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Journal Articles

Applying neural networks to investigations of the influence of weather conditions on the power consumption of J-PARC

Nomura, Masahiro; Tamura, Fumihiko; Shimada, Taihei; Yamamoto, Masanobu; Furusawa, Masashi*; Sugiyama, Yasuyuki*; Hara, Keigo*; Hasegawa, Katsushi*; Omori, Chihiro*; Yoshii, Masahito*

Proceedings of 16th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.258 - 261, 2019/07

In recent years, summer temperatures have tended to increase, so understanding the amount of power consumption in summer from weather information has become important in terms of contract power and power saving measures. The relationship between the amount of power consumption and weather conditions is that the accelerator facility has many cooling facilities, so it can be thought that the amount of power used to cool each device increases as the temperature and humidity increase. It seems that it has not been investigated specifically what kind of dependence there is. Therefore, considering the neural network as a kind of fitting function or a model of calculation, we investigated the influence of weather conditions on the power consumption. As a result, it was found that the power consumption of the accelerators mostly depends only on the temperature, and the electric power of Linac and RCS increases by about 1 MW when the temperature of Mito rises by 10$$^{circ}$$C.

Journal Articles

The Residual dose distribution and worker doses in J-PARC 3GeV rapid cycling synchrotron

Yamamoto, Kazami

Proceedings of 16th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.333 - 337, 2019/07

J-PARC 3GeV Synchrotron (RCS) started beam commissioning in 2007. The beam commissioning has been continued to increase the beam power for users. In a high-intensity hadron accelerator such as J-PARC, it is essentially important to reduce the activation due to beam loss and to suppress the exposure of workers. For this purpose, RCS has continued to study and countermeasure for the causes of beam loss from the initial stage of beam commissioning. At present, stable user operation is continuing at 500 kW. This value is half the design beam power of 1 MW, and the residual doses are being maintained enough small so that the maintenance work does not be hindered. In this report, we will introduce the history and measures of the residual doses in RCS so far, and the situation of the exposure dose of workers during maintenance work.

Journal Articles

Development of the new method to utilize the titanium vacuum chamber as a vacuum pump

Kamiya, Junichiro; Hikichi, Yusuke*; Wada, Kaoru*

Proceedings of 16th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1189 - 1192, 2019/07

Non-evaporable getter (NEG) coating, which was developed at CERN, is the breakthrough method, which makes a beam pump a vacuum pump by coating a getter material on the beam pipe surface. The usage of the NEG coating has widely spread in the accelerators in recent years. On the other hand, J-PARC uses titanium, which is a low activation material, as a material for the beam pipe. If the titanium oxide on the surface can be removed, the titanium beam pip plays the role of the vacuum pump because the pure titanium is a getter material. In this presentation, we report on the method of oxide film removal by the sputtering method and vacuum performances of the titanium vacuum chamber as the getter pump.

Journal Articles

Fabrication status of charge stripper foil for 3 GeV synchrotron of J-PARC

Nakanoya, Takamitsu; Yoshimoto, Masahiro; Yamazaki, Yoshio; Takeda, Osamu*; Saeki, Riuji*; Muto, Masayoshi*

Proceedings of 16th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.545 - 549, 2019/07

In the 3 GeV Rapid Cycling Synchrotron (RCS) of the Japan Proton Accelerator Research complex (J-PARC), we adopted the carbon stripper foil for the multi-turn H- charge exchange injection. The charge exchange foil which use in RCS is fabricated by the arc discharge method with the boron doped carbon electrode. The foil fabricated this method is called HBC foil (Hybrid Boron mixed Carbon stripper foil). HBC foil had been developed at KEK. It has high durability for the beam irradiation damage. In past days, the foil fabrication process was conducted in KEK Tsukuba-site and the foil preparation process was conducted in JAEA Tokai-site. In 2017, the foil deposition apparatus has been relocated from KEK to JAEA, and we started both processes in Tokai-site. We carried out the offline beam irradiation test for the new HBC foil which fabricated in JAEA, and we confirmed that its performance is equivalent to the original HBC foil. Next we tested a new HBC foil with actual beam in RCS and we confirmed it could withstand 1 week beam irradiation. After that, we started user operation with the new HBC foil in 2018. So far we accomplished stable user operation for one year by using the new HBC foil only.

Journal Articles

Next generation timing system for J-PARC

Tamura, Fumihiko; Takahashi, Hiroki; Kamikubota, Norihiko*; Ito, Yuichi; Hayashi, Naoki

Proceedings of 16th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.149 - 152, 2019/07

Precise timing pulses from the timing system are necessary for acceleration of high intensity proton beams in the J-PARC accelerators. The existing timing system was developed during the construction period of the J-PARC. The system has been working well for more than ten years, however, the optical modules for the signal transfer from the central control building to the accelerators are discontinued already. Although we have spares of the optical devices, maintenance of the system will be difficult. Therefore, we are developing the next generation timing system for the J-PARC. We present the design of the system, preliminary test results, and future plans.

