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Kondo, Yasuhiro; Kitamura, Ryo; Fuwa, Yasuhiro; Morishita, Takatoshi; Moriya, Katsuhiro; Takayanagi, Tomohiro; Otani, Masashi*; Cicek, E.*; Ego, Hiroyasu*; Fukao, Yoshinori*; et al.
Proceedings of 31st International Linear Accelerator Conference (LINAC 2022) (Internet), p.636 - 641, 2022/09
The muon linac project for the precise measurement of the muon anomalous magnetic and electric dipole moments, which is currently one of the hottest issues of the elementary particle physics, is in progress at J-PARC. The muons from the J-PARC muon facility are once cooled to room temperature, then accelerated up to 212 MeV with a normalized emittance of 1.5 
mm mrad and a momentum spread of 0.1%. Four types of accelerating structures are adopted to obtain the efficient acceleration with a wide beta range from 0.01 to 0.94. The project is moving into the construction phase. We already demonstrated the re-acceleration scheme of the decelerated muons using a 324-MHz RFQ in 2017. The high-power test of the 324-MHz Interdigital H-mode (IH) DTL using a prototype cavity was performed in 2021. The fabrication of the first module of 14 modules of the 1296-MHz Disk and Washer (DAW) CCL will be done to confirm the production process. Moreover, the final design of the travelling wave accelerating structure for the high beta region is also proceeding. In this paper, the recent progress toward the realization of the world first muon linac will be presented.
Sumi, Kazumichi*; Iijima, Toru*; Inami, Kenji*; Sue, Yuki*; Yotsuzuka, Mai*; Ego, Hiroyasu*; Otani, Masashi*; Saito, Naohito*; Mibe, Tsutomu*; Yoshida, Mitsuhiro*; et al.
Journal of Physics; Conference Series, p.012038_1 - 012038_6, 2022/07
The disk-loaded structures (DLS) in the muon LINAC are under development for the J-PARC muon g-2/EDM experiment. Four DLSs with an accelerating gradient of 20 MV/m take charge of muon acceleration from 40 MeV to 212 MeV, which corresponds to 70% to 94% of the speed of light. The quasi-constant gradient type TM01-2/3 mode DLSs with gradually varying disk spacing was designed and it was confirmed that the cumulative phase slip due to the mismatch between muon and phase velocity can be suppressed to less than 2 degrees at the frequency of 2592 MHz. In addition, the optimum synchronous phase and the lattice were investigated to satisfy the requirements of the total emittance less than 1.5 mm mrad and the momentum spread less than 0.1% in RMS.
Sue, Yuki*; Yotsuzuka, Mai*; Futatsukawa, Kenta*; Hasegawa, Kazuo; Iijima, Toru*; Iinuma, Hiromi*; Inami, Kenji*; Ishida, Katsuhiko*; Kawamura, Naritoshi*; Kitamura, Ryo; et al.
Physical Review Accelerators and Beams (Internet), 23(2), p.022804_1 - 022804_7, 2020/02
Times Cited Count：2 Percentile：20.59(Physics, Nuclear)A destructive monitor to measure the longitudinal bunch width of a low-energy and low-intensity muon beam was developed. This bunch-width monitor (BWM) employed microchannel plates to detect a single muon with high time resolution. In addition, constant-fraction discriminators were adopted to suppress the time-walk effect. The time resolution was measured to be 65 ps in rms using a picosecond-pulsed laser. This resolution satisfied the requirements of the muon linac of the J-PARC E34 experiment. We measured the bunch width of negative-muonium ions accelerated with a radio-frequency quadrupole using the BWM. The bunch width was successfully measured to be 
54 
11 ns, which is consistent with the simulation.
Otani, Masashi*; Fukao, Yoshinori*; Futatsukawa, Kenta*; Kawamura, Naritoshi*; Matoba, Shiro*; Mibe, Tsutomu*; Miyake, Yasuhiro*; Shimomura, Koichiro*; Yamazaki, Takayuki*; Hasegawa, Kazuo; et al.
Journal of Physics; Conference Series, 1350, p.012067_1 - 012067_6, 2019/12
Times Cited Count：3 Percentile：78.48(Physics, Particles & Fields)Negative muonium atom (
e
e, Mu) has unique features stimulating potential interesting for several scientific fields. Since its discovery in late 1980's in vacuum, it has been discussed that the production efficiency would be improved using a low-work function material. C12A7 was a well-known insulator as a constituent of alumina cement, but was recently confirmed to exhibit electric conductivity by electron doping. The C12A7 electride has relatively low-work function (2.9 eV). In this paper, the negative muonium production measurement with several materials including a C12A7 electride film will be presented. Measured production rate of the Mu were 10
/s for all the Al, electride, and SUS target. Significant enhancement on electride target was not observed, thus it is presumed that the surface condition should be more carefully treated. There was no material dependence of the Mu averaged energy: it was 0.20.1keV.
