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Harada, Hiroyuki; Meigo, Shinichiro; Shirakata, Masashi*; Sato, Yoichi*; Tamura, Fumihiko; Tejima, Masaki*; Hashimoto, Yoshinori*; Igarashi, Susumu*; Koseki, Tadashi
JPS Conference Proceedings (Internet), 8, p.012010_1 - 012010_6, 2015/09
The J-PARC 3-50BT line is the beam transport line from 3-GeV rapid-cycling synchrotron (RCS) to 50-GeV main ring (MR). The RCS is the high-intensity proton accelerator, where designed beam power is 1 MW, and has the complex source of space charge effect, etc. Therefore, the uncontrolled emittance growth and beam halo increase nonlinearly with the increasing the beam power. Additionally, the physical aperture of MR with 81 
mm mrad is smaller than that of RCS with 486 mm mrad. Therefore, the 3-50BT line has the collimators in order to remove the tail or halo of the extracted beam from the RCS. The designed collimator aperture is 54 mm mrad. It is required to measure and optimize the optics parameters in the collimator area for taking full advantage of the beam collimation. Especially, it is very important to make the dispersion functions free in the collimator area and optimize the beta function. This paper will introduce the method of optics measurement and report the result of the measurement and optimization based on the simulation.
Harada, Hiroyuki; Meigo, Shinichiro; Shirakata, Masashi*; Sato, Yoichi*; Tamura, Fumihiko; Tejima, Masaki*; Hashimoto, Yoshinori*; Igarashi, Susumu*; Koseki, Tadashi
Proceedings of 10th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.39 - 43, 2014/06
The J-PARC 3-50 BT line is the beam transport line of extracted beam from 3-GeV rapid-cycling synchrotron (RCS) to 50-GeV main ring (MR). The RCS is the high-intensity proton accelerator, which designed beam power is 1 MW, and has the complex source of space charge effect, etc. Therefore, the uncontrolled emittance growth and beam halo increase nonlinearly with the increasing the beam power. Additionally, physical aperture of MR with 81 mm mrad is smaller than that of RCS with 486 mm mrad. Therefore, the 3-50 BT line has the collimators in order to scrape the tail/halo of extracted beam from the RCS. The designed collimator aperture is 54 mm mrad. It is required to measure and optimize the optics parameter in the collimator area for taking full advantage of beam collimation. This paper will introduce the method of optics measurement and report the result of the measurement and optimization based on the simulation.
Hayashi, Naoki; Kawase, Masato; Hatakeyama, Shuichiro; Hiroki, Seiji; Saeki, Riuji; Takahashi, Hiroki; Teruyama, Yuzo*; Toyokawa, Ryoji*; Arakawa, Dai*; Hiramatsu, Shigenori*; et al.
Nuclear Instruments and Methods in Physics Research A, 677, p.94 - 106, 2012/06
Times Cited Count：12 Percentile：66.54(Instruments & Instrumentation)A beam position monitor (BPM) system at J-PARC RCS is described. The J-PARC RCS is a rapid-cycling proton synchrotron and its designed beam power is 1 MW. A diameter of the BPM detector is larger than 250 mm, however the system has to measure the beam position very accurately. The system should work not only for the high intensity but also for lower intensity. There are 54 BPM around the ring and most of them are placed inside steering magnets because of quite limited space. The BPM detector is an electro static type and it has four electrodes, and a pair of electrode gives a good linear response with diagonal cut shape to detect the charge center precisely. The signal processing unit, which is equipped with 14-bit 40 MSPS ADC and 600 MHz DSP, has been developed. They are controlled via shared memory space and EPICS. It is capable to record full 25 Hz pulse data for averaged mode and it could also store whole waveform data for further analysis, like turn-by-turn position calculation.
Hayashi, Naoki; Hatakeyama, Shuichiro; Harada, Hiroyuki; Hotchi, Hideaki; Takano, Jumpei*; Tejima, Masaki*; Toyama, Takeshi*
Proceedings of 46th ICFA Advanced Beam Dynamics Workshop on High-Intensity and High-Brightness Hadron Beams (HB 2010) (Internet), p.57 - 61, 2010/09
The Beam Based Alignment (BBA) of the BPM is inevitable for precise and absolute beam position measurements. Even though careful fabrication and installation of the BPM detector, it has to be calibrated by using the beam. Usually, it requires that the individual quadrupole magnet is able to be controlled. However, it is not always that case. In addition, scanning over the all BPM is time consuming procedure. The BBA method under coupled QM environment would help to reduce time for calibration. It presents general formula and experiences at J-PARC RCS and parts of results are compared with the ordinal method at J-PARC MR.
