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Journal Articles

Uniform beam distribution by nonlinear focusing forces

Yuri, Yosuke; Ishizaka, Tomohisa; Yuyama, Takahiro; Ishibori, Ikuo; Okumura, Susumu

Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.4149 - 4151, 2010/05

Journal Articles

Design and shielding of a beam line from ELENA to ATRAP using electrostatic quadrupole lenses and bends

Yuri, Yosuke; Lee, E.*

Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.4146 - 4148, 2010/05

Journal Articles

Design of an RF input coupler for the IFMIF/EVEDA RFQ linac

Maebara, Sunao

Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.3720 - 3722, 2010/05

Journal Articles

Control and pulsewidth-measurement of laser accelerated electron beams

Kotaki, Hideyuki; Hayashi, Yukio; Kawase, Keigo; Mori, Michiaki; Kando, Masaki; Homma, Takayuki; Koga, J. K.; Bulanov, S. V.

Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.3608 - 3610, 2010/05

Journal Articles

A Negative ion beam probe for diagnostics of a high intensity ion beam

Shinto, Katsuhiro; Wada, Motoi*; Kaneko, Osamu*; Tsumori, Katsuyoshi*; Nishiura, Masaki*; Sasao, Mamiko*; Kisaki, Masashi*

Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.999 - 1001, 2010/05

We propose a negative ion beam probe system as a new scheme to diagnose beam profile of high power positive ion beams. Two RF linacs of IFMIF have to drive the neutron source by providing continuous-wave (CW) positive deuterium ion beams with the intensity of 125 mA each at the beam energy of 40 MeV. During the CW beam operations, the extreme intensity of the beam and the severe radiation levels make the beam diagnostics with conventional techniques in the transport lines terribly difficult. A beam of negative ions liable to lose the additional electron at the occasion of impact with a high energy particle can work as a probe to measure the positive ion beam profile. On possible configuration to achieve high intensity beam profile measurement is to inject a negative ion probe beam into the target beam perpendicularly, and measure the attenuation of the negative ion beam by beam-beam interaction at each position. We have started an experimental study for the proof-of-principle of the new beam profile monitoring system. The paper presents the status quo of this beam profile monitor system development and the prospects to apply the system to the IFMIF beam line controls.

Journal Articles

Present status of the MPS and TS for IFMIF/EVEDA accelerator

Takahashi, Hiroki; Kojima, Toshiyuki; Tsutsumi, Kazuyoshi; Narita, Takahiro; Sakaki, Hironao; Maebara, Sunao

Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.2695 - 2697, 2010/05

Control System for IFMIF accelerators consists of the six subsystems; Central Control System (CCS), Local Area Network (LAN), Personnel Protection System (PPS), Machine Protection System (MPS), Timing System (TS) and Local Control System (LCS). The subsystems have been designed and their test benches been fabricated at JAEA. The IFMIF accelerator prototype provides a deuteron beam with the power more than 1 MW, which is as same as that in cases of J-PARC and SNS. In the control system, MPS and TS with high performance and precision are strongly required to avoid the radio-activation of the accelerator components. The prototypes of the MPS and TS are testing in conjunction with the injector test starting at CEA/Saclay from autumn in 2010. These results will feedback the design and the fabrication of the control components. This paper presents the development status of the TS modules and EPICS drivers for TS and MPS, and the prospects to apply them to the Injector test.

Journal Articles

Application of digital narrow band noise to J-PARC Main Ring

Schnase, A.; Tamura, Fumihiko; Koseki, Tadashi*; Tomizawa, Masahito*; Toyama, Takeshi*; Yoshii, Masahito*; Omori, Chihiro*; Nomura, Masahiro; Yamamoto, Masanobu; Toda, Makoto*; et al.

Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.1446 - 1448, 2010/05

Journal Articles

Dual-harmonic phase control in the J-PARC RCS

Tamura, Fumihiko; Schnase, A.; Yoshii, Masahito*; Omori, Chihiro*; Yamamoto, Masanobu; Nomura, Masahiro; Toda, Makoto*; Suzuki, Hiromitsu; Shimada, Taihei; Hara, Keigo*; et al.

Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.1443 - 1445, 2010/05

The wide-band RF cavities in the J-PARC RCS are operated in the dual-harmonic operation, in which each single cavity is driven by a superposition of the fundamental and the second harmonic RF signals. By the dual-harmonic operation large amplitude second harmonic signals for the bunch shape manipulation are generated without extra cavities. The phase control of the second harmonic RF is a key for the bunch shape manipulation. The fundamental RF signal is controlled by the phase feedback loop to damp the dipole oscillation. The second harmonic is locked to the phase of the vector-sum phase of the fundamental RF signals. We present the system detail and the performance in the beam operation of the RCS.

Journal Articles

Stabilization of laser accelerated electron bunch by the ionization-stage control

Mori, Michiaki; Kando, Masaki; Kotaki, Hideyuki; Hayashi, Yukio; Kawase, Keigo; Bulanov, S. V.; Ogura, Koichi; Pirozhkov, A. S.; Kondo, Kiminori; Sugiyama, Akira; et al.

Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.4062 - 4064, 2010/05

Journal Articles

Measurement of the parametric X-rays with the rocking curve method

Hayashi, Yukio; Kando, Masaki; Kotaki, Hideyuki; Kawase, Keigo; Homma, Takayuki; Bulanov, S. V.

Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.208 - 210, 2010/05

Parametric X-ray generation is one of the ways to obtain a monochromatic X-ray. The X-ray is generated through the interaction between high energy electrons and a crystal. The relationship between an X-ray wavelength and an angle of emission is followed by the Bragg condition. Therefore the monochromatic energy of the X-ray can be varied continuously by rotating the crystal. This tunability of X-ray wavelength is suitable for various applications. Here, we have measured 10 keV parametric X-rays with applying a rocking curve method. In this scheme, a large number of parametric X-rays are detected simultaneously. This enables us to find and tune the parametric X-ray quickly. As a result, we could find the sharp peak from this method with the Microtron accelerator at JAEA and a Si crystal. Since the peak angle is consistent to the Bragg condition for the 10 keV parametric X-ray generation, we think 10 keV photons have been generated through the parametric X-ray mechanism.

Journal Articles

The Data acquisition system of beam position monitors in J-PARC main ring

Hatakeyama, Shuichiro; Hayashi, Naoki; Arakawa, Dai*; Hashimoto, Yoshinori*; Hiramatsu, Shigenori*; Odagiri, Junichi*; Sato, Kenichiro*; Tejima, Masaki*; Tobiyama, Makoto*; Toyama, Takeshi*; et al.

Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.2698 - 2700, 2010/05

The Data Acquisition System of Beam Position Monitors (BPMs) in J-PARC Main Ring are consist of 186 Linux-based Data Processing Circuits (BPMCs) and 12 EPICS IOCs. They are important tool to see the COD and turn-by-turn beam positions. This report describes the process of the data reconstruction which include how the various calibration constants are applied.

Journal Articles

Status and progress of the J-PARC 3-GeV RCS

Kinsho, Michikazu

Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.627 - 629, 2010/05

The J-PARC 3-GeV rapid cycling synchrotron (RCS) has been operated for the neutron and MLF users program from December 23rd, 2008. The RCS operations not only in support of the MLF but also were providing beam to support commissioning of the MR. In parallel we are challenging to realize higher beam power operations with better stability. Before scheduled maintenance last summer beam power was limited by the front end of about 20 kW, after that maintenance the RCS has been operated the beam power of more than 100 kW for MLF users. After beam deliver operation to the MR and MLF, while the priority has been given to their beam tuning, the RCS also continues further beam studies toward higher beam intensity. On December 7th, 2009, the RCS achieved the beam power of more than 300 kW to the neutron production target with 25 Hz. This presentation will concentrate itself on the outcome of the J-PARC RCS commissioning program, including the discussion on the issues of the high-power operation.

Journal Articles

Intrabeam scattering at low temperature range

Yu, P.*; He, Z.*; Wei, J.*; Sessler, A. M.*; Okamoto, Hiromi*; Yuri, Yosuke

Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.1943 - 1945, 2010/05

Journal Articles

High-voltage test of a 500-kV photocathode DC gun for the ERL light sources in Japan

Nagai, Ryoji; Hajima, Ryoichi; Nishimori, Nobuyuki; Muto, Toshiya*; Yamamoto, Masahiro*; Honda, Yosuke*; Miyajima, Tsukasa*; Kuriki, Masao*; Iijima, Hokuto*; Kuwahara, Makoto*; et al.

Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.2341 - 2343, 2010/05

A 500-kV, 10-mA photocathode DC gun has been developed in a collaboration effort of JAEA, KEK, Hiroshima University and Nagoya University. We have utilized a segmented cylindrical ceramic insulator and guard-ring electrodes to prevent any damage to the insulator from electrons emitted by the support-rod electrode. The high-voltage test of the gun has been successfully done with up to 550 kV. The cathode electrode, anode electrode, and beam line apparatuses are now under fabrication. A beam test of the gun will be started soon. The high-voltage test and up-to-date status of the gun development will be presented in detail.

Journal Articles

Beam loss of J-PARC rapid cycling synchrotron at several hundred kW operation

Yamamoto, Kazami; Hayashi, Naoki; Hotchi, Hideaki; Saha, P. K.; Harada, Hiroyuki; Yoshimoto, Masahiro; Saeki, Riuji; Hatakeyama, Shuichiro

Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.2842 - 2844, 2010/05

A 3GeV Rapid-Cycling Synchrotron (RCS) in Japan Proton Accelerator Research Complex (J-PARC) has continuously provided more than 100kW proton beam to the Neutron target since October 2009. And we also successfully accelerated 300kW beam for one hour on December 10th by way of trial. We found some problems through these experiences. We report those problems and the residual dose in such high intensity operation.

