Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Ca cast doubt on a doubly magic 
CaChen, S.*; Browne, F.*; Doornenbal, P.*; Lee, J.*; Obertelli, A.*; Tsunoda, Yusuke*; Otsuka, Takaharu*; Chazono, Yoshiki*; Hagen, G.*; Holt, J. D.*; et al.
Physics Letters B, 843, p.138025_1 - 138025_7, 2023/08
Times Cited Count：9 Percentile：89.00(Astronomy & Astrophysics)Gamma decays were observed in 
Ca and 
Ca following quasi-free one-proton knockout reactions from 
Sc. For Ca, a 
ray transition was measured to be 1456(12) keV, while for Ca an indication for a transition was observed at 1115(34) keV. Both transitions were tentatively assigned as the 
decays. A shell-model calculation in a wide model space with a marginally modified effective nucleon-nucleon interaction depicts excellent agreement with experiment for 
level energies, two-neutron separation energies, and reaction cross sections, corroborating the formation of a new nuclear shell above the N = 34 shell. Its constituents, the 
and 
orbitals, are almost degenerate. This degeneracy precludes the possibility for a doubly magic Ca and potentially drives the dripline of Ca isotopes to 
Ca or even beyond.
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, 2022/10
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.
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.
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.
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.
Takeuchi, Yusuke*; Tojo, Junji*; Nakazawa, Yuga*; Kondo, Yasuhiro; Kitamura, Ryo; Morishita, Takatoshi; Cicek, E.*; Ego, Hiroyasu*; Futatsukawa, Kenta*; Kawamura, Naritoshi*; et al.
Proceedings of 13th International Particle Accelerator Conference (IPAC 22) (Internet), p.1534 - 1537, 2022/06
The muon g-2/EDM experiment is under preparation at Japan Proton Accelerator Research Complex (J-PARC), and the muon linear accelerator for the experiment is being developed. A Disk-and-Washer (DAW) cavity will be used for the medium-velocity part of the accelerator, and muons will be accelerated from 
= 
= 0.3 to 0.7 with the operating frequency of 1.296 GHz. Machining, brazing, and low-power measurements of a prototype cell reflecting the design of the first tank of DAW were performed to identify fabrication problems. Several problems were identified, such as misalignment of washers during brazing, and some measures will be taken in the actual tank fabrication. In this paper, the results of the prototype cell fabrication will be reported.
-Orbital component in the Borromean nucleus 
BYang, Z. H.*; Kubota, Yuki*; Corsi, A.*; Yoshida, Kazuki; Sun, X.-X.*; Li, J. G.*; Kimura, Masaaki*; Michel, N.*; Ogata, Kazuyuki*; Yuan, C. X.*; et al.
Physical Review Letters, 126(8), p.082501_1 - 082501_8, 2021/02
Times Cited Count：61 Percentile：95.90(Physics, Multidisciplinary)A quasifree (
,
) experiment was performed to study the structure of the Borromean nucleus B, which had long been considered to have a neutron halo. By analyzing the momentum distributions and exclusive cross sections, we obtained the spectroscopic factors for 
and 
orbitals, and a surprisingly small percentage of 9(2)% was determined for . Our finding of such a small component and the halo features reported in prior experiments can be explained by the deformed relativistic Hartree-Bogoliubov theory in continuum, revealing a definite but not dominant neutron halo in B. The present work gives the smallest - or -orbital component among known nuclei exhibiting halo features and implies that the dominant occupation of or orbitals is not a prerequisite for the occurrence of a neutron halo.
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：20.23(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.
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.
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.
Sueyoshi, Tetsuro*; Kotaki, Tetsuya*; Furuki, Yuichi*; Uraguchi, Yusei*; Kai, Takashi*; Fujiyoshi, Takanori*; Shimada, Yusuke*; Yasuda, Kazuhiro*; Ishikawa, Norito
IEEE Transactions on Applied Superconductivity, 25(3), p.6603004_1 - 6603004_4, 2015/06
Times Cited Count：12 Percentile：50.69(Engineering, Electrical & Electronic)To investigate the effect of discontinuity of 1-D pinning centers on the flux pinning in a wide range of magnetic field directions, discontinuous columnar defects (CDs) and continuous CDs were formed in GdBCO coated conductors using Xe-ion irradiations with 80 and 270 MeV, respectively. An overall shift upward in Jc, for the 80-MeV-irradiated sample compared to the 270-MeV-irradiated one, can be observed in every direction of magnetic field, which is more remarkable as temperature decreases. This implies a synergetic effect of the pinning interaction between the linearity and the discontinuity for the discontinuous CDs.
Li, T.*; Garg, U.*; Liu, Y.*; Marks, R.*; Nayak, B. K.*; Madhusudhana Rao, P. V.*; Fujiwara, Mamoru*; Hashimoto, Hisanobu*; Nakanishi, Kosuke*; Okumura, Shun*; et al.
