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Shibata, Takanori*; Sugimura, Takashi*; Ikegami, Kiyoshi*; Takagi, Akira*; Sato, Masaharu*; Naito, Fujio*; Okoshi, Kiyonori; Hasegawa, Kazuo
JPS Conference Proceedings (Internet), 33, p.011009_1 - 011009_6, 2021/03
Upgrade of beam current in the Linac of Ibaraki Boron Neutron Capture Therapy (iBNCT) is one of the most important requirements to realize clinical trial. By 2018, the measurement of the produced neutrons characteristics and the neutron irradiation experiment for living cells have been done by producing 8-MeV proton beam current at the beryllium target with average current up to 2 mA. In order to satisfy the original clinical trial conditions, 5 mA average beam current is required at the target. For this goal, peak beam current extracted from the ion source should be increased to 60 mA from the present 30 mA with duty factor up to more than 10% (pulse width up to 1 ms and repetition rate up to more than 100 Hz). Stability of the peak current in the macro pulse is also important for the clinical application.
Yako, Tomoki*; Iwashita, Yoshihisa*; Abe, Masashi*; Kurihara, Toshikazu*; Fukuda, Masafumi*; Sato, Masaharu*; Sugimura, Takashi*; Fuwa, Yasuhiro; Takamiya, Koichi*; Iinuma, Yuto*
Proceedings of 16th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1003 - 1005, 2019/10
Permanent magnets are used as materials for beam optics elements, but it is known that radiation demagnetization occurs in neodymium magnets and samarium cobalt magnets. However, there is not enough information on the radiation demagnetization of ferrite magnets which is weak in strength but inexpensive. In order to verify the suitability of the ferrite magnet as a beam optics element, radiation demagnetization experiments by neutron irradiation of the ferrite magnet were carried out at the Kyoto University Research Reactor (KUR). In the experiment, neutron fluence up to 
cm
was irradiated, and no significant demagnetization was detected on the fluence.
filament arc-driven multi-cusp ion source for iBNCTShibata, Takanori*; Takagi, Akira*; Ikegami, Kiyoshi*; Sugimura, Takashi*; Nammo, Kesao*; Naito, Fujio*; Kobayashi, Hitoshi*; Kurihara, Toshikazu*; Honda, Yosuke*; Sato, Masaharu*; et al.
Proceedings of 15th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.385 - 387, 2018/10
Hirano, Koichiro; Sugimura, Takashi*; Kurihara, Toshikazu*
Proceedings of 15th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.324 - 328, 2018/08
We could use a 3 MeV beam scraper without a problem for five months when the scraper received to 1.3 times as high as a normal average beam current of the scraper in 1MW beam operation. The peak temperature on the scraper surface was 1800
C. Irradiation damage caused by the 3 MeV beam with particle number of 3E22 was 700 
m depth. We study scraper materials which can withstand the current density higher than carbon composite used in the scraper because almost all beams can be irradiated to the scraper in 1 MW beam operation. Beam irradiation tests have been performed about graphene and tungsten as scraper materials with high heat conductivity. This paper describes beam irradiation test of the 3 MeV beam scraper and scraper materials.
Hirano, Koichiro; Ishiyama, Tatsuya; Kurihara, Toshikazu*; Sugimura, Takashi*; Maruta, Tomofumi*
Proceedings of 14th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.847 - 852, 2017/12
Beam scrapers made of carbon composite have been used in the MEBT1 between a 324 MHz RFQ and a 50-MeV DTL of the J-PARC Linac. We have conducted the scraper irradiation test with the 3 MeV linac. The test piece of the scraper was irradiated by the H
beam up to particle number of 1.2E20. We measured the surface temperature of more than 3000C using a high-speed radiation thermometer and observed the irradiation damage on the scraper by using the laser microscope. When the surface temperature exceeded 2900C, the ionic current of carbon and the irradiation damage on the surface of the test piece rapidly increased. This paper describes beam irradiation test results of the scraper.
