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Harada, H.

Paper Title Page
MOPEC068 High Intensity Beam Operations in the J-PARC 3-GeV RCS 624
 
  • H. Hotchi, H. Harada, P.K. Saha, Y. Shobuda, F. Tamura, K. Yamamoto, M. Yamamoto
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
  • Y. Irie
    KEK, Ibaraki
 
 

We have recently demonstrated 300-kW output in the J-PARC 3-GeV RCS. In this paper we will discuss beam dynamics issues in such a high intensity beam operation together with the corresponding beam simulation 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.

 
WEPEB065 Beam Loss of J-PARC Rapid Cycling Synchrotron at Several Hundred kW Operation 2842
 
  • K. Yamamoto, H. Harada, S. Hatakeyama, N. Hayashi, H. Hotchi, P.K. Saha, M. Yoshimoto
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
  • R. Saeki
    KEK/JAEA, Ibaraki-Ken
 
 

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.

 
THPEB016 Beam Fast Extraction Tuning of the J-PARC Main Ring 3918
 
  • G.H. Wei
    KEK/JAEA, Ibaraki-Ken
  • A. Ando, T. Koseki, J. Takano
    J-PARC, KEK & JAEA, Ibaraki-ken
  • K. Fan, S. Igarashi, K. Ishii, T. Nakadaira, M. Tomizawa, M. Uota
    KEK, Ibaraki
  • H. Harada, P.K. Saha
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
 
 

The beam commissioning of J-PARC/MR has been started from May 2008 and is in progress*. One key purpose of MR commissioning is the 30 GeV beam fast extraction to Neutrino beam line, which reflect the overall commissioning result. In the MR, the third straight section is assigned for the fast extraction. 5 kickers and 8 septa were installed there, which can give beam a bipolar kick to inside or outside of MR. Inside kick means beam to Neutrino Oscillation Experiment, while outside kick means beam dumped to abort line. However before commissioning, the measured magnetic field distribution of each septa shows non-linear profile along the horizontal direction. In order to find the influence, a simulation with these measured field has been performed. Depends on this study and some OPI (Operation Interface) made by code SAD for orbit modification online, fast extraction of 30 GeV beam to Neutrino line has been achieved on April 23rd 2009. Beam orbit have been tuned to less than 0.5 mm and 0.1 mrad in both horizontal and vertical at the beginning of Neutrino line, which is also the end of MR fast extraction. And so far, 100 kW continual operation to neutrino line have been achieved, too.


* T. Koseki, "Challenges and Solutions for J-PARC Commissioning and Early Operation", in these proceedings

 
THPEB018 Systematic Beam Loss Study due to the Foil Scattering at the 3-GeV RCS of J-PARC 3921
 
  • P.K. Saha, H. Harada, H. Hotchi, K. Yamamoto, Y. Yamazaki, M. Yoshimoto
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
  • I. Sugai
    KEK, Ibaraki
 
 

The beam loss caused by the nuclear scattering together with the multiple Coulomb scattering at the stripping foil is one of the key issue in RCS (Rapid Cycling Synchrotron) of the J-PARC (Japan Proton Accelerator Research Accelerator). In order to have a very realistic understanding, a systematic study with both experiment and simulation has been carried out recently. A total of seven targets with different thickness were used and the measured beam losses were found to be good in agreement with that in the simulation. A detail and realistic understanding from such a study will be very useful not only to optimize the foil system including the thickness and size at present with the injection beam energy of 181 MeV but also for the near future upgrade with 400 MeV and in addition can be a good example for similar existing and proposing projects.

 
THPEB020 Beam Study Results with HBC Stripping Foils at the 3-GeV RCS in J-PARC 3927
 
  • M. Yoshimoto, H. Harada, N. Hayashi, H. Hotchi, Y. Irie, M. Kawase, M. Kinsho, R. Saeki, P.K. Saha, K. Yamamoto, Y. Yamazaki
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
  • T. Ishiyama
    KEK/JAEA, Ibaraki-Ken
  • I. Sugai
    KEK, Ibaraki
 
 

The hybrid type thick boron-doped carbon (HBC) stripping foils are installed and used for the beam injection at the 3GeV RCS (Rapid Cycling Synchrotron) in J-PARC (Japan Proton Accelerator Research Complex). The HBC foils are developed by Sugai group in KEK, which improved the lifetime drastically. Up to now, the performance deterioration of the stripping foils can not be seen after the long beam irradiation for the 120kW user operation and 300kW high power beam demonstration at the RCS. In order to examine the characteristic of the HBC foils, various beam studies were carried out. The beam-irradiated spot at the foil was measured by scanning the foil setting position, the charge exchange efficiency was evaluated with various thickness foils, and the effect of the SiC fibers supporting the foil mounting was checked with different mounting foils. Beam study results obtained with using the HBC foils will be presented. In addition, the trends of outgas from the stripping foils and the deformations of the foils during the beam irradiation will be reported.