Nakazawa, Yuga*; Bae, S.*; Choi, H.*; Choi, S.*; Iijima, Toru*; Iinuma, Hiromi*; Kawamura, Naritoshi*; Kitamura, Ryo; Kim, B.*; Ko, H. S.*; et al.
Nuclear Instruments and Methods in Physics Research A, 937, p.164 - 167, 2019/09
Times Cited Count：3 Percentile：28.10(Instruments & Instrumentation)A muon linac is under development for the precise measurement of the muon anomalous magnetic moment (
-2) and electric dipole moment (EDM) with a reaccelerated thermal muon beam. An H source driven by an ultraviolet light has been developed for the muon acceleration experiment. Prior to the acceleration experiment, a beamline commissioning was performed using this H beam, since the accelerated muon intensity is very low. We successfully measured the magnetic rigidity, which is essential for identifying the accelerated muons. This H source is capable of utilizing as a general-purpose beam source for other beamline.
Yotsuzuka, Mai*; Iijima, Toru*; Iinuma, Hiromi*; Inami, Kenji*; Otani, Masashi*; Kawamura, Naritoshi*; Kitamura, Ryo; Kondo, Yasuhiro; Saito, Naohito; Shimomura, Koichiro*; et al.
Proceedings of 16th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.814 - 817, 2019/07
The J-PARC E34 experiment aims to measure the muon anomalous magnetic moment and the electric dipole moment with a high precision. In this experiment, thermal muonium is produced and ionized by laser resonance to generate ultra-slow muons, which are then accelerated in a multistage muon linac. In order to satisfy the experimental requirements, suppression of the emittance growth during the acceleration is necessary. Because the main cause of the emittance growth is beam mismatching between the accelerating stages, the transverse and longitudinal beam monitoring is important. The longitudinal beam monitor has to measure the bunch length with the resolution equivalent to tens of picoseconds, which is 1% of the acceleration phase of 324 MHz. In addition, it should be sensitive to single muon because the beam intensity is limited during the commissioning phase. To realize above requirements, we are developing a longitudinal beam monitor with a micro channel plate, and the test bench to evaluate the monitor performance. So far, the time resolution of the beam monitor was obtained to be 65 ps in RMS including the jitter on the test bench. We also succeeded in measuring the longitudinal bunch size of the muon beam accelerated by RFQ using the beam monitor. In this paper, the results of the performance evaluation for this beam monitor are reported.
Sue, Yuki*; Iijima, Toru*; Inami, Kenji*; Yotsuzuka, Mai*; Iinuma, Hiromi*; Nakazawa, Yuga*; Otani, Masashi*; Kawamura, Naritoshi*; Shimomura, Koichiro*; Futatsukawa, Kenta*; et al.
Proceedings of 16th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.55 - 60, 2019/07
The result of bunch size measurement of muon accelerated by RFQ up to 89 keV is presented in this paper. A four-stage muon linac for precise measurement of muon property is under construction in the J-PARC. The demonstration of the first muon RF acceleration with an RFQ linac was conducted and the transverse profile of the accelerated muons was measured in 2017. As one of the remaining issues for the beam diagnostic system, the longitudinal beam profile after the RFQ should be measured to match the profile to the designed acceptance of the subsequent accelerator. For this purpose, the new longitudinal beam monitor using the microchannel plate is under development. The time resolution of the monitor aims to be around 30 to 40 ps corresponding to 1% of a period of an operating frequency of the accelerator, which is 324 MHz. On November 2018, the bunch size of accelerated negative muonium ion of 89 keV with the RFQ was measured using this monitor at the J-PARC MLF. The measured bunch width is 
ns, which is consistent with the simulation.
Yotsuzuka, Mai*; Iijima, Toru*; Inami, Kenji*; Sue, Yuki*; Iinuma, Hiromi*; Nakazawa, Yuga*; Saito, Naohito; Hasegawa, Kazuo; Kondo, Yasuhiro; Kitamura, Ryo; et al.
Proceedings of 10th International Particle Accelerator Conference (IPAC '19) (Internet), p.2571 - 2574, 2019/06
The J-PARC E34 experiment aims to measure the muon anomalous magnetic moment and the electric dipole moment with a high precision. In this experiment, thermal muonium is produced and ionized by laser resonance to generate ultra-slow muons, which are then accelerated in a multistage muon linac. In order to satisfy the experimental requirements, suppression of the emittance growth during the acceleration is necessary. Because the main cause of the emittance growth is beam mismatching between the accelerating stages, the transverse and longitudinal beam monitoring is important. The longitudinal beam monitor has to measure the bunch length with the resolution equivalent to tens of picoseconds, which is 1% of the acceleration phase of 324 MHz. In addition, it should be sensitive to single muon because the beam intensity is limited during the commissioning phase. To realize above requirements, we are developing a longitudinal beam monitor with a micro channel plate, and the test bench to evaluate the monitor performance. So far, the time resolution of the beam monitor was obtained to be 65 ps in RMS including the jitter on the test bench. We also succeeded in measuring the longitudinal bunch size of the muon beam accelerated by RFQ using the beam monitor. Further improvement of the measurement system is needed to guarantee the required accuracy. In this paper, the results of the performance evaluation for this beam monitor are reported.
