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Toyama, T.

Paper Title Page
MOPE011 Shot-by-shot Beam Position Monitor System for Beam Transport Line from RCS to MR in J-PARC 978
 
  • M. Tejima, D.A. Arakawa, Y. Hashimoto
    KEK, Ibaraki
  • K. Hanamura
    MELCO SC, Tsukuba
  • N. Hayashi
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
  • K. Satou, T. Toyama, N. Yamamoto
    J-PARC, KEK & JAEA, Ibaraki-ken
 
 

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.

 
MOPE014 Development of a Nondestructive Beam Profile Monitor using a Sheeted Nitrogen-molecular Beam 987
 
  • Y. Hashimoto, T. Toyama
    J-PARC, KEK & JAEA, Ibaraki-ken
  • T. Fujisawa
    AEC, Chiba
  • T. Morimoto
    Morimoto Engineering, Iruma, Saitama
  • T.M. Murakami, K. Noda
    NIRS, Chiba-shi
  • S. Muto
    KEK, Ibaraki
  • D. Ohsawa
    Kyoto University, Radioisotope Research Center, Kyoto-shi
 
 

A nondestructive beam profile monitor using a nitrogen-molecule gas-jet sheet has been developed for intense ion beams. The density of the gas-jet sheet corresponds to 1 x 10-3 Pa. A light emitted from nitrogen excited by an ion beam collision is measured with a high sensitive camera attached a radiation hard image intensifier. In tests, beam profiles of 6 MeV/u full-stripped oxygen beams whose peak current was 600 μA. were measured. This paper describes characteristics of the instruments and the beam test results.

 
MOPE015 Application of a Single-Wire Proportional Counter to the Beam Loss Monitoring at J-PARC MR 990
 
  • K. Satou, T. Toyama
    J-PARC, KEK & JAEA, Ibaraki-ken
  • H. Harada, K. Yamamoto
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
 
 

A single-wire proportional counter which has the maximum gain of 6·104 is used as a beam loss monitor (p-BLM), thus low-level beam loss can be monitored. However, it involves gain reduction problem by the space charge effect. It is essential to estimate the space charge effect to utilize a proportional counter for beam loss monitoring. The calibration procedure is discussed for the p-BLMs for 3-50BT and MR. Measurements of residual dose were made and some nuclei were identified. Radiation from the short-life nucleus, Fe53 (T1/2=8.51m), may be a good index to predict a residual dose after a long term beam operation.

 
MOPE020 Beam Based Alignment of the Beam Position Monitor at J-PARC RCS 1005
 
  • N. Hayashi, H. Harada, H. Hotchi
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
  • M. Tejima
    KEK, Ibaraki
  • T. Toyama
    J-PARC, KEK & JAEA, Ibaraki-ken
 
 

The J-PARC RCS is an M-Watt class rapid cycling synchrotron and it has delivered an intensive beam to the neutron target and the MR. In order to overcome large space charge effect, its physical aperture is designed to be more than 250mm in diameter. Even though its chamber size is very large, the BPM system gives precise data to determine beam optics parameters of the ring. For this purpose, only 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 and measured the position with respect to the quadrupole magnet (QM) nearby. 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.

 
TUPD044 Horizontal Impedance of the Kicker Magnet of RCS at J-PARC 2024
 
  • Y. Shobuda, J. Kamiya, M. Watanabe
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
  • T. Toyama
    J-PARC, KEK & JAEA, Ibaraki-ken
 
 

There is the famous formula of the horizontal impedance for the matched-traveling wave kicker. However, the real and the imaginary parts of the impedance do not satisfy the Hilbert transformations. On the other hand, the impedance measured by a loop method does not directly give the beam impedance. In this paper we theoretically derive the beam impedance and reproduce the impedance by using the estimated inductances of the kicker by the loop measurement.

 
WEPEB005 Magnet Pattern Control System of the J-PARC Main Ring 2692
 
  • J. Takano, T. Koseki, S. Nakamura, T. Toyama, N. Yamamoto
    J-PARC, KEK & JAEA, Ibaraki-ken
  • S. Hatakeyama
    JAEA/J-PARC, Tokai-mura
  • K. Niki, M. Tomizawa, S. Yamada
    KEK, Ibaraki
 
 

In the J-PARC Main Ring (MR), the bending, quadrupole, sextupole, and steering magnets can be controlled on the operating interfaces (OPI). The optics parameters for all magnets are calculated by using SAD, and are converted to BL tables (ex: 2000 points for a steering magnet) for each power supplies. The BL tables are made from the parameters of optics, pattern timing, and beam energy at flat bottom and flat top. For MR beam studies, the BL tables are adjustable with offset and factor. This system is useful for COD correction, beta function measurement, aperture survey, and slow extraction. In this proceeding, the structure of the magnet control system and OPIs for beam studies will be shown.

