Orlandi, R.; Makii, Hiroyuki; Nishio, Katsuhisa; Hirose, Kentaro; Asai, Masato; Tsukada, Kazuaki; Sato, Tetsuya; Ito, Yuta; Suzaki, Fumi; Nagame, Yuichiro*; et al.
Physical Review C, 106(6), p.064301_1 - 064301_11, 2022/12
Yan, S. Q.*; Li, X. Y.*; Nishio, Katsuhisa; Lugaro, M.*; Li, Z. H.*; Makii, Hiroyuki; Pignatari, M.*; Wang, Y. B.*; Orlandi, R.; Hirose, Kentaro; et al.
Astrophysical Journal, 919(2), p.84_1 - 84_7, 2021/10
Allenspach, S.*; Biffin, A.*; Stuhr, U.*; Tucker, G. S.*; Kawamura, Seiko; Kofu, Maiko; Voneshen, D. J.*; Boehm, M.*; Normand, B.*; Laflorencie, N.*; et al.
Physical Review Letters, 124(17), p.177205_1 - 177205_7, 2020/05
Yan, S. Q.*; Li, Z. H.*; Wang, Y. B.*; Nishio, Katsuhisa; Lugaro, M.*; Karakas, A. I.*; Makii, Hiroyuki; Mohr, P.*; Su, J.*; Li, Y. J.*; et al.
Astrophysical Journal, 848(2), p.98_1 - 98_8, 2017/10
Kikkawa, Takashi*; Shen, K.*; Flebus, B.*; Duine, R. A.*; Uchida, Kenichi*; Qiu, Z.*; Bauer, G. E. W.*; Saito, Eiji
Physical Review Letters, 117(20), p.207203_1 - 207203_6, 2016/11
Yan, S. Q.*; Li, Z. H.*; Wang, Y. B.*; Nishio, Katsuhisa; Makii, Hiroyuki; Su, J.*; Li, Y. J.*; Nishinaka, Ichiro; Hirose, Kentaro; Han, Y. L.*; et al.
Physical Review C, 94(1), p.015804_1 - 015804_5, 2016/07
Althammer, M.*; Meyer, S.*; Nakayama, Hiroyasu*; Schreier, M.*; Altmannshofer, S.*; Weiler, M.*; Huebl, H.*; Geprgs, S.*; Opel, M.*; Gross, R.*; et al.
Physical Review B, 87(22), p.224401_1 - 224401_15, 2013/06
We experimentally investigate and quantitatively analyze the spin Hall magnetoresistance (SMR) effect in ferromagnetic insulator (FI)/Pt and FI/nonmagnetic metal/Pt hybrid structures. For the FI, we use either YIG, nickel ferrite, or magnetite and for the nonmagnet, Cu or Au. The SMR is theoretically ascribed to the combined action of spin Hall and inverse spin Hall effect in the Pt top layer. It therefore should characteristically depend upon the orientation of the magnetization in the adjacent ferromagnet and prevail even if an additional, nonmagnetic metal layer is inserted between Pt and the ferromagnet. Our experimental data corroborate these theoretical conjectures. Using the SMR theory to analyze our data, we extract the spin Hall angle and the spin diffusion length in Pt. For a spin-mixing conductance of m, we obtain a spin Hall angle of 0.11 0.08 and a spin diffusion length of (1.5 0.5) nm for Pt in our samples.
He, C.*; Shen, S.*; Wen, S.*; Zhu, L.*; Wu, X.*; Li, G.*; Zhao, Y.*; Yan, Y.*; Bai, Z.*; Wu, Y.*; et al.
Physical Review C, 87(3), p.034320_1 - 034320_10, 2013/03
Meier, D.*; Kuschel, T.*; Shen, L.*; Gupta, A.*; Kikkawa, Takashi*; Uchida, Kenichi*; Saito, Eiji; Schmalhorst, J.-M.*; Reiss, G.*
Physical Review B, 87(5), p.054421_1 - 054421_5, 2013/02
He, R.-H.*; Hashimoto, Makoto*; Karapetyan, H.*; Koralek, J. D.*; Hinton, J. P.*; Testaud, J. P.*; Nathan, V.*; Yoshida, Yoshiyuki*; Yao, H.*; Tanaka, Kiyohisa*; et al.