Ito, Takashi; Morishita, Takatoshi; Tamura, Jun; Nammo, Kesao*; Sugimura, Takashi*
Proceedings of 8th International Particle Accelerator Conference (IPAC '17) (Internet), p.4184 - 4186, 2017/06
We have suffered from multipactor problem of some SDTLs after the Great East Japan Earthquake. As a designed operating rf power of the SDTL is in the multipactor region, we had to operate at higher power of the designed one. From the result of the simulation and the observation of the SDTL cavity, it became clear that the multipactor occurred on the inner surface of the cavity. We think that one of the cause of the multifactor is the contamination on the inner surface of the cavity, we performed the cleaning of the inner surface of the cavity by using acetone. The cleaning was very effective and the multipactor region was reduced or disappeared. The multipactor problem has not occurred since then.
Kondo, Yasuhiro; Asano, Hiroyuki*; Chishiro, Etsuji; Hirano, Koichiro; Ishiyama, Tatsuya; Ito, Takashi; Kawane, Yusuke; Kikuzawa, Nobuhiro; Meigo, Shinichiro; Miura, Akihiko; et al.
Proceedings of 28th International Linear Accelerator Conference (LINAC 2016) (Internet), p.298 - 300, 2017/05
We have constructed a linac for development of various accelerator components at J-PARC. The ion source is same as the J-PARC linac's, and the RFQ is a used one in the J-PARC linac. The beam energy is 3 MeV and nominal beam current is 30 mA. The accelerator has been already commissioned, and the first development program, laser-charge-exchange experiment for the transmutation experimental facility, has been started. In this paper, present status of this 3-MeV linac is presented.
Hirano, Koichiro; Asano, Hiroyuki; Ishiyama, Tatsuya; Ito, Takashi; Okoshi, Kiyonori; Oguri, Hidetomo; Kondo, Yasuhiro; Kawane, Yusuke; Kikuzawa, Nobuhiro; Sato, Yoshikatsu; et al.
Proceedings of 13th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.310 - 313, 2016/11
We have used a beam scraper with the incident angle of 65deg to reduce the beam power deposition density in the MEBT between a 324 MHz RFQ and a 50-MeV DTL of the J-PARC linac. The 65 scraper was irradiated by the H beam up to particle number of 1.47E22. We observed a lot of surface projections with several hundred micrometers high in the beam irradiation damage on the scraper by using the laser microscope. In order to study the limits of scrapers, we constructed a new 3 MeV linac at J-PARC. We will conduct the scraper irradiation test at the end of this year.
Sugimura, Takashi*; Maruta, Tomofumi*; Hirano, Koichiro
Proceedings of 13th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.307 - 309, 2016/11
There is an upgrade plan of J-PARC (Japan Proton Accelerator Research Complex) Linac from currently operated beam parameters such as, beam current of 40 mA, beam pulse width of 0.5msec and repetition of 25 Hz, to 50 mA, 0.5msec and 50 Hz, respectively. To reduce beam loss during a beam acceleration is a must task to accelerate a high power beam. At J-PARC Linac, a beam from an ion source followed by RFQ (Radio Frequency Quadrupole) injected into a series of DTLs (Drift Tube Linac) through a MEBT1 (Medium Energy Beam Transport 1), where a beam matching and a beam pulse forming are carried out at the beam energy of 3 MeV. There are some locally activated spots in DTL area at the current beam power level so that some kind of mitigation measure is required. Beam simulation results show that the beam loss at the DTL area can be reduced if there is a pair of vertical beam collimators. This paper reports a design and fabrication status of new vertical collimators.
Kurihara, Toshikazu*; Kobayashi, Hitoshi*; Sugimura, Takashi*; Hirano, Koichiro
Proceedings of 13th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.814 - 816, 2016/11
A problem of irradiation damage is the one observed in each part of a component of particle accelerators; accelerating tubs, scrapers, monitors and neutron targets. In-situ observation by an actual proton accelerator is made our last target. We observed the radiation damage of the various materials used by particle accelerators. From the distant place the target which is in the high radiation area, we propose the method to get information from the catoptric light from the target using a laser as a light source. A principle of this observation method as well as generating process of blisterings and limitation of this method will be reported.
Hirano, Koichiro; Kondo, Yasuhiro; Kawane, Yusuke; Shinozaki, Shinichi; Miura, Akihiko; Morishita, Takatoshi; Sawabe, Yuki; Sugimura, Takashi*; Naito, Fujio*; Fang, Z.*; et al.