Journal Articles

Status of the J-PARC RFQ

Hasegawa, Kazuo; Kobayashi, Tetsuya; Kondo, Yasuhiro; Morishita, Takatoshi; Oguri, Hidetomo; Hori, Yoichiro*; Kubota, Chikashi*; Matsumoto, Hiroshi*; Naito, Fujio*; Yoshioka, Masakazu*

Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.621 - 623, 2010/05

The J-PARC RFQ accelerates a negative hydrogen beam from 50 keV to 3 MeV. Beam commissioning of the J-PARC linac started in November 2006 and the linac has delivered beams to the 3 GeV synchrotron since September 2007. Trip rates of the RFQ, however, unexpectedly increased in September 2008. We tried to recover by tender conditioning, improvement of vacuum properties, etc. User operations for the Material and Life Experimental Facilities were successfully carried out at 20 kW in June 2009, and the beam power was increased to 120 kW in November. The high power operation at 300 kW for one hour was also demonstrated. Status and improvement of the J-PARC RFQ are presented.

Journal Articles

Condition of MA cores in the RF cavities of J-PARC synchrotrons after several years of operation

Nomura, Masahiro; Schnase, A.; Shimada, Taihei; Suzuki, Hiromitsu; Tamura, Fumihiko; Yamamoto, Masanobu; Ezura, Eiji*; Omori, Chihiro*; Hara, Keigo*; Hasegawa, Katsushi*; et al.

Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.3723 - 3725, 2010/05

We have been operating the RF cavities loaded with MA cores with a high field gradient of more than 20 kV/m since October 2007. We have been measuring the RF cavity impedance at the shutdown periods, and we detected the impedance reductions of RCS RF cavities on January and June 2009. Taking out the RF cavities from the beam line and opening them, we found that many of cores showed a buckling at the inner radius. We report the detail of condition of MA cores and the relation between the impedance reduction and core condition.

Journal Articles

First step analysis of hybrid type boron-doped carbon stripper foils for RCS of J-PARC

Yamazaki, Yoshio; Yoshimoto, Masahiro; Takeda, Osamu; Kinsho, Michikazu; Sugai, Isao*

Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.3924 - 3926, 2010/05

J-PARC requires thick carbon stripper foils to strip electrons from the H$$^-$$ beam supplied by the linac before injection into the Rapid Cycling Synchrotron (RCS). Foil thickness is about 200 $$mu$$ g/cm$$^2$$ corresponding to conversion efficiency of 99.7% from the primary H$$^-$$ beams of 181 MeV energy to H$$^+$$. For this purpose, we have successfully developed hybrid type thick boron-doped carbon (HBC) stripper foils, which showed a drastic improvement not only with respect to the lifetime, but also with respect to thickness reduction and shrinkage at high temperature during long beam irradiation. We started to study carbon stripper foils microscopically why carbon foils have considerable endurance for the beam impact by boron-doped. At first, we made a comparison between nominal carbon and HBC by the electric microscope and ion-induced analysis.

Journal Articles

Thermal characteristics of a new RFQ for J-PARC

Kondo, Yasuhiro; Hasegawa, Kazuo; Morishita, Takatoshi; Matsumoto, Hiroshi*; Naito, Fujio*

Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.780 - 782, 2010/05

A new RFQ for the J-PARC linac is under construction for more stable operation. The requirement of this RFQ is almost same as the now-operating one; the resonant frequency is 324 MHz, the injection energy is 50 keV, the extraction energy is 3 MeV, peak beam current is 30 mA, and RF duty is 1.5%. The resonant frequency tuning during operation will be done by adjusting the temperatures of the cooling waters. We investigate with FEM model both cases; change vane water temperature and change cavity-wall water temperature. The frequency range was 0.35 MHz and 0.28 MHz, respectively. However in the transient analysis, the frequency change of the vane case was smaller than that of the cavity-call case. In this paper, thermal characteristics of this RFQ and control system of the cooling water temperature is described.

Journal Articles

Beam based alignment of the beam position monitors at J-PARC RCS

Hayashi, Naoki; Harada, Hiroyuki; Hotchi, Hideaki; Toyama, Takeshi*; Tejima, Masaki*

Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.1005 - 1007, 2010/05

The J-PARC RCS is an M-Watt class rapid cycling synchrotron and, its physical aperture is designed to be more than 250mm in diameter. Even though its chamber size is such large, the BPM system gives precise data to determine beam optics parameters of the ring. For this purpose, relative positions and resolutions are important, however, for much higher intensity, the absolute beam position and accurate COD correction are indispensable. We have carefully installed the BPM, but it is also necessary to estimate its absolute position by using beam. If each QM could be controlled independently, the simple beam based alignment technique can be utilized, but it is not the case for RCS. There are seven families of QM, and only each family can be controlled at one time. We developed a new technique by expanding the simple method for the case of multiple QM focusing changed simultaneously, and applied to the J-PARC RCS. The paper describes this method and discussed about experimental results.

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