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Yamamoto, Kazami; Oguri, Hidetomo; Morishita, Takatoshi; Yamamoto, Masanobu; Kamiya, Junichiro; Shinozaki, Shinichi; Hotchi, Hideaki*; Sato, Yoichi*; Fang, Z.*
Proceedings of 16th International Particle Accelerator Conference (IPAC25) (Internet), p.1128 - 1131, 2025/11
no abstracts in English
Nakazawa, Yuga*; Cicek, E.*; Ishida, Katsuhiko*; Futatsukawa, Kenta*; Shimomura, Koichiro*; Otani, Masashi*; Kimura, Masato*; Kamioka, Shusei*; Yamazaki, Takayuki*; Mibe, Tsutomu*; et al.
Proceedings of 16th International Particle Accelerator Conference (IPAC25) (Internet), p.1163 - 1166, 2025/11
At the Japan Proton Accelerator Research Complex (J-PARC), low-emittance muon beams with a linear accelerator (linac) are proposed as a new approach to precisely measure the anomalous magnetic moment and electric dipole moment of the muon. Low-emittance muon beams can also be employed as new probes for non-destructive imaging techniques to see through structures. In the low-velocity section of the muon linac, a radio-frequency quadrupole linac (RFQ) and an interdigital H-mode drift tube linac (IH-DTL) are used to accelerate muons to 
= v/c = 0.08 and 0.28, respectively, at an operating frequency of 324 MHz. To reduce construction costs, the IH-DTL employs the alternating phase focusing (APF) method, which uses the transverse focusing force derived from the RF electric field. Because the APF method limits the transverse and longitudinal acceptances simultaneously, careful beam diagnostics and commissioning are essential to suppress the emittance growth derived from beam mismatches. As a result of the beam simulation, by conducting appropriate beam matching, the normalized rms emittance of 0.3 
-mm-mrad and the transmission to the downstream detector of 97% was obtained. In this paper, the results of the tracking simulation and the development status of the diagnostic and transport beamlines in the low-velocity section are described.
Kitamura, Ryo; Morishita, Takatoshi; Okabe, Kota; Miyao, Tomoaki*; Nakazawa, Yuga*; Shibata, Takanori*
Proceedings of 16th International Particle Accelerator Conference (IPAC25) (Internet), p.2811 - 2813, 2025/11
ion beam at J-PARC frontendShibata, Takanori*; Nammo, Kesao*; Shinto, Katsuhiro; Okoshi, Kiyonori; Kawai, Isao*; Kitamura, Ryo; Morishita, Takatoshi; Kondo, Yasuhiro; Sato, Yoichi*
Proceedings of 16th International Particle Accelerator Conference (IPAC25) (Internet), p.514 - 516, 2025/11
no abstracts in English
Liu, Y.*; Otani, Masashi*; Miyao, Tomoaki*; Nakazawa, Yuga*; Shibata, Takanori*; Nammo, Kesao*; Fang, Z.*; Futatsukawa, Kenta*; Fukui, Yuji*; Mizobata, Satoshi*; et al.
Proceedings of 16th International Particle Accelerator Conference (IPAC25) (Internet), p.855 - 857, 2025/11
Kondo, Ayaka*; Iijima, Toru*; Sumi, Kazumichi*; Takeuchi, Yusuke*; Cicek, E.*; Ego, Hiroyasu*; Otani, Masashi*; Nakazawa, Yuga*; Futatsukawa, Kenta*; Mibe, Tsutomu*; et al.
Journal of Physics; Conference Series, 3094(1), p.012025_1 - 012025_6, 2025/09
A muon linear accelerator is under development at J-PARC for precise measurement of the muon anomalous magnetic moment (g-2) and electric dipole moment (EDM). Adisk-and-washer (DAW) structure is employed to accelerate muons from 30% of the speed of light (kinetic energy 4 MeV) to 70% (40 MeV) at 1296 MHz. The muon DAWconsists of tanks accelerating the muons and bridge couplers that couple the tanks and focus the beam using an internal quadrupole doublet. A bridge-coupler prototype is currently being fabricated and will be tested. This paper presents the design and performance evaluation of the bridge coupler prototype.
