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Journal Articles

Development of a beam window protection system for the J-PARC Linac

Takahashi, Hiroki; Hatakeyama, Shuichiro; Sawabe, Yuki; Miyao, Tomoaki*; Ishiyama, Tatsuya*; Suzuki, Takahiro*

Journal of Physics; Conference Series, 1350, p.012142_1 - 012142_5, 2019/12

 Times Cited Count:0 Percentile:100

At the J-PARC Linac, beam conditioning and study are performed using beam dumps (BDs). To be a partition with the high vacuum section, a beam window (material Ni, 0.38 mm thick, mirror-shape) is installed upstream of the BD along the beam line. Beams that can be accepted by the beam window are about 1/50 or less of rated beam according to thermal evaluation and experience. Therefore, when using a beam dump, it is necessary not to exceed this tolerance. In a 2018 beam study, the beam e that exceeded tolerance was incident on the 0-degree dump due to human error, and the beam window was cracked. Then, this has revealed the need for protection of the beam window by hardware. Therefore, based on the existing system for monitoring the per-hour beam amount, we began to develop a system to monitor one shot beam and one second beam amount. And, we succeeded in implementing a system that protects the beam window by monitoring the beam in a short time (one shot, and for one second). In addition, the performance tests using actual beams were performed, and it was confirmed that the developed system had sufficient performance requirements to protect the beam window.

Journal Articles

Beam monitor data analysis of interlocked events at J-PARC RCS

Hayashi, Naoki; Yoshimoto, Masahiro; Moriya, Katsuhiro; Hatakeyama, Shuichiro*

Proceedings of 16th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1096 - 1100, 2019/07

It is necessary to understand the reason why the accelerator has been interrupted due to beam loss or other machine mal function in order to keep high availability in long term period. At J-PARC RCS, 25 Hz rapid-cycling synchrotron, there is a system to record beam intensity and beam loss monitor signal for all pulses with 10 ms period. At this time, in addition, new system to archive data with better time resolution if interlocked events occurred has been introduced. Using these archived data, the events only RCS BLM gives MPS have been analyzed and it turns out that these events are related to the ion source discharge which makes very low intensity within less than a second. In this paper other typical events are presented and discuss how to improve the accelerator performance in future.

Journal Articles

Development of a beam window protection system for the J-PARC Linac

Takahashi, Hiroki; Hatakeyama, Shuichiro; Sawabe, Yuki; Miyao, Tomoaki*; Ishiyama, Tatsuya*; Suzuki, Takahiro*

Proceedings of 10th International Particle Accelerator Conference (IPAC '19) (Internet), p.3886 - 3889, 2019/06

At the J-PARC Linac, beam conditioning and study are performed using beam dumps (BDs). To be a partition with the high vacuum section, a beam window (material Ni, 0.38 mm thick, mirror-shape) is installed upstream of the BD along the beam line. Beams that can be accepted by the beam window are about 1/50 or less of rated beam according to thermal evaluation and experience. Therefore, when using a beam dump, it is necessary not to exceed this tolerance. In a 2018 beam study, the beam e that exceeded tolerance was incident on the 0-degree dump due to human error, and the beam window was cracked. Then, this has revealed the need for protection of the beam window by hardware. Therefore, based on the existing system for monitoring the per-hour beam amount, we began to develop a system to monitor one shot beam and one second beam amount. And, we succeeded in implementing a system that protects the beam window by monitoring the beam in a short time (one shot, and for one second). In addition, the performance tests using actual beams were performed, and it was confirmed that the developed system had sufficient performance requirements to protect the beam window.

Journal Articles

Analysis of interlocked events based on beam instrumentation data at J-PARC Linac and RCS

Hayashi, Naoki; Hatakeyama, Shuichiro; Miura, Akihiko; Yoshimoto, Masahiro; Futatsukawa, Kenta*; Miyao, Tomoaki*

Proceedings of 7th International Beam Instrumentation Conference (IBIC 2018) (Internet), p.219 - 223, 2019/01

J-PARC is a multi-purpose facility. Accelerator stability is the one of important issues for users of this facility. To realize stable operation, we must collect data on interlocked events and analyze these data to determine the reasons for the occurrence of such events. In J-PARC Linac, data of interlocked events have been recorded using several some beam loss monitors and current monitors, and these data have been are analyzed and classified. In J-PARC RCS, new instrumentation is being introduced to obtain beam position. We discuss the present status and future plans related to this subject.

Journal Articles

Monitoring of the injected beam to the J-PARC RCS and BPM design for H0 dump line

Hayashi, Naoki; Saha, P. K.; Yoshimoto, Masahiro; Hatakeyama, Shuichiro

Proceedings of 15th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1055 - 1059, 2018/08

The J-PARC Rapid-Cycling Synchrotron (RCS) is designed as an 1-MW high power accelerator. It has been operated since 2007, and its injection energy and beam current are upgraded in 2014. Its operation is very smooth and provides the high intensity beam to the Material and Life science experimental facility (MLF) and the Main Ring (MR). The beam is injected with multi-turn mode. It is possible because the negative hydrogen ion beam from the Linac, H$$^{-}$$, and the circulating proton beam H$$^{+}$$ are different state. The H$$^{-}$$ is converted to H$$^{+}$$ at the injection point, where a charge stripper foil is set. A small fraction of the injected beam, which is not fully stripped, are transferred to the injection beam dump through H0 dump line to prevent un-necessary activation. Since the limit of beam dump is only 4 kW, which is about 3% of designed injection beam power 133 kW, the beam has to be stopped immediately in case of stripper foil break up incident.