Journal Articles

Recent progress of the J-PARC RCS beam commissioning and operation; Efforts to realize a higher beam power beyond 1 MW

Hotchi, Hideaki; Harada, Hiroyuki; Hayashi, Naoki; Kinsho, Michikazu; Okabe, Kota; Saha, P. K.; Shobuda, Yoshihiro; Tamura, Fumihiko; Yamamoto, Kazami; Yamamoto, Masanobu; et al.

Proceedings of 16th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.574 - 578, 2019/07

no abstracts in English

Journal Articles

Present status of personnel protection system at J-PARC

Kikuzawa, Nobuhiro; Niki, Kazuaki*; Yamamoto, Noboru*; Hayashi, Naoki; Adachi, Masatoshi*; Watanabe, Kazuhiko*

Proceedings of 16th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.877 - 880, 2019/07

Interlock system of J-PARC is classified into a personnel protection system (PPS) for human safety and a machine protection system (MPS) for protecting equipment. The PPS of the J-PARC accelerator started from the operation at Linac in 2006 and was completed by the MR operation in 2008. In the next 10 years, some improvements have been made, such as updating video monitoring systems and establishing new interlocks. In addition to describing recent operations including these updatings, this paper reports the current status of inspections and maintenance conducted to maintain and improve reliability.

Journal Articles

Beam monitor data analysis of interlocked events at J-PARC RCS

Hayashi, Naoki; Yoshimoto, Masahiro; Moriya, Katsuhiro; Hatakeyama, Shuichiro*

Proceedings of 16th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1096 - 1100, 2019/07

It is necessary to understand the reason why the accelerator has been interrupted due to beam loss or other machine mal function in order to keep high availability in long term period. At J-PARC RCS, 25 Hz rapid-cycling synchrotron, there is a system to record beam intensity and beam loss monitor signal for all pulses with 10 ms period. At this time, in addition, new system to archive data with better time resolution if interlocked events occurred has been introduced. Using these archived data, the events only RCS BLM gives MPS have been analyzed and it turns out that these events are related to the ion source discharge which makes very low intensity within less than a second. In this paper other typical events are presented and discuss how to improve the accelerator performance in future.

Journal Articles

Development of two-mirror multi-pass laser system to reduce laser power for laser stripping injection at J-PARC 3-GeV RCS

Saha, P. K.; Harada, Hiroyuki; Kinsho, Michikazu; Sato, Atsushi*; Yoneda, Hitoki*; Michine, Yurina*

Proceedings of 16th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.841 - 845, 2019/07

Journal Articles

Investigation for tiny metal contamination of water cooling system in J-PARC Linac

Suganuma, Kazuaki; Hiroki, Fumio; Ito, Takashi; Yamazaki, Yoshio

Proceedings of 16th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.846 - 848, 2019/07

In the past, water flow decreased at water cooling system in J-PARC Linac. Contamination get mixed in cooling water. The problem was resolved by changing the system of the circulation pumps and reducing the tiny metal in water cooling system. However, suppression of occurring tiny metal is unresolved. The tiny metal is the unique problem of accelerator. It is caused by heavy using oxygen free copper and phosphorus deoxidized copper. The two copper is used for the part of accelerator and purified water. The object of the report is investigation of tiny metal contamination of water cooling system in J-PARC Linac.

Journal Articles

Present status of JAEA-Tokai tandem accelerator

Matsuda, Makoto; Osa, Akihiko; Ishizaki, Nobuhiro; Tayama, Hidekazu; Kabumoto, Hiroshi; Nakamura, Masahiko; Kutsukake, Kenichi; Otokawa, Yoshinori; Asozu, Takuhiro; Matsui, Yutaka; et al.

Proceedings of 16th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1270 - 1273, 2019/07

The JAEA-Tokai tandem accelerator was operated over a total of 138 days, and delivered 16 different ions to the experiments in the research fields of nuclear physics, nuclear chemistry, atomic physics, solid state physics and radiation effects in material in FY2018. Maximum acceleration voltage was 16.6 MV. A new beam attenuator was installed at the entrance beam line of the tandem accelerator to facilitate control of the beam current and minimize stripper foil consumption. The main maintenance items included replacing the pellet chain used for about 68,000 hours and the drive motor for the high voltage terminal generator used for about 9 years. A fault has occurred in the building's oxygen deficiency monitor. This paper describes the operational status of the accelerators and the major technical developments of our facility.

