful techniques to determine the amount of borides by means of the 478 keV prompt gamma-ray from neutron absorption reaction of boron. Moreover, it is well known that the width of the 478 keV gamma-ray peak is typically broadened due to the Doppler effect. The degree of the broadening is affected by coexisting materials, and can be recognized by the width of the prompt gamma-ray peak. As a feasibility study, the prompt gamma-ray from boride samples were measured using the ANNRI, NOBORU, and RADEN beamlines at the Materials and Life Science Experimental Facility (MLF) of Japan Proton Accelerator Complex (J-PARC).
Maruyama, Ryuji; Yamazaki, Dai; Akutsu, Kazuhiro*; Hanashima, Takayasu*; Miyata, Noboru*; Aoki, Hiroyuki; Soyama, Kazuhiko
JPS Conference Proceedings (Internet), 33, p.011092_1 - 011092_6, 2021/03
no abstracts in English
FeTiO
Kodama, Katsuaki; Honda, Takashi*; Ikeda, Kazutaka*; Shamoto, Shinichi; Otomo, Toshiya*
JPS Conference Proceedings (Internet), 33, p.011059_1 - 011059_6, 2021/03
Kasugai, Yoshimi; Sato, Koichi; Takahashi, Kazutoshi*; Miyamoto, Yukihiro; Kai, Tetsuya; Harada, Masahide; Haga, Katsuhiro; Takada, Hiroshi
JPS Conference Proceedings (Internet), 33, p.011144_1 - 011144_6, 2021/03
A spallation neutron source with a mercury target has been in operation at the Materials and Life Science Experimental Facility of J-PARC since 2008. The target vessel made of stainless steel is required to be exchanged periodically due to radiation damage etc. In this presentation, tritium gas release observed in the first series of exchange work in 2011 and the analytical results will be shown.
Mori, Kazuhiro*; Okumura, Ryo*; Yoshino, Hirofumi*; Kanayama, Masaya*; Sato, Setsuo*; Oba, Yojiro; Iwase, Kenji*; Hiraka, Haruhiro*; Hino, Masahiro*; Sano, Tadafumi*; et al.
JPS Conference Proceedings (Internet), 33, p.011093_1 - 011093_6, 2021/03
no abstracts in English
Kamiya, Junichiro; Kotoku, Hirofumi; Hikichi, Yusuke*; Takahashi, Hiroki; Yamamoto, Kazami; Kinsho, Michikazu; Wada, Kaoru*
JPS Conference Proceedings (Internet), 33, p.011023_1 - 011023_6, 2021/03
The vacuum system is the key for the stable high power beam operation in J-PARC 3 GeV rapid cycling synchrotron (RCS), because the gas molecules in the beam line make the beam loss due to the scattering. The more than 10 years operation of the RCS vacuum system showed that the ultra-high vacuum (UHV) has been stably maintained by the several developments. The challenges for lower beam line pressure will exist in a future operation with higher beam power. For such challenge, a TMP with a rotor of titanium alloy, which have much higher mechanical strength than aluminum allow for the normal rotter, has been developed. Overcoming the difficulties of the machining performance of the titanium alloy rotor was successfully manufactured. We will report the summary of the 10 years operation of the RCS vacuum system and the incoming developments towards the XHV.
