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Title |
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| MOPC133 |
Radiation Level in the J-PARC Rapid Cycling Synchrotron after First Study
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382 |
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- K. Yamamoto, N. Hayashi, S. Hiroki, R. Saeki
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
- K. Satoh, M. Tejima
KEK, Ibaraki
- T. Toyama
J-PARC, KEK & JAEA, Ibaraki-ken
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The 3GeV RCS (Rapid-Cycling Synchrotron) in J-PARC has been commissioned in October of 2007. The most important issue in the beam study is to reduce unnecessary beam loss and to keep the beam line clean for the sake of maintenance and upgrade of the machines. In order to achieve this purpose, we observed the beam loss monitors located around the RCS beam line and observed them for beam commissioning. We also investigated the residual dose of accelerator components during an interval of beam study. From these results, we found that beam loss points were the injection junction point, the branch of H0 dump and extraction line, transverse collimators, and dispersion maximum points in the arcs. Especially, the entrance of the primary collimator chamber and the current transformer of the H0 dump line were the most radio-activated points in the RCS. To make the best use of these results for beam commissioning, we managed to minimize the beam losses and succeeded in suppressing the residual dose to a level low enough to allows us to work close to those components.
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| TUPC034 |
Beam Instrumentations for the J-PARC RCS Commissioning
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1125 |
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- N. Hayashi, S. Hiroki, R. Saeki, K. Satou, R. Toyokawa, K. Yamamoto, M. Yoshimoto
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
- D. A. Arakawa, S. Hiramatsu, M. Tejima
KEK, Ibaraki
- S. Lee, T. Toyama
J-PARC, KEK & JAEA, Ibaraki-ken
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A 3-GeV Rapid-Cycling Synchrotron (RCS) of the Japan Proton Accelerator Research Complex (J-PARC) has been commissioned recently. During its beam commissioning, various beam diagnostic instrumentation has been used. The multi-wire profile monitor (MWPM) is used to establish injection and H0 dump line, which transports un-stripped H- or H0 beam to the dump. The electron catcher confirms that the beam hits a charge exchange carbon foil and the specified current monitor limits the beam current to the H0 dump. Single pass BPMs which detect linac frequency (324MHz) and ionization profile monitors (IPM) help to check the one pass orbit without circulation of the beam. The beam position monitor (BPM) can measure both COD and turn-by-turn position. Tune monitor system consists of exciter and its own BPM. The exciter shakes the beam and coherent oscillation is measured at BPM. Dedicated BPMs, Fast CT (FCT) and Wall Current Monitor (WCM) are used for RF feedback or feedforward control. It will describe the performance of each instruments and how they are contributed to the successful beam commissioning.
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| TUPC035 |
The Beam Position Monitor System of the J-PARC RCS
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1128 |
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- N. Hayashi, S. Hiroki, R. Saeki, K. Satou, R. Toyokawa, K. Yamamoto
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
- D. A. Arakawa, S. Hiramatsu, M. Tejima
KEK, Ibaraki
- S. Lee, T. Toyama
J-PARC, KEK & JAEA, Ibaraki-ken
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The Beam Position Monitor (BPM) system of the J-PARC RCS has been fabricated, installed and operated successfully during the beam commissioning. There are 54 BPMs around the ring and most of them are placed inside steering magnets. The BPM is electro static type and it has four electrodes. A pair of electrode gives a linear response with diagonal cut shape and they were calibrated before their installation. The signal processing unit, which is equipped with 14-bit 14MSPS ADC and 600MHz DSP, has been developed for the system. In order to measure small signal, especially during the initial phase of the commissioning, careful design also done for cabling. The paper presents the current performance of the system.