Proceedings of 12th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.944 - 947, 2015/09
Two RF-deflecting cavities as a chopper and a beam scraper have been used in the MEBT1 between a 324 MHz RFQ and a 50-MeV DTL of the J-PARC Linac. We replaced with a newly fabricated RF chopper to decrease beam loss for the operation with 50 mA. We installed two new scrapers to absorb the higher power of the deflected beam by the RF chopper. This paper describes the RF chopper system and beam irradiation test results of the scraper.
Sugimura, Takashi*; Hirano, Koichiro
Proceedings of 12th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.954 - 957, 2015/09
The beam power of 1MW is a design specification of J-PARC. Therefore the beam current upgrade to 50 mA in the injector linac is indispensable. The scrapers installed in the linac have been took waste beam out of RFQ since last summer. They consist of Carbon composite surface plates and Copper block with cooling-water channel. The deterioration of thermal conducting has been observed during daily operation. Thus, a newly designed scraper with a large entry angle of 67 is introduced as countermeasures. This paper reports the results of numeric simulations of the new scrapers and their installation schedule.
Nemoto, Yasuo; Tamura, Jun; Ito, Takashi; Morishita, Takatoshi; Hirano, Koichiro; Kondo, Yasuhiro; Oguri, Hidetomo; Sugimura, Takashi*; Nammo, Kesao*; Ao, Hiroyuki*
Proceedings of 12th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1101 - 1104, 2015/09
In J-PARC linac, ACS (Annular-ring Coupled Structure) has been operating for one and a half years. Through the long term operation, the ACS cavities have been well conditioned. Therefore, the vacuum pressure of the ACS was reduced to 1
10
Pa, which is much lower than the required value, and RF trip rate was steadily decreased. At present, the ACS continues to be stably operating without sacrificing the operating time of the J-PARC accelerator complex. The vacuum leaks caused by the generated crack in the aluminum chain clamps in the ACS beam line have happened five times in the past. To prevent the same situation from occurring, we replaced all the aluminum clamps to the stainless steel clamps. The residual radiation between each ACS cavity is considerably high. It is considered that the CT monitors, which have smaller aperture than that of other instruments in the beam line, contributes to the residual radiation. We are trying to reduce the residual radiation by enlarging the monitor's aperture and by replacing the unused monitors to the titanium ducts in this summer shutdown period.
Kondo, Yasuhiro; Morishita, Takatoshi; Yamazaki, Saishun; Hori, Toshihiko; Sawabe, Yuki; Chishiro, Etsuji; Fukuda, Shimpei; Hasegawa, Kazuo; Hirano, Koichiro; Kikuzawa, Nobuhiro; et al.
Physical Review Special Topics; Accelerators and Beams, 17(12), p.120101_1 - 120101_8, 2014/12
Times Cited Count：6 Percentile：42.9(Physics, Nuclear)We performed a beam test of a new radio frequency quadrupole linac (RFQ III) for the beam current upgrade of the Japan Proton Accelerator Research Complex. First, the conditioning of RFQ III was conducted, and after 20 h of conditioning, RFQ III became very stable with a nominal peak power and duty factor of 400 kW and 1.5%, respectively. An off-line beam test was subsequently conducted before installation in the accelerator tunnel. The transmission, transverse emittance, and energy spread of the 50-mA negative hydrogen beam from RFQ III were measured and compared with simulation results. The experiment and simulation results showed good agreement; therefore, we conclude that the performance of RFQ III conforms to its design.
Oguri, Hidetomo; Hasegawa, Kazuo; Ito, Takashi; Chishiro, Etsuji; Hirano, Koichiro; Morishita, Takatoshi; Shinozaki, Shinichi; Ao, Hiroyuki; Okoshi, Kiyonori; Kondo, Yasuhiro; et al.