Science, 331(6024), p.1579 - 1583, 2011/03
The nature of the pseudogap phase of cuprate high-temperature superconductors is a major unsolved problem in condensed matter physics. We studied the commencement of the pseudogap state at temperature using three different techniques (angle-resolved photoemission spectroscopy, polar Kerr effect, and time-resolved reflectivity) on the same optimally doped Bi2201 crystals. We observed the coincident, abrupt onset at of a particle-hole asymmetric antinodal gap in the electronic spectrum, a Kerr rotation in the reflected light polarization, and a change in the ultrafast relaxational dynamics, consistent with a phase transition. Upon further cooling, spectroscopic signatures of superconductivity begin to grow close to the superconducting transition temperature (), entangled in an energy-momentum dependent manner with the preexisting pseudogap features, ushering in a ground state with coexisting orders.
Sako, Hiroyuki; Allen, C. K.*; Ikeda, Hiroshi*; Shen, G.*
IEEE Transactions on Nuclear Science, 57(3), p.1528 - 1535, 2010/06
A beam control system has been developed for the J-PARC linac to achieve strict design goals of beam performance and beam loss suppression in the high-intensity H-beams. An emerging concept of unified beam control has been adopted in the system, where a unified data source, standardized control units, aunified online model, and uniform high-level application frameworks have been designed and implemented. For precise beam controls, various beam tuning algorithms have been developed and tested. Design goals of beam performance, beam stability, and beam loss suppression have been achieved in the linac.
Shen, G.; Ikegami, Masanori*
Nuclear Instruments and Methods in Physics Research A, 598(2), p.361 - 371, 2009/01
In the beam commissioning of J-PARC linac, the RF set-point has been determined for 15 SDTL modules based on a beam experiment. In the beam-based tuning, a phase scan method is employed with the concept of phase signature matching. The obtained phase scan curve shows an excellent agreement with that from a numerical model, and the tuning accuracy of 1 deg in phase and 1 % in amplitude is achieved with a sufficient margin. In the phase scan tuning, the range of phase scanning is restricted to two critical regions to avoid the unfavorable influence from debunching. An analogous scheme has successfully been applied to the RF set-point tuning for bunchers and debunchers. The tuning goals for these cavities are set to 5 deg in phase and 5 % in amplitude. The tuning goal is expected to be met for those cavities, while the debuncher tuning is to be confirmed by directly monitoring the debuncher functions.
Yoshikawa, Hiroshi; Suzuki, Takahiro; Sakaki, Hironao; Ito, Yuichi; Kato, Yuko; Kawase, Masato; Sako, Hiroyuki; Shen, G.; Takahashi, Hiroki; Fukuta, Shimpei; et al.
Proceedings of 24th International Linear Accelerator Conference (LINAC 2008) (CD-ROM), p.52 - 54, 2009/00
LINAC of J-PARC began to operate in November, 2006, and a achieved an initial performance in January, 2007. Afterwards, the beam supply to RCS begins, and it is operating extremely with stability up to now. Here, the evaluation for comparison of the design and realities of architecture and performance of the LINAC control system are shown. Especially, the conceptual idea of function arrangement in the hierarchy of the control system architecture is shown. Now, the LINAC control system is in the second phase for the high power beam and reducing the beam loss, and the analysis of the system response identification for the high precision beam control is started.
Shen, G.; Ikegami, Masanori*
Chinese Physics C, 33(7), p.577 - 582, 2008/09
In the beam commissioning of J-PARC linac, the RF set-point tuning has been performed based on a phase scan method. In the tuning of DTL2 and DTL3, the phase scan curves show a remarkable agreement with the numerical model. In the DTL1 tuning, however, the phase scan curves show a notable discrepancy from the numerical model especially with the RF set-points far from its design value. A three-dimensional particle simulation has been conducted with IMPACT, and the generation of the low energy component and the severe filamentation are identified as the main sources of the observed discrepancy. To circumvent this difficulty, we have adopted two phase scan curves as the reference restricting the parameter range for the phase scan. The reference curves and scanning phase range are carefully determined to avoid the influence from the filamentation. The tuning goal of 1 in phase and 1% in amplitude is satisfied for DTL1 with the two-reference scheme.