Journal Articles

Beam instrumentation at the 1 MW Proton beam of J-PARC RCS

Yamamoto, Kazami; Hayashi, Naoki; Okabe, Kota; Harada, Hiroyuki; Saha, P. K.; Yoshimoto, Masahiro; Hatakeyama, Shuichiro; Hotchi, Hideaki; Hashimoto, Yoshinori*; Toyama, Takeshi*

Proceedings of 54th ICFA Advanced Beam Dynamics Workshop on High-Intensity, High Brightness and High Power Hadron Beams (HB 2014) (Internet), p.278 - 282, 2015/03

Rapid Cycling Synchrotron (RCS) of Japan Proton Accelerator Complex (J-PARC) is providing more than 300 kW of proton beam to Material and Life science Facility (MLF) and Main Ring (MR). Last summer shutdown, a new ion source was installed to increase output power to 1 MW. In order to achieve reliable operation of 1 MW, we need to reduce beam loss as well. Beam quality of such higher output power is also important for users. Therefore we developed new monitors that can measure the halo with higher accuracy. We present beam monitor systems for these purposes.

Journal Articles

MWPM DAQ System for J-PARC RCS

Hatakeyama, Shuichiro; Yoshimoto, Masahiro

Proceedings of 11th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.703 - 705, 2014/10

The J-PARC LINAC introduced ACS (Annular-ring Coupled Structure) cavity and now available the 400 MeV beam extraction. As for the RCS (Rapid Cycling Synchrotron) the power supply of the injection magnets were replaced those can acceptable the 400 MeV beam injection. Because there occured many troubles of equipments in the early phase of the beam study, we desired to shorten the measurement time of the beam monitor to determine the parameters. In this report it is described the signal processing system of MWPM (Multi-wire profile monitor) which is used to measure the injection beam profile for better accuracy and shorter measurement time.

Journal Articles

Pulse based data archive system and analysis for current and beam loss monitors in the J-PARC RCS

Hayashi, Naoki; Hatakeyama, Shuichiro; Yamamoto, Kazami

Proceedings of 5th International Particle Accelerator Conference (IPAC '14) (Internet), p.3800 - 3802, 2014/07

The data archive system in the J-PARC 25-Hz Rapid-Cycling Synchrotron (RCS) records the beam intensity and the beam loss monitor (BLM) pattern for all pulses. The system is based on the common memory and utilizes the timing system of the J-PARC. Although its time resolution is limited, it is useful to detect rare events or phenomena appearing with only higher accelerator repetition. Using these data, the stability of the beam intensity, particularly ion source or the relation between BLM patterns and its causes can be studied pulse-by-pulse basis and it would make use of future improvements.

Journal Articles

Development of data aqcuisition system of J-PARC RCS multi-wire profile monitor using multi-channel digitizer

Hatakeyama, Shuichiro; Yoshimoto, Masahiro

Proceedings of 10th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1082 - 1084, 2014/06

In J-PARC RCS (Rapid Cycling Synchrotron), in order to perform transverse orbit matching of the injection beam, it is used a total of 7 sets of multi-wire profile monitors (MWPMs). It is considered that beam loss around the equipments of injection beam line will be increased significantly because it is planed the beam power from the LINAC will be enforced in this fiscal year. So we will install a new MWPM on the H0 dump line to measure the injection orbit more precicely. In this time, we have developed a new data acquisition system using multi-channel digitizer. As the feature, it is improved the S/N ratio as compared with the present system using a multiplexer. Also the cost of the new system is estimated to be lower than the present system. In this report it is described the performance of the new DAQ system by using real beam with the existing MWPM2.

Journal Articles

Beam loss monitor system of the Rapid Cycling Synchrotron of Japan Proton Accelerator Research Complex

Yamamoto, Kazami; Hayashi, Naoki; Hatakeyama, Shuichiro; Saeki, Riuji; Iwama, Yuhei

Proceedings of 10th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1060 - 1064, 2014/06

The 3 GeV Rapid Cycling Synchrotron (RCS) of the Japan Proton AcceleratoR Complex (J-PARC) provides more than 300 kW beam to the Material and Life Science Facility (MLF) and the Main Ring (MR). In such high intensity hadron accelerator, the lost protons that are a fraction of the beam less than 0.1% cause many problems. Those particles bring about a serious radioactivation and a malfunction of the accelerator components. Therefore, the beam loss monitor (BLM) is one of the most important equipment to observe the state of the beam during operation, and to keep a steady operation. Moreover, if we set operation parameters of BLM adequately, it can detect the beam loss that is 10$$^{-6}$$ fraction of the beam. Thus it enables fine-tuning of the accelerator. In the J-PARC RCS, a proportional counter and a plastic scintillation counter are used for the beam commission and the stable operation as BLM. We report present status of the BLM system in J-PARC RCS.