Morishita, Takatoshi
Kasokuki, 21(4), p.288 - 296, 2025/01
no abstracts in English
Yamamoto, Kazami; Moriya, Katsuhiro; Okita, Hidefumi; Yamada, Ippei; Chimura, Motoki; Saha, P. K.; Shobuda, Yoshihiro; Tamura, Fumihiko; Yamamoto, Masanobu; Morishita, Takatoshi; et al.
Journal of Neutron Research, 26(2-3), p.59 - 67, 2024/01
The linac and 3 GeV rapid cycling synchrotron at the Japan Proton Accelerator Research Complex was designed to provide 1-MW proton beams to the following facilities. Thanks to the improvement works of the accelerator system, we successfully accelerate 1-MW beam with quite small beam loss. Currently, the beam power of RCS is limited by the lack of anode current in the RF cavity system rather than the beam loss. Recently we developed a new acceleration cavity that can accelerate a beam with less anode current. This new cavity enables us not only to reduce requirement of the anode power supply but also to accelerate more than 1-MW beam. We have started to consider the way to achieve beyond 1-MW beam acceleration. So far, it is expected that up to 1.5-MW beam can be accelerated after replacement of the RF cavity. We have also been continuing study to achieve up to 2 MW beam in J-PARC RCS.
Kitamura, Ryo; Hayashi, Naoki; Hirano, Koichiro; Kosaka, Satoshi*; Miyao, Tomoaki*; Morishita, Takatoshi; Nemoto, Yasuo*
Journal of Physics; Conference Series, 2687(7), p.072006_1 - 072006_6, 2024/01
Times Cited Count：0 Percentile：0.00(Physics, Atomic, Molecular & Chemical)The mitigation of heat loading is one of the important issues for beam instrumentation to measure the high-power proton beam. Recently, the highly-oriented pyrolytic graphite (HOPG) material was used for the target probe of the bunch-shape monitor at the front-end in the Japan Proton Accelerator Research Complex (J-PARC). Since the thermal conductivity of the HOPG is high, it is suitable to measure the beam profile under the condition of high heat loading. As an application of the HOPG, for example, the thin HOPG may be used as a substitutive material of the target wire for the transverse profile monitor such as the wire scanner monitor. The possibility of the HOPG target for the beam profile monitor is discussed from some results of the test experiment using the 3-MeV negative hydrogen ion beam at the test stand.
Yamamoto, Kazami; Moriya, Katsuhiro; Okita, Hidefumi; Yamada, Ippei; Chimura, Motoki; Saha, P. K.; Shobuda, Yoshihiro; Tamura, Fumihiko; Yamamoto, Masanobu; Morishita, Takatoshi; et al.
Proceedings of 68th ICFA Advanced Beam Dynamics Workshop on High Intensity and High Brightness Hadron Beams (HB2023) (Internet), p.270 - 273, 2023/10
The 3-GeV rapid-cycling synchrotron at the Japan Pro-ton Accelerator Research Complex was designed to provide 1-MW proton beams to the following facilities. Thanks to the improvement works of the accelerator system, we successfully accelerate 1-MW beam with quite small beam loss. Currently, the beam power of RCS is limited by the lack of anode current in the RF cavity system rather than the beam loss. Recently we developed a new acceleration cavity that can accelerate a beam with less anode current. This new cavity enables us not only to reduce requirement of the anode power supply but also to accelerate more than 1-MW beam. We have started to consider the way to achieve beyond 1-MW beam acceleration. So far, it is expected that up to 1.5-MW beam can be accelerated after replacement of the RF cavity. We have also continued study to achieve more than 2 MW beam in J-PARC RCS.