 
TUPEA051 Application of Digital Narrow Band Noise to J-PARC Main Ring 1446
 
  • A. Schnase, K. Hasegawa, M. Nomura, T. Shimada, H. Suzuki, F. Tamura, M. Yamamoto
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
  • K. Hara, C. Ohmori, M. Tada, M. Yoshii
    KEK/JAEA, Ibaraki-Ken
  • T. Koseki, T. Toyama
    J-PARC, KEK & JAEA, Ibaraki-ken
  • M. Tomizawa
    KEK, Ibaraki
 
 

Applying narrow band longitudinal noise to the beam in J-PARC Main Ring in flattop, while the acceleration voltage is off might help to counteract the effect of ripple on the slow extraction. For this purpose, a complex noise sequence output by DSP modulates a custom made DDS synthesizer to create single side spectra without carrier. The noise is calculated starting from a description in frequency domain. Then an algorithm creates narrow band spectra with optimized behavior in time domain. Frequency domain data is transformed to time domain, and the amplitude is smoothed. The smoothed data is transformed back to frequency domain, and the spectral shape is restored. This process repeats until the amplitude in time domain has converged, while the desired spectrum shape is preserved. Noise generated in this way can be tailored for different requirements. We show the signal properties, the hardware, and preliminary beam test results, when the noise is applied to the MR RF system.

 
MOPE012 Performance of the Main Ring BPM during the Beam Commissioning at J-PARC 981
 
  • T. Toyama, D.A. Arakawa, S. Hiramatsu, S. Igarashi, S. Lee, H. Matsumoto, J.-I. Odagiri, M. Okada, M. Tejima, M. Tobiyama
    KEK, Ibaraki
  • K. Hanamura, S. Hatakeyama
    MELCO SC, Tsukuba
  • Y. Hashimoto, K. Satou, J. Takano
    J-PARC, KEK & JAEA, Ibaraki-ken
  • N. Hayashi
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
 
 

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.

 
WEPEB036 Bunch by Bunch Feedback Systems for J-PARC MR 2767
 
  • M. Tobiyama, Y.H. Chin, Y. Kurimoto, T. Obina, M. Tejima, T. Toyama
    KEK, Ibaraki
  • Y. Shobuda
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
 
 

Transverse bunch by bunch feedback systems for J-PARC MR accelerator has been designed and tested. Bunch positions are detected by Log-ratio position detection systems with center frequency of 12 MHz. The digital filter which consists of two LLRF4 boards samples the position signal with 64 times of RF frequency. Up to four sets of 16 tap FIR filter with one-turn delay and digital shift gain can be used. Preliminary results of beam test of the system are also shown.

 
WEPEB007 The Data Acquisition System of Beam Position Monitors in J-PARC Main Ring 2698
 
  • S. Hatakeyama, N. Hayashi
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
  • D.A. Arakawa, Y. Hashimoto, S. Hiramatsu, J.-I. Odagiri, M. Tejima, M. Tobiyama, T. Toyama, N. Yamamoto
    KEK, Ibaraki
  • K. Hanamura
    MELCO SC, Tsukuba
  • K. Satou
    J-PARC, KEK & JAEA, Ibaraki-ken
 
 

The Data Acquisition System of Beam Position Monitors(BPMs) in J-PARC Main Ring are consist of 186 Linux-based Data Processing Cirquits(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.

 
THPEA081 Vacuum Surface Scrubbing by Proton Beam in J-PARC Main Ring 3858
 
  • M. Uota, Y. Hashimoto, Y. Hori, H. Matsumoto, Y. Saitoh, M. Shimamoto, M. Tomizawa, T. Toyama
    KEK, Ibaraki
 
 

In J-PARC 50GeV synchrotron ring, large vacuum pressure rises above 10-3 Pa are found at 30GeV acceleration final stage of intensity over 1013 protons per pulse in the chambers of the in-vacuum electrostatic septum magnet for the slow-extraction(SX), magnetic septum for SX, and the kicker magnet for the fast-extraction. This pressure rise depends on beam intensity and peak-current, and can be reduced by continuous beam operations, such as scrubbing with proton beam, secondary emission electrons and other cations of remaining gasses or desorptions.

 
THPEB014 Status and Upgrade Plan of Slow Extraction from the J-PARC Main Ring 3912
 
  • M. Tomizawa, T. Adachi, Y. Arakaki, A. Kiyomichi, S. Murasugi, R. Muto, H. Nakagawa, K. Niki, K. Okamura, Y. Sato, S. Sawada, Y. Shirakabe, H. Someya, K.H. Tanaka, T. Toyama, E. Yanaoka
    KEK, Ibaraki
  • A. Ando, Y. Hashimoto, T. Koseki, J. Takano
    J-PARC, KEK & JAEA, Ibaraki-ken
  • D. Horikawa, I. Sakai
    University of Fukui, Faculty of Engineering, Fukui
  • K. Mochiki, S. Onuma
    Tokyo City University, Tokyo
  • H. Sato
    Tsukuba University, Ibaraki
  • A. Schnase
    JAEA/J-PARC, Tokai-mura
 
 

High power protons from the J-PARC main ring is slowly extracted using the third integer resonance and delivered to the experimental hall for various nuclear and particle physics experiments. The slow extraction device comprises two electro static septa (ESS),ten magnetic septa, four bump magnets, eight resonant sextupole magnets and their power supply. One of the critical issue of the slow extraction is radiation caused by the beam loss during the slow extraction. We have developed the electrostatic and magnetic septa with thin septum thickness. A unique scheme with large step size and small angular spread of the extracted beam enables hit rate on the ESS less than 1% level. In January 2009, first 30 GeV proton beam has been successfully delivered to the fixed target. Quadrupole magnets and a DSP feedback control system to obtain a uniform beam spill structure were implemented in 2009 summer shutdown period. We will report the extraction efficiency, extracted beam profiles and spill structure obtained by the beam commissioning so far. We will also mention a upgrade plan based on some new ideas to aim a higher performance.