JAEA Reports

Research for spectroscopy of fuel debris using superconducting phase transition edge sensor microcalorimeter; Measurement experiment and simulated calculation (Joint research)

Takasaki, Koji; Yasumune, Takashi; Onishi, Takashi; Nakamura, Keisuke; Ishimi, Akihiro; Ito, Chikara; Osaka, Masahiko; Ono, Masashi*; Hatakeyama, Shuichi*; Takahashi, Hiroyuki*; et al.

JAEA-Research 2013-043, 33 Pages, 2014/01

JAEA-Research-2013-043.pdf:13.81MB

In the Fukushima Daiichi Nuclear Power Plant, it is assumed that the core fuels melted partially or wholly, and the normal technique of accounting for a fuel assembly is not applicable. Therefore, it is necessary to develop the transparent and rational technique of accounting in the process of collection and storage of fuel debris. In this research, an application of the superconducting phase Transition Edge Sensor microcalorimeter (TES microcalorimeter) is studied for the accounting of nuclear materials in the fuel debris. It is expected that the detailed information of nuclear materials and fission products in fuel debris is obtained by using a high-resolution characteristic of TES microcalorimeter. In this report, the principle of TES microcalorimeter, the measurement experiment using TES in JAEA, and the simulated calculation using the EGS5 code system are summarized.

Journal Articles

Advanced uses of a current transformer and a mult-wire profile monitor for online monitoring of the stripper foil degradation in the 3-GeV RCS of J-PARC

Saha, P. K.; Harada, Hiroyuki; Hatakeyama, Shuichiro; Hayashi, Naoki; Hotchi, Hideaki; Kinsho, Michikazu; Okabe, Kota; Saeki, Riuji; Yamamoto, Kazami; Yamazaki, Yoshio; et al.

Proceedings of 2nd International Beam Instrumentation Conference (IBIC 2013) (Internet), p.239 - 242, 2013/12

Journal Articles

Beam position monitor system of J-PARC RCS

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:7 Percentile:43.25(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.

Journal Articles

Various methods to measure the betatron tune of the synchrotron

Hatakeyama, Shuichiro

Proceedings of 3rd International Particle Accelerator Conference (IPAC '12) (Internet), p.843 - 845, 2012/05

Generally in the synchrotron, the frequency of transverse oscillation of the bunched beam for each single turn (usually called betatron tune or just "tune") is one of fundamental controllable knobs to avoid the instability of the accelerator. In this report, it is not mentioned about the effect to the beam instability but it is focused to various methods to measure the betatron tune by using bunch-by-bunch transverse beam position. The following items will be presented, (1) least square fitting to the time-domain beam position at specific location. (2) peak finding of the frequency-domain beam position at specific location. (3) phase space analysis of the beam position at specific location. (4) frequency-domain analysis of the beam position in the normalized coordinate at many locations in the ring orbit. For the application to the real accelerator, data of the J-PARC (Japan Proton Accelerator Research Complex) will be shown.

Journal Articles

Comparison of the residual doses before and after resumption of user operation in J-PARC RCS

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

Proceedings of 3rd International Particle Accelerator Conference (IPAC '12) (Internet), p.3901 - 3903, 2012/05

J-PARC Facilities were seriously damaged by the Great East Japan Earthquake in March 2011, but all facilities resumed a beam operation from December 2012. Beam commissioning results indicated that the beam loss and the residual dose at injection area in the RCS was reduced to 10% of before earthquake. This result owed to new collimator at injection area. The losses and residual doses of other area were almost same as before earthquake.

Journal Articles

Beam based alignment of synchrotron under coupled quadrupole magnet environment

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.

Journal Articles

Online monitoring of the H0 dump beam current during user operation of J-PARC RCS

Hatakeyama, Shuichiro; Saha, P. K.; Yoshimoto, Masahiro; Yamamoto, Kazami; Hayashi, Naoki; Sato, Kenichiro*

Proceedings of 7th Annual Meeting of Particle Accelerator Society of Japan (DVD-ROM), p.1013 - 1015, 2010/08

In J-PARC (Japan Proton Accelerator Research Complex), the negative hydrogen ions (H$$^{-}$$) accelerated by LINAC are converted to protons (H$$^{+}$$) by the Charge Stripping Foil before injecting into RCS (Rapid Cycling Synchrotron). About 99.7% of H$$^{-}$$ are stripped it's two electrons by the 1st foil. The rest of H0 and H$$^{-}$$ are converted to H$$^{+}$$ by 2nd and 3rd foils and abandoned into H0 dump. Monitoring of the fraction of beam current into the H0 dump gives useful information for the stable beam supply during accelerator user's operation. This report describes the method of online monitoring to estimate the beam current of the H0 dump line.

Journal Articles

A System for monitoring of the transverse injection error and betatron tune in 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.

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

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.

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