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| TUPC036 |
Multi-wire Profile Monitor for J-PARC 3GeV RCS
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1131 |
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- S. Hiroki, N. Hayashi, M. Kawase, F. Noda, P. K. Saha, H. Sako, H. Takahashi, A. Ueno
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
- Y. Arakida, S. Lee, T. Toyama
KEK, Ibaraki
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A set of six multi-wire profile monitors (MWPMs) has been installed in the injection line and the successive H0 dump line of the RCS (Rapid-Cycling Synchrotron), and contributed to the initial RCS commissioning for establishing an optimum injection orbit. The Au coated W wires (0.1 mm dia.) for the H- beam detection are fixed to a ceramic wind frame for two directions (horizontal and vertical with 17.7 o tilt, typically 51 wires with 2.9 mm or 9.5 mm distance), and the frame can be scanned for horizontal or vertical direction by using a stepping-motor driven actuator. A combination of the 17.7 o tilt wires and the precise scan function provides two step measurements, i.e. a rough profile is obtained only at one shot, and a detailed profile is measured for typically 101 shots (10 mm scan at 0.1 mm interval) thereafter. The beam induced charge signals are amplified by the instrumentation pre-amps located in a basement sub-tunnel at distances of 30-40 m from the frame through the shielded twisted pair cables. The signals are further transferred to the sample, hold and multiplex circuits at the ground floor. The digitized profile data are processed to the Gaussian fitting.
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| TUPC093 |
Beam Profile Monitor of the J-PARC 3GeV Rapid Cycling Synchrotron
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1275 |
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- K. Satou, N. Hayashi, R. Saeki, A. Ueno, K. Yamamoto
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
- H. Harada
Hiroshima University, Graduate School of Science, Higashi-Hiroshima
- S. Lee, T. Toyama
J-PARC, KEK & JAEA, Ibaraki-ken
- M. Tejima
KEK, Ibaraki
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To obtain high intensity (1MW) and large emittance (214 π mm mrad) beam profiles of the 3GeV Rapid Cycling Synchrotron (RCS) of the J-PARC, we have developed the ionization profile monitors (IPMs) with wide active aperture and high dynamic range. It has three Microchannel Plates (MCPs) with active area of 81*41mm for signal multiplication and read out devices, and magnet system to generate guiding fields to collect electrons. The wide active aperture of ±116mm is obtained by arranging the three MCPs perpendicular to the beam axis. Furthermore, the dynamic range of 104 level can be obtained by adjusting each bias voltage of the MCPs. The IPMs are now collecting ions without the guiding fields. The beam commissioning of the RCS has been in progress since last year. The horizontal and vertical profiles are of great help, particularly to check injection errors. At the conference, the present status of the IPM system and the latest beam profiles will be reported.
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| TUPP013 |
Synchronized Data Distribution and Acquisition System Using Reflective Memory for J-PARC 3GeV RCS
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1553 |
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- H. Takahashi, N. Hayashi
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
- M. Sugimoto
Mitsubishi Electric Control Software Corp, Kobe
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J-PARC 3GeV RCS inject the different parameter beam to each facilities, which are MLF and MR. Therefore, 3GeV RCS Control System must realize the monitoring and the operation that are distinguished "MLF beam" from "MR beam". And, we have developed the data distribution and acquisition system for "synchronized data" which required the distinguished monitoring and operation. We have designed and developed distribution and acquisition system using Reflective Memory (RM) for BPM data, which is one of synchronized data. There are 54 BPM, and BPM signal is processed by each BPM signal circuit (total 54 circuits). Then, we have designed that RM have 54 virtual ring memories and for a few seconds BPM data pre one virtual ring memory is buffered. And we decide BPM data is written virtual ring memory position based on "beam tag", which distributed from RM of J-PARC Timing System. This "beam tag" is synchronized across J-PARC. Thereby, 54 BPM data that written same virtual ring memory position become BPM data for identical beam. The paper presents the current status of the synchronized data distribution and acquisition system using RM.
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| THPP105 |
Beam Commissioning Results of the RCS Injection and Extraction at J-PARC
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3611 |
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- P. K. Saha, N. Hayashi, H. Hotchi, F. Noda, Y. Shobuda
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
- H. Harada
Hiroshima University, Graduate School of Science, Higashi-Hiroshima
- Y. Irie
KEK, Ibaraki
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The beam commissioning of J-PARC (Japan Proton Accelerator Research Complex) 3 GeV RCS (Rapid Cycling Synchrotron) has been started from the end of year 2007. As injection is in the very first stage, an accurate and well controlled beam at the injection strongly related to the other part of the RCS commissioning, including extraction where, an well extracted beam directly reflects the overall commissioning result. In this paper, the beam commissioning results of the RCS injection and extraction will be reported.
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