Physical Review C, 81(3), p.034309_1 - 034309_11, 2010/03
Times Cited Count：118 Percentile：97.60(Physics, Nuclear)
O(
) reaction at forward angles and structure of the spin-dipole resonancesKawabata, Takahiro*; Ishikawa, Takatsugu*; Ito, M.*; Nakamura, M.*; Sakaguchi, Harutaka*; Takeda, H.*; Taki, T.*; Uchida, Makoto*; Yasuda, Yusuke*; Yosoi, Masaru*; et al.
Physical Review C, 65(6), p.064316_1 - 064316_12, 2002/06
Times Cited Count：20 Percentile：69.49(Physics, Nuclear)no abstracts in English
Ito, M.*; Sakaguchi, Harutaka*; Ishikawa, Takatsugu*; Kawabata, Takahiro*; Murakami, Tetsuya*; Takeda, H.*; Taki, T.*; Tsukahara, N.*; Uchida, Makoto*; Yasuda, Yusuke*; et al.
Nuclear Physics A, 687(1-2), p.52c - 57c, 2001/04
no abstracts in English
O (p,p') experimentKawabata, Takahiro*; Akimune, Hidetoshi*; Fujimura, Hisako*; Fujita, Hirohiko*; Fujita, Yoshitaka*; Fujiwara, Mamoru; Hara, Keigo*; Hatanaka, Kichiji*; Hosono, K.*; Ishikawa, Takatsugu*; et al.
Nuclear Instruments and Methods in Physics Research A, 459(1-2), p.171 - 176, 2001/02
Times Cited Count：18 Percentile：75.70(Instruments & Instrumentation)no abstracts in English
Goke, Mitsuo*; Okihara, Mitsunobu*; Maemura, Tsuneyuki*; Yasuda, Ryo*; Matsui, Hiroya; Ozaki, Yusuke; Mochizuki, Akihito
no journal, ,
We performed the numerical simulation to simulate the long term change in geological environment under open drift condition. We developed the conceptual model for the purpose and performed the geomechanical and hydrological simulation with the models considering the existence of excavation damaged zone and tunnel support. The geomechanical simulation results suggested that the deformation for long term is so slight that the excavation damaged zone does not enlarge. The hydrological simulation considering the degassing predicted the expansion of the unsaturated zone in the high pore pressure domain.
Kaneya, Yusuke*; Sato, Tetsuya; Asai, Masato; Tsukada, Kazuaki; Toyoshima, Atsushi; Sato, Nozomi; Oe, Kazuhiro; Miyamoto, Yutaka; Yasuda, Kenichiro; Ninomiya, Kazuhiko; et al.
no journal, ,
We have measured radioactivities in soils contaminated by the severe accident of Fukushima Daiichi Nuclear Power Plant. The soil samples were taken at the 83 points distributed around the north area of Ibaraki prefecture. Radioactivities in the soils were measured by -ray spectrometry, and distributions of 
Cs in this area were clarified. The highest radioactivity of 130 kBq/m
of 
Cs was observed at the boundary among Tochigi, Fukushima, and Ibaraki prefecture, while it was about 3 kBq/m at the center of Ibaraki.
Ota, Shuya*; Yasuda, Nakahiro*; Sihver, L.*; Kodaira, Satoshi*; Ideguchi, Yusuke*; Hasebe, Nobuyuki*
no journal, ,
Projectile charge-changing cross sections for nuclei in galactic cosmic rays (GCRs) on hydrogen play essentially important roles for the study of origin and source composition of GCRs. Previous experimental and theoretical works done so far made much progress on those cross sections. However, there are still uncertainties in much of the cross section data, and therefore the present knowledge of cross sections has not led to successful determination of the GCR source composition. To improve the uncertainties, a novel measurement system of projectile charge-changing cross section using CR-39 plastic nuclear track detectors with excellent position and nuclear charge resolutions has been developed. We carried out measurements of total and partial charge-changing cross sections for Fe and Mg on 
and 
targets at 0.1 to 1 GeV/n using the method.
Chiba, Satoshi; Ota, Shuya*; Yasuda, Nakahiro*; Sihver, L.*; Kodaira, Satoshi*; Ideguchi, Yusuke*; Hasebe, Nobuyuki*
no journal, ,
no abstracts in English
Oda, Shoji*; Yasuda, Takako*; Hibi, Yusuke*; Asaka, Tomomi*; Ikeda, Hiroko; Muto, Yasuko*; Yokota, Yuichiro; Sakashita, Tetsuya; Suzuki, Michiyo; Funayama, Tomoo; et al.
no journal, ,
We have developed a new irradiation protocol for tissue specific irradiation to living embryo and adult medaka, 
. In the study, a testis of p53 knockout fish were irradiated with multi-shots of microbeam. Less numbers of testis-ova were induced in the in p53- lacking testis 1 week after the irradiation compared to whole body irradiated testis. Specific irradiation of microbeam onto the right (or left) lobe of the optic tectum in medaka embryos of 2 days post fertilization ectopically induced apoptotic cells in the body trunk and the tail in addition to the irradiated position. The systemic effects as endocrine system, autonomic nervous system and immunity reactions occur in adult medaka and these results suggested that the systemic effects might be functional even in developing embryos.