Sato, Susumu; Igarashi, Zenei*; Tomisawa, Tetsuo; Miura, Akihiko; Ueno, Akira; Sako, Hiroyuki; Morishita, Takatoshi; Kondo, Yasuhiro; Shen, G.; Akikawa, Hisashi*; et al.
Proceedings of 5th Annual Meeting of Particle Accelerator Society of Japan and 33rd Linear Accelerator Meeting in Japan (CD-ROM), p.500 - 502, 2008/00
no abstracts in English
Sako, Hiroyuki; Sakaki, Hironao; Shen, G.; Takahashi, Hiroki; Yoshikawa, Hiroshi; Ikeda, Hiroshi*; Allen, C. K.*
Proceedings of International Conference on Accelerator and Large Experimental Physics Control Systems (ICALEPCS '07) (CD-ROM), p.698 - 700, 2007/10
A beam commissioning software system based on a relational database has been developed for J-PARC LINAC. A high level application framework with SAD script interperter, JCE was developed in Java. JCE and XAL developed in SNS has been used to write commissioning applications with functions of device control, online modeling and data analysis. A commissioning database system has been developed a base data source for commissioning tools.
Yoshikawa, Hiroshi; Sakaki, Hironao; Sako, Hiroyuki; Takahashi, Hiroki; Shen, G.; Kato, Yuko; Ito, Yuichi; Ikeda, Hiroshi*; Ishiyama, Tatsuya*; Tsuchiya, Hitoshi*; et al.
Proceedings of International Conference on Accelerator and Large Experimental Physics Control Systems (ICALEPCS '07) (CD-ROM), p.62 - 64, 2007/10
J-PARC is a large scale facility of the proton accelerators for the multi-purpose of scientific researches in Japan. This facility consists of three accelerators and three experimental stations. Now, J-PARC is under construction, and LINAC is operated for one year, 3GeV synchrotron has just started the commissioning in this October the 1st. The completion of this facility will be next summer. The control system of accelerators established fundamental performance for the initial commissioning. The most important requirement to the control system of this facility is to minimize the activation of accelerator devices. In this paper, we show that the performances of each layer of this control system have been achieved in the initial stage.
Akikawa, Hisashi*; Igarashi, Zenei*; Ikegami, Masanori*; Lee, S.*; Sato, Susumu; Shen, G.; Tomisawa, Tetsuo; Ueno, Akira
Proceedings of 2007 Particle Accelerator Conference (PAC '07) (Internet), p.1472 - 1474, 2007/08
Beam commissioning of J-PARC linac has been performed since November 2006. We have wire scanners in order to measure beam profile and perform transverse matching. Four wire scanners are installed at each matching section. We report the result of measurement of beam profile and matching.
Sato, Susumu; Tomisawa, Tetsuo; Sako, Hiroyuki; Shen, G.; Ueno, Akira; Akikawa, Hisashi*; Igarashi, Zenei*; Lee, S.*; Ikegami, Masanori*; Kamikubota, Norihiko*
Proceedings of 2007 Particle Accelerator Conference (PAC '07) (Internet), p.4072 - 4074, 2007/08
The beam commissioning of J-PARC LINAC has been started in November 2006. Beam Position Monitors (BPM's) which had been calibrated on the bench setup with a scanning wire, take beam-based-calibration method in order to enable the beam to pass at the centre of a quadrupole magnet (Q-magnet). The installed BPM's and their calibration methods are described.
Sako, Hiroyuki; Shen, G.; Ueno, Akira; Okawa, Tomohiro; Akikawa, Hisashi*; Ikegami, Masanori*
Proceedings of 4th Annual Meeting of Particle Accelerator Society of Japan and 32nd Linear Accelerator Meeting in Japan (CD-ROM), p.598 - 600, 2007/00
Transverse matching has been performed at J-PARC LINAC for matching sections at DTL-SDTL, S01A-S03B, MEBT2-ACS, and L3BT. Each matching section consists of 4 wire scanners and upstream 4 quadrupole magnets. From r.m.s. of beam profiles measured at 4 wire scanners, transverse Twiss parameters and emittance are fitted with Newton method based on an online model. Field of quadrupole magnets with matching conditions is calculated based on the model. At beam current of 5 mA and 25 mA, matching factors of within 4% were achieved.