particles generated by residual gas stripping in the Japan Proton Accelerator Research Complex linacTamura, Jun; Futatsukawa, Kenta*; Kondo, Yasuhiro; Liu, Y.*; Miyao, Tomoaki*; Morishita, Takatoshi; Nemoto, Yasuo*; Okabe, Kota; Yoshimoto, Masahiro
Nuclear Instruments and Methods in Physics Research A, 1049, p.168033_1 - 168033_7, 2023/04
Times Cited Count：2 Percentile：31.51(Instruments & Instrumentation)The Japan Proton Accelerator Research Complex (J-PARC) linac is a high-intensity accelerator in which beam loss is a critical issue. In the J-PARC linac, H
beams are accelerated to 191~MeV by a separated drift tube linac (SDTL) and subsequently to 400~MeV by an annular-ring coupled structure (ACS). Because there are more beam loss mechanisms in H linacs than in proton linacs, it is imperative to investigate the beam loss circumstances for beam loss mitigation. Electron-stripping phenomena, which generate uncontrollable H particles, are characteristic beam loss factors of H linacs. To clarify the beam loss causes in the J-PARC linac, a new diagnostic line was installed in the beam transport between the SDTL and ACS. In this diagnostic line, H particles were separated from the H beam, and the intensity profiles of the H particles were successfully measured by horizontally scanning a graphite plate in the range where H particles were distributed. By examining the intensity variation of the H particles with different residual pressure levels, we proved that half of the H particles in the SDTL section are generated by the residual gas stripping in the nominal beam operation of the J-PARC linac.
Kitamura, Ryo; Futatsukawa, Kenta*; Hayashi, Naoki; Hirano, Koichiro; Kondo, Yasuhiro; Kosaka, Satoshi*; Miyao, Tomoaki*; Morishita, Takatoshi; Nemoto, Yasuo*; Oguri, Hidetomo
Physical Review Accelerators and Beams (Internet), 26(3), p.032802_1 - 032802_12, 2023/03
Times Cited Count：6 Percentile：67.70(Physics, Nuclear)A bunch-shape monitor (BSM) is a useful device for performing longitudinal beam tuning using the pointwise longitudinal phase distribution measured at selected points in the beam transportation. To measure the longitudinal phase distribution of a low-energy negative hydrogen (H) ion beam, highly oriented pyrolytic graphite (HOPG) was adopted for the secondary-electron-emission target to mitigate the thermal damage due to the high-intensity beam loading. The HOPG target enabled the measurement of the longitudinal phase distribution at the center of a 3-MeV H ion beam with a high peak current of about 50 mA. The longitudinal bunch width was measured using HOPG-BSM at the test stand, which was consistent with the beam simulation. The correlation measurement between the beam transverse and longitudinal planes was demonstrated using HOPG-BSM. The longitudinal Twiss and emittance measurement with the longitudinal Q-scan method was conducted using HOPG-BSM.
Cicek, E.*; Futatsukawa, Kenta*; Fang, Z.*; Fukui, Yuji*; Mizobata, Satoshi*; Otani, Masashi*; Kondo, Yasuhiro; Morishita, Takatoshi; Nakazawa, Yuga*; Sato, Yoshikatsu*
Nuclear Instruments and Methods in Physics Research A, 1046, p.167700_1 - 167700_8, 2023/01
Times Cited Count：0 Percentile：0.00(Instruments & Instrumentation)The digital feedback (DFB) setup employed in a low-level radio frequency (LLRF) control system is crucial to ensure RF field stability in accelerating cavities. To this end, a novel in-house and multi-purpose prototype DFB setup was developed for multiple applications at the Japan Proton Accelerator Research Complex (J-PARC). Being efficient, low-cost, and compact is key to achieving a cost-effective system that fulfills the performance specifications. A field-programmable gate array (FPGA)-based design with a digital signal processing (DSP) function is used. This arrangement compensates for RF phase fluctuations and amplitude modulations by employing a proportional and integral (PI) feedback controller. The system was utilized to conduct high-power tests on the interdigital H-mode drift-tube linac (IH-DTL) cavity of a muonlinac for short RF pulses. The setup was also tested on a buncher cavity (Buncher-2) in the J-PARC linac, achieving efficient performance for longer RF pulses. The stability of the RF accelerating field in the IH-DTL was achieved at 
0.25% peak-to-peak (pp) in amplitude and 0.36 degree pp in phase. For the Buncher-2, the amplitude stability of 0.18% pp and phase stability of 0.13 degree pp were obtained. This study discusses the design aspects of a cost-effective DFB system and reports high-power measurements.