Proceedings of 11th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.389 - 393, 2014/10
no abstracts in English
Kawane, Yusuke*; Miura, Akihiko; Miyao, Tomoaki*; Hirano, Koichiro; Sugimura, Takashi*; Kato, Yuko; Sawabe, Yuki; Fukuda, Shimpei; Ouchi, Nobuo
Proceedings of 11th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1288 - 1291, 2014/10
In the J-PARC Linac, because an upgrading of a beam current up to 50mA using an RF-driven ion source and a new RFQ Linac cavity is in progress, we have developed a new frontend equipments. In order to protect the scraper against 50 mA, we need to observe the temperature and to avoid the excess heat loading of the scraper surface and to count the irradiated beam particles. We also monitor the beam transmission between the upstream and downstream of the chopper cavity to check the chopping errors using the beam current monitors. We fabricated the interlock system for the temperature, irradiated particle numbers and beam transmission. And we tested them in the test stand with actual beam. This paper describes the interlock system and their test results.
Hirano, Koichiro; Ito, Takashi; Kondo, Yasuhiro; Shinozaki, Shinichi; Chishiro, Etsuji; Miura, Akihiko; Morishita, Takatoshi; Ikegami, Masanori*; Kubota, Chikashi*; Sugimura, Takashi*; et al.
Proceedings of 10th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.858 - 861, 2014/06
Two RF-deflecting cavities as a chopper and a beam scraper have been used in the MEBT between a 324 MHz RFQ and a 50-MeV DTL of the J-PARC Linac. We plan to increase a peak beam current up to 50 mA by replacing an ion source and a RFQ after the summer shutdown in 2014. Beam loss occurs in the RF chopper for the 50 mA operation. Moreover, the beam scraper cannot fully stand the beam load with 50 mA, 0.5 ms, 3 MeV, and 25 Hz. We have studied the new RF chopper cavity by using HFSS code and the tandem scraper system with two scrapers.
Miyao, Tomoaki*; Miura, Akihiko; Kondo, Yasuhiro; Morishita, Takatoshi; Sugimura, Takashi*; Ouchi, Nobuo; Oguri, Hidetomo; Maruta, Tomofumi*; Naito, Fujio
Proceedings of 10th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1049 - 1052, 2014/06
In J-PARC linac, a project for energy and intensity upgrade has been progressed using 50 mA RFQ(Radio-Frequency-Quadrupole) linac cavity. Because the RFQ had already fabricated, test stand for its performance test was newly produced. In the test stand, we designed and fabricated the monitoring system including beam current monitors for the beam transmission measurement and the beam phase monitors for the energy measurement. We will refer the detail of the monitoring system and the data obtained during the performance test. New testing devices are also mentioned.
Sugimura, Takashi*; Hirano, Koichiro; Nammo, Kesao*; Kurihara, Toshikazu*
Proceedings of 10th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.862 - 866, 2014/06
By introducing a new ion source and a new RFQ, beam current will increase from 20 mA to 50 mA. According to an increase of the beam current, wasted beam that should not be accelerated in the following accelerator sections also increase. To stop wasted beam, there is a beam scraper in the MEBT region just after the RFQ at the beam energy of 3 MeV. An existing beam scraper is made of carbon composite material and it has a dent caused by merely small beam current of 20 mA in daily operation. A new scraper that endures upgraded beam current of 50 mA is the essential item for the beam power upgrade of J-PARC. Thermal simulations on several materials have been performed with the ANSYS code assuming the upgraded beam power. They revealed that maximum temperatures in a beam cycle are much higher than their melting points in some materials and consequently that lessening of heat load for a scraper by beam operation is an essential factor.
Ito, Takashi; Hirano, Koichiro; Sugimura, Takashi*; Nammo, Kesao*
Proceedings of 10th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.977 - 981, 2014/06
The Japan Proton Accelerator Research Complex (J-PARC) facilities were extensively damaged by the Great East Japan Earthquake on March 2011. We restarted the beam operation in December 2011 after the recovery works. However, a multipactor problem of SDTL5B cavity was occurred after the beam restoration. To solve this problem, we performed the analysis of the impurities on the inner surface of the cavity, adopted the countermeasure that is the improvement of the vacuum condition of the cavity and performed the conditioning of the cavity carefully in the summer maintenance period of 2012. By adopting the countermeasure and conditioning, the multipactor problem improved just after the beam restoration and the operation power had been decreased. We present the result of the countermeasures and the present operation status of the SDTL5 in this report.
