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Okawa, Tomohiro; Ao, Hiroyuki; Sako, Hiroyuki; Ueno, Akira; Hasegawa, Kazuo; Ikegami, Masanori*
Proceedings of 2007 Particle Accelerator Conference (PAC '07) (Internet), p.3324 - 3326, 2007/08
In the beam commissioning of J-PARC linac, we use three simulations codes for accelerator modeling, which includes TRACE3D, XAL online model and PARMILA. TRACE3D is mainly used to determine the initial configuration for quadrupole magnets, XAL online model is mainly used for the transverse matching and orbit correction and PARMILA is mainly used to model phase-slip effects in a phase-scan tuning. We have compared the modeling with the experimental results obtained in the beam commissioning to date, where a basic agreement has been confirmed between the modeling and the actual beam behavior.
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.
Schnase, A.; Hasegawa, Katsushi; Nomura, Masahiro; Tamura, Fumihiko; Yamamoto, Masanobu; Anami, Shozo*; Ezura, Eiji*; Hara, Keigo*; Omori, Chihiro*; Takagi, Akira*; et al.
Proceedings of 2007 Particle Accelerator Conference (PAC '07) (Internet), p.2131 - 2133, 2007/08
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.
Kobayashi, Tetsuya; Chishiro, Etsuji; Hori, Toshihiko; Suzuki, Hiroyuki; Yamazaki, Masayoshi; Anami, Shozo*; Fang, Z.*; Fukui, Yuji*; Kawamura, Masato*; Michizono, Shinichiro*; et al.
Proceedings of 2007 Particle Accelerator Conference (PAC '07) (Internet), p.2128 - 2130, 2007/08
High power operation of all the RF systems of J-PARC linac was started for the cavity conditioning in October 2006. Twenty 324-MHz klystrons have supplied the power to the accelerating cavities successfully, and the beam commissioning was started in November 2006. The RF drive and control systems are working well, and required stability is satisfied.
Fang, Z.*; Anami, Shozo*; Michizono, Shinichiro*; Yamaguchi, Seiya*; Kobayashi, Tetsuya; Suzuki, Hiroyuki
Proceedings of 2007 Particle Accelerator Conference (PAC '07) (Internet), p.2101 - 2103, 2007/08
The commissioning of the J-PARC 181-MeV proton linac was started from October of 2006. The RF sources of the linac consist of 4 solid-state amplifiers and 20 klystrons. In each RF source, the RF fields are controlled by a digital RF feedback (FB) system installed in a compact PCI (cPCI) to realize the accelerating field stability of 
1% in amplitude and 1 degree in phase. In this paper the performance of the RF feedback control systems will be reported in detail.
Sasaki, Shigemi*; McNulty, I.*; Shimada, Taihei
Proceedings of 2007 Particle Accelerator Conference (PAC '07) (Internet), p.1142 - 1144, 2007/06
Photons that carry orbital angular momentum are of great interest to the optics communities. This property of photon beams was recently demonstrated in the X-ray regime and may be useful to probe angular momentum in matter. However, by comparison to the visible light, it is difficult to fabricate efficient achromatic optics to generate these optical modes in X-rays. In spite of these inconveniences, there has been no investigation of the possibility of using a synchrotron light source to directly generate an X-ray beam with transverse optical modes. In this paper, we investigate use of an APPLE-type undulator for generating L-G and H-G mode beams. We find that the 2nd harmonic radiation in the circular mode corresponds to an LG beam with 
=1, and the 2nd harmonic in the linear mode corresponds to an HG beam with =1. The combination of an APPLE device and monochromator optics may provide an opportunity for a new type of experimental research in the synchrotron radiation community.
Morishita, Takatoshi; Asano, Hiroyuki; Ueno, Akira; Hasegawa, Kazuo; Ikegami, Masanori*
Proceedings of 2007 Particle Accelerator Conference (PAC '07) (Internet), p.1520 - 1522, 2007/06
J-PARC linear accelerator components have been installed. Precise alignment of the accelerator components is essential for high quality beam acceleration. Before the beam commissioning, a precise survey for alignment has been performed. The reference points on the tunnel wall were set up to built a survey network. Based on the survey results, the magnets in the straight section were re-aligned finely. Then, the results of the displacement are confirmed to be tolerable for the beam commissioning.