Journal Articles

Development of pulse power supply for kicker using power semiconductor and alternative switch for ignitron

Takayanagi, Tomohiro; Ono, Ayato; Ueno, Tomoaki*; Horino, Koki*; Yamamoto, Kazami; Kinsho, Michikazu

Proceedings of 16th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.75 - 79, 2019/07

We will replace the Thyratron and Ignitron discharge type switch with a semiconductor switch capable of more stable operation. The thyratron alternative switch used by the kicker power supply manufactured the radial symmetric module substrate of the 800V/2kA output which was built by LTD circuit using SiC-MOSFET. By making the power transfer structure between module substrates stacked for high voltage output into a coaxial ring type, a further reduction in inductance is realized. We report the results of evaluating a pulse output of 20kV/1kA (final specification is 40kV/2kA). Ignitron, which is used as a high-power klystron clover switch, has the potential to be discontinued in the future because it uses mercury, which has limited use worldwide. LINAC's klystron clover switches require a working output of 50kV at 120kV/40kA. We fabricated 3kV/40kA oval type module substrate using MOS gate thyristor. Report on preliminary test results.

Journal Articles

Production of the cooling towers fan bearing unit at J-PARC RCS

Fujirai, Kosuke; Suganuma, Kazuaki; Yamazaki, Yoshio

Proceedings of 16th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1162 - 1164, 2019/07

Cooling water equipment of J-PARC RCS is supplying heat source equipment of an electromagnet cooling water. The cooling water is cooled in a cooling tower established outdoors. I heard abnormal noise from the bearing unit of the cooling tower fan in April, 2015 I decided to observe the state of the bearing unit. As a result of observation, it has a wound peculiar to a bearing of the pulley side. I decided to check why a bearing of the pulley side was damaged. When a fan goes around, a bearing on the pulley side is pulled by the upper and lower movement and fan belt which occur to a crosswise direction. I guessed a peculiar bruise the pulley side was that these vibration and load were added, and to have stuck. A bearing is the structure with which grease can't be replaced by the grease shutting tightly type, and I can think a small bruise has spread by the thing detached because a thing detached by braking drove in the remaining state in the bearing. So I decided to consider the above mentioned problem, move up and down for stable driving of a gas cooler fan and produce vibration of a crosswise direction and the bearing unit able to endure the load and replenish grease periodically newly. I'll report on vibration parameter of the structure of the bearing unit produced newly and an early stage by this publication.

Journal Articles

Bunch shape monitor for the high-intensity H$$^{-}$$ beam with 3 MeV using the carbon material

Kitamura, Ryo; Futatsukawa, Kenta*; Hayashi, Naoki; Hirano, Koichiro; Kosaka, Satoshi*; Miyao, Tomoaki*; Moriya, Katsuhiro; Nemoto, Yasuo*; Oguri, Hidetomo

Proceedings of 16th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.51 - 54, 2019/07

The longitudinal measurement and tuning at the beam transport after the RFQ are important to reduce the beam loss and the emittance growth in the J-PARC linac, when the high-intensity H$$^{-}$$ beam of more than 60 mA is supplied. The new bunch shape monitor (BSM) using the carbon-nanotube (CNT) wire is necessary to measure the bunch shape of the high-intensity H$$^{-}$$ beam with 3 MeV, because the CNT wire has a high-temperature tolerance and a small energy deposit. However, when the high voltage was applied to the CNT wire to extract the secondary electron derived, the discharge prevents the power supply from applying the voltage. Therefore, the discharge should be suppressed to measure the bunch shape with stability. Considering the characteristics of the CNT as the emitter, when the length of the CNT wire was short, the high voltage of -10 kV was applied to the CNT wire. The current status and future prospects of the BSM using the CNT wire are reported in this presentation.

Journal Articles

Update of MPS modules for J-PARC Linac and RCS

Takahashi, Hiroki; Hayashi, Naoki; Nishiyama, Koichi*; Suzuki, Takahiro*; Ishiyama, Tatsuya*

Proceedings of 16th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.271 - 274, 2019/07

In the event of an abnormal situation, a machine protection system (MPS) that immediately inhibits the beam is indispensable to minimize the damage and the radioactivation by beam loss. The existing MPS was developed during the construction period of the J-PARC. Then, the system has been working stably for more than ten years. On the other hand, since there are many MPS modules that have been used from the beginning of J-PARC operation, it is important to systematically proceed with updating (replacement) of modules as a measure against aging of MPS. However, the main components of the existing MPS module have been discontinued. Therefore, it is indispensable to redesign the MPS modules in consideration of improvement such as the compatibility with existing modules and the miniaturization. In this paper, the development status of the new module and the update plan of MPS for Linac and RCS are detailed.