Kitamura, Ryo; Hayashi, Naoki; Hirano, Koichiro; Miyao, Tomoaki*; Miura, Akihiko; Morishita, Takatoshi
Proceedings of 19th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.212 - 214, 2023/01
In the J-PARC linac, the bunch-shape monitor (BSM) is developed to precisely and rapidly measure the longitudinal beam profile at the front-end, towards the improvement of the beam matching. The graphite target having the good strength to the high-power beam, has been introduced in order to resist the heat loading of the high-intensity beam. The resolution and other uncertainties were evaluated for the BSM. The longitudinal Twiss parameters and emittance were measured using the BSM and the IMPACT, which was the 3D particle-in-cell simulation code. The precision of the longitudinal emittance measurement was improved, by implementing uncertainties related to the BSM into the calculation. In this presentation, we will report a series of the measurement result, the method of the beam diagnostics with the BSM at the front-end, and the comparison between the measurement and the beam simulation.
Oda, Kodai; Takayanagi, Tomohiro; Ono, Ayato; Horino, Koki*; Ueno, Tomoaki*; Sugita, Moe; Morishita, Takatoshi; Iinuma, Hiromi*; Tokuchi, Akira*; Kamezaki, Hiroaki*; et al.
Proceedings of 19th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.610 - 614, 2023/01
Kicker system is being used to kick the accelerated 3 GeV beam into the transport lines in RCS of J-PARC. The current kicker power supply applies thyratrons to discharge switches. We are developing a new kicker power supply using next-generation power semiconductors. The timing of the semiconductor switch operation is determined by the input of an external trigger signal. Large timing jitter causes unstable output pulses and beam loss due to beam orbit deviate from reference orbit. Therefore, a low jitter circuit that achieves high repeatability of 2 ns or less will be developed for the new kicker power supply. A prototype trigger generator has been fabricated, and jitter has been evaluated. The results of the evaluation test and the circuit configuration plan for reducing jitter will be reported.
beamKitamura, Ryo; Hayashi, Naoki; Hirano, Koichiro; Kosaka, Satoshi*; Miyao, Tomoaki*; Nemoto, Yasuo*; Morishita, Takatoshi
Proceedings of 19th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.330 - 332, 2023/01
In the J-PARC linac, a new bunch-shape monitor (BSM) is developed to stably measure the high-intensity and low-energy H beam by improving the strength of the target probe for the heat loading. The new target probe is made of the graphite. The first measurement of the longitudinal beam profile has been realized with the BSM at the core region of the high-intensity beam. Since the beam profile can be measured with the new BSM at any transverse position thanks to the new target probe, we propose the advanced application of the beam diagnostics with the BSM. In this presentation, some new approaches of the beam diagnostics with the BSM; the transverse profile measurement using the secondary electrons and the beam current evaluation from the transverse profile measurement, are discussed beyond the original usage of the BSM.
-2 and electric dipole moment experimentNakazawa, Yuga*; Cicek, E.*; Futatsukawa, Kenta*; Fuwa, Yasuhiro; Hayashizaki, Noriyosu*; Iijima, Toru*; Iinuma, Hiromi*; Iwata, Yoshiyuki*; Kondo, Yasuhiro; Mibe, Tsutomu*; et al.