Sue, Yuki*; Iijima, Toru*; Inami, Kenji*; Yotsuzuka, Mai*; Futatsukawa, Kenta*; Kawamura, Naritoshi*; Mibe, Tsutomu*; Miyake, Yasuhiro*; Otani, Masashi*; Hasegawa, Kazuo; et al.
Proceedings of 10th International Particle Accelerator Conference (IPAC '19) (Internet), p.37 - 40, 2019/06
The result of bunch size measurement of muon accelerated by RFQ up to 89 keV is presented in this paper. A four-stage muon linac for precise measurement of muon property is under construction in the J-PARC. The demonstration of the first muon RF acceleration with an RFQ linac was conducted and the transverse profile of the accelerated muons was measured in 2017. As one of the remaining issues for the beam diagnostic system, the longitudinal beam profile after the RFQ should be measured to match the profile to the designed acceptance of the subsequent accelerator. For this purpose, the new longitudinal beam monitor using the microchannel plate is under development. The time resolution of the monitor aims to be around 30 to 40 ps corresponding to 1% of a period of an operating frequency of the accelerator, which is 324 MHz. On November 2018, the bunch size of accelerated negative muonium ion of 89 keV with the RFQ was measured using this monitor at the J-PARC MLF. The measured bunch width is ns, which is consistent with the simulation.
Abe, Mitsushi*; Bae, S.*; Beer, G.*; Bunce, G.*; Choi, H.*; Choi, S.*; Chung, M.*; da Silva, W.*; Eidelman, S.*; Finger, M.*; et al.
Progress of Theoretical and Experimental Physics (Internet), 2019(5), p.053C02_1 - 053C02_22, 2019/05
Times Cited Count：156 Percentile：99.31(Physics, Multidisciplinary)This paper introduces a new approach to measure the muon magnetic moment anomaly 
and the muon electric dipole moment (EDM) 
at the J-PARC muon facility. The goal of our experiment is to measure 
and using an independent method with a factor of 10 lower muon momentum, and a factor of 20 smaller diameter storage-ring solenoid compared with previous and ongoing muon g-2 experiments with unprecedented quality of the storage magnetic field. Additional significant differences from the present experimental method include a factor of 1000 smaller transverse emittance of the muon beam (reaccelerated thermal muon beam), its efficient vertical injection into the solenoid, and tracking each decay positron from muon decay to obtain its momentum vector. The precision goal for is a statistical uncertainty of 450 parts per billion (ppb), similar to the present experimental uncertainty, and a systematic uncertainty less than 70 ppb. The goal for EDM is a sensitivity of 
e
cm.
Otani, Masashi*; Sue, Yuki*; Fukao, Yoshinori*; Futatsukawa, Kenta*; Kawamura, Naritoshi*; Mibe, Tsutomu*; Miyake, Yasuhiro*; Shimomura, Koichiro*; Yamazaki, Takayuki*; Iijima, Toru*; et al.
Journal of Physics; Conference Series, 1067(5), p.052012_1 - 052012_7, 2018/09
Times Cited Count：1 Percentile：44.76(Physics, Particles & Fields)We have measured the muon beam profile after acceleration using a radio frequency quadrupole linac (RFQ). Positive muons are injected to an aluminum degrader and negative muoniums (Mu
) are generated. The generated Mus are extracted by an electrostatic lens and accelerated to 89 keV by the RFQ. The accelerated Mus are transported to a beam profile monitor (BPM) through a quadrupole magnet pair and a bending magnet. The BPM consists of a micro-channel plate, a phospher screen, and a CCD camera. Measured profile in the vertical direction is consistent to the simulation. This profile measurement is one of milestones for realizing a muon linac for measurement of the muon anomalous magnetic moment at the Japan Proton Accelerator Research Complex.
Kitamura, Ryo*; Otani, Masashi*; Fukao, Yoshinori*; Futatsukawa, Kenta*; Kawamura, Naritoshi*; Mibe, Tsutomu*; Miyake, Yasuhiro*; Yamazaki, Takayuki*; Kondo, Yasuhiro; Hasegawa, Kazuo; et al.