Journal Articles

The Fast measurement of the monitors data with the beam synchronized tag in J-PARC

Hatakeyama, Shuichiro*; Yamamoto, Kazami; Yoshimoto, Masahiro; Hayashi, Naoki

Proceedings of 16th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.789 - 793, 2019/07

The J-PARC Rapid Cycling Synchrotron (RCS) accelerates 400 MeV LINAC beams up to 3 GeV, and distributes them to the Materials Life Science Experiment Facility (MLF) and the Main Ring Synchrotron (MR) in 25 Hz cycle. To prevent radiation damages from the beam loss and also to detect failures of machines an interlock mechanism called the Machine Protection System (MPS) is introduced. If the beam is stopped by the MPS we should recover it quickly for the users of experiment facilities. The MPS related to the beam dynamics is usually diagnosed by beam loss monitors (BLM), beam position monitors (BPM) and current transformers (CT). Data of these monitors should be distinguished MLF or MR since the parameters for the magnet and the RF systems are different between MLF and MR. We confirmed validity of the method to distinguish the beam destination by using the information of the beam synchronized tag from the reflective memory (RFM) when taking the monitor data in 25 Hz.

Journal Articles

Study of heavy ion acceleration in J-PARC

Harada, Hiroyuki; Saha, P. K.; Kinsho, Michikazu

Proceedings of 16th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.179 - 182, 2019/07

Recently, humankind had big discovery about neutron star, which is great big nuclear in the space. They are discovery of neutron star with twice mass of solar in 2010 and observation of gravity wave when two neutron start incorporate in 2017. In order to understand the high dense matter like the neutron star, project of experimental researches by using accelerated heavy ion beams become heated in the world, such RHIC-BES-II program, FAIR project, NICA project, etc. The J-PARC provides MW class high intensity proton beams to many experiments and researches. We have study of the heavy ion beam in J-PARC to fully utilize high intensity ability of J-PARC. We propose the accelerator scheme of the beam in J-PARC and the intensity will reach to the world record. In our talk, we will report the current status of proton beam and the accelerator scheme for the high-intensity heavy ion beam in J-PARC.

Journal Articles

Development of ignitron alternative semiconductor switch and new kicker power supply for J-PARC accelerator

Ono, Ayato; Takayanagi, Tomohiro; Ueno, Tomoaki*; Horino, Koki*; Yamamoto, Kazami; Kinsho, Michikazu

Proceedings of 16th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.399 - 403, 2019/07

J-PARC uses an ignitron switch as the klystron power source clover device and a thyratron switch as the kicker power system. Ignitron uses mercury, which is of limited use worldwide, and is expected to be discontinued in the future. Therefore, a semiconductor switch for ignitron substitution using a MOS gate thyristor is designed. In order to be used as a crowbar device, a switch capable of resisting an operating output of 120 kV, 40 kA, 50 us is required. We have realized an oval type substrate module that achieves an operating output of 3 kV, 40 kA, 50 us per substrate. In addition, we adopted a LTD circuit using SiC-MOSFET as an alternative switch for thyratron, and produced a radially symmetric pulse power supply circuit to which this circuit was applied. This circuit board achieves a rise of 250 ns or less, and a flat top of 1.5 us or more necessary for the RCS kicker power supply system, with a pulse output of 800 V and 2 kA per circuit board. We report on the power test results at 20 kV.

Journal Articles

Status of J-PARC accelerators

Hasegawa, Kazuo; Kinsho, Michikazu; Oguri, Hidetomo; Yamamoto, Kazami; Hayashi, Naoki; Yamazaki, Yoshio; Naito, Fujio*; Yoshii, Masahito*; Toyama, Takeshi*; Yamamoto, Noboru*; et al.

Proceedings of 16th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1235 - 1239, 2019/07

After the summer shutdown in 2018, the J-PARC restarted user operation in late October. While beam power to the Materials and Life Science Experimental Facility (MLF) was 500 kW as before the summer shutdown, linac beam current was increased from 40 to 50 mA. Operation of the Main Ring (MR) was suspended due to the modification and/or maintenance of the Superkamiokande (neutrino detector) and Hadron experimental facility. The user operation was resumed in the middle of February for the Hadron experimental facility at 51 kW. But on March 18, one of the bending magnets in the beam transport line to the MR had a failure. It was temporary recovered and restored beam operation on April 5, but the failure occurred again on April 24 and the beam operation of the MR was suspended. In the fiscal year of 2018, the availabilities for the MLF, neutrino and hadron facilities are 94%, 86%, and 74%, respectively.

Journal Articles

Development of profile monitors on target for high-intensity proton accelerators

Meigo, Shinichiro; Takei, Hayanori; Matsuda, Hiroki; Yuri, Yosuke*; Yuyama, Takahiro*

Proceedings of 16th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.515 - 519, 2019/07

no abstracts in English

24 (Records 1-20 displayed on this page)