Physical Review Accelerators and Beams (Internet), 25(11), p.110101_1 - 110101_9, 2022/11
Times Cited Count：4 Percentile：43.95(Physics, Nuclear)We conducted a high-power test of a prototype cavity of a 324-MHz interdigital H-mode drift tube linac (IH-DTL) for the precise measurement of the muon anomalous magnetic moment (-2) and electric dipole moment (EDM). This prototype cavity (short IH) was developed to verify the fabrication methodology for the IH-DTL cavity with a monolithic drift tube structure. The electromagnetic field distribution was measured and compared with the finite element method simulation results, and the fabrication accuracy of the monolithic drift tube was confirmed to satisfy the requirements. After 40 h of conditioning, the short IH was stably operated with an rf power of 88 kW, which corresponds to a 10% higher accelerating field than the design field (E0) of 3.0 MV/m. In addition, the thermal characteristics and frequency response were measured, verifying that the experimental data were consistent with the three-dimensional model. In this paper, the design, fabrication, and low-power and high-power tests of this IH-DTL for muon acceleration are described.
Nakazawa, Yuga*; Iinuma, Hiromi*; Iwata, Yoshiyuki*; Cicek, E.*; Ego, Hiroyasu*; Futatsukawa, Kenta*; Kawamura, Naritoshi*; Mibe, Tsutomu*; Mizobata, Satoshi*; Otani, Masashi*; et al.
Proceedings of 31st International Linear Accelerator Conference (LINAC 2022) (Internet), p.275 - 278, 2022/09
We conducted a high-power test of a prototype cavity of a 324-MHz inter-digital H-mode drift tube linac (IH-DTL) for the muon g-2/EDM experiment at J-PARC. This prototype cavity (short-IH) was developed to verify the fabrication methodology for the full-length IH cavity with a monolithic DT structure. After 40 h of conditioning, the short-IH has been stably operated with an RF power of 88 kW, which corresponds to 10% higher accelerating field than the design field (E0) of 3.0 MV/m. In addition, the thermal characteristics and frequency response were measured, verifying that the experimental data was consistent with the three-dimensional model. In this paper, the high-power tests of this IH-DTL for muon acceleration are described.
Takeuchi, Yusuke*; Tojo, Junji*; Yamanaka, T.*; Nakazawa, Yuga*; Iinuma, Hiromi*; Kondo, Yasuhiro; Kitamura, Ryo; Morishita, Takatoshi; Cicek, E.*; Ego, Hiroyasu*; et al.
Proceedings of 31st International Linear Accelerator Conference (LINAC 2022) (Internet), p.562 - 564, 2022/09
A muon linac is under development for future muon g-2/EDM experiments at J-PARC. The linac provides a 212 MeV muon beam to an MRI-type compact storage ring. After the initial acceleration using the electrostatic field created by mesh and cylindrical electrodes, the muons are accelerated using four types of radio-frequency accelerators. To validate the linac design as a whole, end-to-end simulations were performed using General Particle Tracer. In addition, error studies were performed to investigate the effects on beam and spin dynamics of various errors in the accelerator components and input beam distribution. This paper describes the results of the end-to-end simulations and error studies.
Tamura, Jun; Kondo, Yasuhiro; Morishita, Takatoshi; Naito, Fujio*; Otani, Masashi*
Proceedings of 31st International Linear Accelerator Conference (LINAC 2022) (Internet), p.177 - 179, 2022/09
Various types of cavity structures are typically used in hadron linacs, depending on the energy range of the beam particle. This is especially the case in a normal-conducting linac, because the cavity's acceleration efficiency varies with the velocity of the synchronous particle. For low-energy proton acceleration, while Alvarez drift-tube linacs (DTLs) are the most prevalent, TE-mode accelerating structures, which could also be called H-mode structures, are also widely used immediately after an initial radiofrequency quadrupole linac (RFQ). At present, the representative structures of TE modes are interdigital H-mode (IH) DTL and crossbar H-mode (CH) DTL, which are based on the TE11-mode pillbox cavity and TE21-mode pillbox cavity, respectively. In this presentation, acceleration efficiency of TE-mode structures including higher-order TE-modes such as TE31 and TE41 was comparatively reviewed with Alvarez DTL. This study shows that IH-DTL and CH-DTL have a larger shunt impedance than Alvarez DTL for proton acceleration below 10 MeV, and furthermore for the TEm1-mode structures, the rotational symmetry of the electric field improves with increasing angular index m.