Hatakeyama, Shuichiro; Toyama, Takeshi*; Tejima, Masaki*
Proceedings of 7th Annual Meeting of Particle Accelerator Society of Japan (DVD-ROM), p.631 - 633, 2010/08
The beam commissioning of J-PARC MR (Main Ring) started in 2008. The current beam power of the user operation is 40 kW - 70 kW which corresponds 1/10 of the designed value of 1st stage. One of the hurdle to clear for the power up is the beam loss at the injection. A candidate of the origin of the injection beam loss is the error of bending angles of RCS extraction magnets and MR injection magnets, therefore it is required to monitor continuously the transverse injection error. The transverse injection error can be calculated using beam bunch positions at the injection. For this purpose a dedicated digitizer is used to acquire the waveform of BPM. It is also monitored the betatron tune using the same digitizer. Processing the injected 93 turns beam bunch positions by FFT it is realized the continuous monitoring with 3.52 s operating cycle. When determining the beam bunch position, the digital-high-pass filtering is adapted to the waveform of BPM to remove the slow component of noise.
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.
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.
Tejima, Masaki*; Arakawa, Dai*; Hashimoto, Yoshinori*; Sato, Kenichiro*; Toyama, Takeshi*; Yamamoto, Noboru*; Hayashi, Naoki; Hanamura, Kotoku*
Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.978 - 980, 2010/05
To maintain the beam orbit of beam transport line from RCS to MR in J-PARC (3-50BT), 14 beam position monitors (BPMs) were installed. Their signals gathered in the local control building (D01) have been measured by using 14 digitizing oscilloscopes. The data acquisition system have a performance of shot-by-shot measurement.
Toyama, Takeshi*; Arakawa, Dai*; Hiramatsu, Shigenori*; Igarashi, Susumu*; Lee, S.*; Matsumoto, Hiroshi*; Odagiri, Junichi*; Tejima, Masaki*; Tobiyama, Makoto*; Hashimoto, Yoshinori*; et al.
Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.981 - 983, 2010/05
Experiences of operating BPM's during beam commissioning at the J-PARC MR are reported. The subjects are: (1) bug report, statistics and especially the effect of a beam duct step, (2) position resolution estimation (
30 micrometers with 1 sec averaging), (3) beam based alignment.
Hayashi, Naoki; Hiroki, Seiji; Saeki, Riuji; Toyokawa, Ryoji; Yamamoto, Kazami; Yoshimoto, Masahiro; Arakawa, Dai*; Hiramatsu, Shigenori*; Lee, S.*; Sato, Kenichiro*; et al.
Proceedings of 11th European Particle Accelerator Conference (EPAC '08) (CD-ROM), p.1125 - 1127, 2008/06
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. 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 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. Dedicated BPMs, Fast CT (FCT) and Wall Current Monitor (WCM) are used for RF feedback or feedfoward control. It will describe the performance of each instruments and how they are contributed to the successful beam commissioning.
Hayashi, Naoki; Hiroki, Seiji; Saeki, Riuji; Toyokawa, Ryoji*; Yamamoto, Kazami; Arakawa, Dai*; Hiramatsu, Shigenori*; Lee, S.*; Sato, Kenichiro*; Tejima, Masaki*; et al.
Proceedings of 11th European Particle Accelerator Conference (EPAC '08) (CD-ROM), p.1128 - 1130, 2008/06
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.
Hayashi, Naoki; Hiroki, Seiji; Saha, P. K.; Saeki, Riuji; Toyokawa, Ryoji*; Yamamoto, Kazami; Yoshimoto, Masahiro; Arakawa, Dai*; Hiramatsu, Shigenori*; Lee, S.*; et al.
Proceedings of 5th Annual Meeting of Particle Accelerator Society of Japan and 33rd Linear Accelerator Meeting in Japan (CD-ROM), p.243 - 245, 2008/00
The J-PARC RCS has been beam commissioned since fall 2007. During such a short period, the following items have been established. Establishment of the injection orbit, beam circulation, acceleration up to 3GeV, optics parameters measurements and it achieved 50 kW beam power (4
10
ppb). The beam monitor system has an important role for smooth beam commissioning. This paper describes the status of the beam monitor system, BPM, Injection monitors, IPM, current monitor, tune meter and BLM of the RCS.