Proceedings of 15th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.239 - 243, 2018/08
Muon acceleration is an important technique in exploring the new frontier of physics. A new measurement of the muon dipole moments is planned in J-PARC using the muon linear accelerator. The low-energy (LE) muon source using the thin metal foil target and beam diagnostic system were developed for the world's first muon acceleration. Negative muonium ions from the thin metal foil target as the LE muon source was successfully observed. Also the beam profile of the LE positive muon was measured by the LE-dedicated beam profile monitor. The muon acceleration test using a Radio-Frequency Quadrupole linac (RFQ) is being prepared as the first step of the muon accelerator development. In this paper, the latest status of the first muon acceleration test is described.
Bae, S.*; Choi, H.*; Choi, S.*; Fukao, Yoshinori*; Futatsukawa, Kenta*; Hasegawa, Kazuo; Iijima, Toru*; Iinuma, Hiromi*; Ishida, Katsuhiko*; Kawamura, Naritoshi*; et al.
Physical Review Accelerators and Beams (Internet), 21(5), p.050101_1 - 050101_6, 2018/05
Times Cited Count：16 Percentile：75.24(Physics, Nuclear)Muons have been accelerated by using a radio-frequency accelerator for the first time. Negative muonium atoms (Mu), which are bound states of positive muons and two electrons, are generated from through the electron capture process in an aluminum degrader. The generated Mu's are initially electrostatically accelerated and injected into a radio-frequency quadrupole linac (RFQ). In the RFQ, the Mu's are accelerated to 89 keV. The accelerated Mu's are identified by momentum measurement and time of flight. This compact muon linac opens the door to various muon accelerator applications including particle physics measurements and the construction of a transmission muon microscope.
Sn strand during coolingSuwa, Tomone*; Hemmi, Tsutomu*; Saito, Toru*; Takahashi, Yoshikazu*; Koizumi, Norikiyo*; Luzin, V.*; Suzuki, Hiroshi; Harjo, S.
IEEE Transactions on Applied Superconductivity, 28(3), p.6001104_1 - 6001104_4, 2018/04
Times Cited Count：1 Percentile：6.81(Engineering, Electrical & Electronic)Ito, Daisuke*; Rivera, M. N.*; Saito, Yasushi*; Aoyagi, Mitsuhiro; Kamiyama, Kenji; Suzuki, Toru*
Proceedings of 17th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-17) (USB Flash Drive), 10 Pages, 2017/09
Nava, M.*; Ito, Daisuke*; Saito, Yasushi*; Aoyagi, Mitsuhiro; Kamiyama, Kenji; Suzuki, Toru*
Proceedings of 25th International Conference on Nuclear Engineering (ICONE-25) (CD-ROM), 5 Pages, 2017/07
Sn strands of CIC conductor using neutron diffractionHemmi, Tsutomu*; Harjo, S.; Kajitani, Hideki*; Suwa, Tomone*; Saito, Toru*; Aizawa, Kazuya; Osamura, Kozo*; Koizumi, Norikiyo*
IEEE Transactions on Applied Superconductivity, 27(4), p.4200905_1 - 4200905_5, 2017/06
Times Cited Count：2 Percentile：12.87(Engineering, Electrical & Electronic)Ito, Daisuke*; Nava, M.*; Saito, Yasushi*; Aoyagi, Mitsuhiro; Kamiyama, Kenji; Suzuki, Toru*
Proceedings of 2017 Japan-US Seminar on Two-Phase Flow Dynamics (JUS 2017), 4 Pages, 2017/06
Saito, Toru; Okubo, Toshikazu*; Izumi, Keisuke*; Okawa, Yoshinao*; Kobayashi, Norihiro*; Yamazaki, Toru; Kawano, Katsumi; Isono, Takaaki
Teion Kogaku, 50(8), p.400 - 408, 2015/08
Aramid fiber-reinforced plastic (AFRP) has been developed as a structural material that has the advantages of light weight and high strength. In this study, tensile tests were carried out to measure the tensile properties of AFRP rod on the market for reinforcement of concrete at room temperature, 77 K and 4.2 K. Especially at cryogenic temperatures, it is difficult to perform a tensile test of the bar because the specimen slips through the jig grip. To prevent the rod from slipping, tensile tests were carried out with some filling conditions. The applicable and appropriate tensile test conditions were established by modifying the jig grip, treating the surface of the rod and using cryogenic epoxy infill to grip the rod. They were more than 1100 MPa. Additionally, the AFRP rod included a temperature dependence in which the Young's modulus increased as the test temperature decreased. It was confirmed that the Young's modulus increased because aramid fiber was more dominant than epoxy.
Ozeki, Hidemasa; Saito, Toru; Kawano, Katsumi; Takahashi, Yoshikazu; Nunoya, Yoshihiko; Yamazaki, Toru; Isono, Takaaki
Physics Procedia, 67, p.1010 - 1015, 2015/07
Times Cited Count：4 Percentile：77.99(Physics, Applied)