Morishita, Takatoshi; Asano, Hiroyuki; Ito, Takashi; Ueno, Akira; Hasegawa, Kazuo; Naito, Fujio*; Takasaki, Eiichi*; Tanaka, Hirokazu*; Yoshino, Kazuo*; Ikegami, Masanori*
Proceedings of 2007 Particle Accelerator Conference (PAC '07) (Internet), p.1523 - 1525, 2007/06
J-PARC linear accelerator components have been installed. The required alignment accuracy in the J-PARC linac is 0.1mm in transverse direction. In the DTL/SDTL section, the fine alignment was carried out by using an optical alignment telescope along with the cavity installation. The displacement of the DTL by the unit tank connection was monitored by a laser tracker to obtain the tolerable displacement between unit tanks. The heights of cavities and magnets were compensated form the unequal ground movement of the linac tunnel. Finally, all the cavities and magnets are aligned within the tolerable alignment error.
Hasegawa, Kazuo
Proceedings of 2007 Particle Accelerator Conference (PAC '07) (Internet), p.2619 - 2623, 2007/06
The J-PARC (Japan Proton Accelerator Research Complex)is a multi purpose facility with 1 MW class proton beam power. The J-PARC comprises a linac, a 3 GeV rapid-cycling synchrotron (RCS), a 50 GeV main ring synchrotron (MR) and experimental facilities. The energy of the linac is reduced to 181 MeV for the time being, and it will be increased to 400 MeV in the near future. The 3 MeV RFQ, which is a front end of the linac, has been beam commissioned since November 2006, and we continue to work on the rest of the linac such as a 50 MeV DTL and a 181 MeV Separated-type DTL. The results and status of the J-PARC linac beam commissioning are presented.
Sawamura, Masaru; Furuya, Takaaki*; Sakanaka, Shogo*; Suwada, Tsuyoshi*; Takahashi, Takeshi*; Umemori, Kensei*; Sakai, Hiroshi*; Shinoe, Kenji*
Proceedings of 2007 Particle Accelerator Conference (PAC '07) (Internet), p.1022 - 1024, 2007/06
An eccentric-fluted beam pipe was proposed to damp quadrupole modes. The eccentric-flute acts as a mode converter from quadrupole to dipole. Optimized parameters permit to damp both degenerate modes of quadrupole with the eccentric-flute. External Q-values measured with a low power model agreed well with those calculated with MAFIA.
Sawamura, Masaru
Proceedings of 2007 Particle Accelerator Conference (PAC '07) (Internet), p.4060 - 4062, 2007/06
The offset beam from the axis induces the HOMs in the cavities. These HOMs in superconducting cavities are usually damped by HOM couplers to suppress the beam instability. The induced HOM power is proportional to the beam offset and can be used to measure the beam position inside the cavity. The steering magnet is installed to the JAEA superconducting ERL-FEL to vary the beam position. The HOM power from the HOM coupler with various beam position is measured. The result of the beam test is presented.
Tamura, Fumihiko; Schnase, A.; Nomura, Masahiro; Yamamoto, Masanobu; Hasegawa, Katsushi; Yoshii, Masahito*; Anami, Shozo*; Ezura, Eiji*; Hara, Keigo*; Omori, Chihiro*; et al.
Proceedings of 2007 Particle Accelerator Conference (PAC '07) (Internet), p.2125 - 2127, 2007/06
Multi-turn injection using charge exchange is employed for the J-PARC Rapid Cycling Synchrotron (RCS). To reduce space charge effects, the bunching factor of the beam in the ring should be increased. Therefore the momentum-offset injection scheme is used. In each turn, the bunch trains from the linac are injected into the RF buckets with a momentum offset. The bunch train is called the "intermediatepulse". The intermediate pulses are generated in the low energy section of the linac by the RF chopper and pre-chopper. Since the pulses must be synchronized to the RF voltage in the ring, the timing signals for the choppers are generated by the low-level RF (LLRF) system of the RCS. The chopper pulses are sent via optical cables. We developed the chopper timingmodule. We describe the details of the hardware.
Ito, Takashi; Asano, Hiroyuki; Morishita, Takatoshi; Ao, Hiroyuki; Tanaka, Hirokazu*; Naito, Fujio*; Kato, Takao*; Takasaki, Eiichi*
Proceedings of 2007 Particle Accelerator Conference (PAC '07) (Internet), p.1517 - 1519, 2007/06
The high-power conditioning of the three DTL tanks for the J-PARC has been started in October 2006. The design rf peak-power levels for beam acceleration of the tanks are about 1.1MW (DTL1), 1.2MW (DTL2) and 1.0MW (DTL3), respectively. As a result of the conditioning, we have achieved that the rf power levels are about 1.3MW, 1.45MW and 1.23MW of which are 1.2 times the power levels of the desired one (the pulse length is 650
s and the pulse repetition is 25Hz). During the linac beam commissioning, the DTLs can keep the required rf power stable now.
