Author: Toyama, T.
Paper Title Page
TUCL2 A Development of High Sensitive Beam Profile Monitor using Multi-Screen 338
  • Y. Hashimoto, T. Toyama
    J-PARC, KEK & JAEA, Ibaraki-ken, Japan
  • T.M. Mitsuhashi, M. Tejima
    KEK, Ibaraki, Japan
  • S. Otsu
    Mitsubishi Electric System & Service Co., Ltd, Tsukuba, Japan
  The diagnostics of beam halo as well as beam core are very important for the regulation of the beam collimator. We have developed a monitor to observe two-dimensional beam profile with a large dynamic range. The monitor has been installed in 122m downstream from the beam collimator in 3-50 BT in the J-PARC. For measuring the beam core and the halo alternatively, the monitor has three kinds of screens. The first one is titanium foil OTR screen to measure a beam core, the second one is aluminum foil OTR screen having a hole (50 mm diameter) in the center, and the last one is a pair of alumina fluorescent screen with a separation of 80 mm in horizontal to observe the beam halo in surroundings. We designed an optical system based on the Offner optics for the observation of fluorescence and OTR lights. This optical system has an entrance aperture of 300 mm and it can cover the large opening angle (± 13.5 degree) of the OTR from 3GeV protons. A CID camera with an image intensifier (II) was use to observe the profile. We have succeeded to observe a profile of beam halo to 10-6 order to the peak of beam core by using proton beams of 9.6 x 1012 protons/pulse by this multi-screen scheme.  
slides icon Slides TUCL2 [3.091 MB]  
WEPC19 Performance of Injection Beam Position Monitors in the J-PARC RCS 716
  • N. Hayashi, P.K. Saha
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
  • T. Toyama
    J-PARC, KEK & JAEA, Ibaraki-ken, Japan
  It is important to monitor the injected beam trajectory and position into a synchrotron ring. In the J-PARC RCS, there are two specialized beam position monitors (BPM) in the first arc section in order to perform continuous monitoring. They detect the linac RF frequency 324 MHz or its second harmonics, these contributions quickly decrease after a few turns in the ring. Therefore, they are sensitive only just injected beam. The RCS adopts the multi-turn injection and transverse painting. These monitors are useful to check the beam behavior on-line.  
WEPF17 Development of a Beam Profile Monitor using a Nitrogen-Molecular Jet for the J-PARC MR 848
  • Y. Hashimoto, Y. Hori, T. Toyama
    J-PARC, KEK & JAEA, Ibaraki-ken, Japan
  • T. Fujisawa, T.M. Murakami, K. Noda
    NIRS, Chiba-shi, Japan
  • T. Morimoto, M. Uota
    KEK, Ibaraki, Japan
  • D. Ohsawa
    Kyoto University, Radioisotope Research Center, Kyoto-shi, Japan
  Funding: This work was supported by MEXT/JSPS KAKENHI Grant Number of 24310079 (Grant-in-Aid for Scientific Research(B)).
In order to measure a beam profile with a wide dynamic range covering the halo region around the core region of intense proton beams, a non-destructive beam profile monitor using a sheeted jet beam of nitrogen molecules as a target has been developed for the beam of the J-PARC main ring (MR)*,**. Two-dimensional detection of the beam core will be performed using de-excitation light of the nitrogen molecule. On the other hand, beam halo will be detected using ionized electrons. In the detection of the electrons, aμchannel plate (MCP) will be used for charge multiplication. To achieve a sensitivity of about 10-6, a phosphor screen will be employed for the anode of the MCP, and its light will be detected by photo-multiplier arrays for position resolving. Thus the beam core and halo will be detected simultaneously in this scheme. In this paper summaries of recent progress on the development are discussed as below: 1) the detection efficiency and accuracy in the measurement of the halo region, 2) simulation and experiment results of the high intensity jet beam of 5x10-4 Pa equivalent or more, 3) the specific design of the detector head in the collision point for J-PARC MR.
* Y. Hashimoto, et al., Proc. of IPAC’10, Kyoto, Japan, p.987-989.
** Y. Hashimoto, et al., Proc. of IBIC’12, Tsukuba, Japan.
poster icon Poster WEPF17 [0.672 MB]  
TUPC17 A Multiconductor Transmission Line Model for the BPMs at the 3-50 Beam Transport Line in J-PARC 403
  • T. Toyama, D.A. Arakara, M. Tejima
    KEK, Ibaraki, Japan
  • K. Hanamura
    Mitsubishi Electric System & Service Co., Ltd, Tsukuba, Japan
  • Y. Hashimoto, K. Satou
    J-PARC, KEK & JAEA, Ibaraki-ken, Japan
  We have developed an accurate and efficient analysis method with a multi-conductor transmission line model.  This method combines the two-dimensional electrostatic analysis including beams in the transverse plane and the transmission line analysis in the longitudinal direction.  The loads are also included in the boundary condition of the transmission line analysis.  Calculation of 2D electrostatic fields can be easily performed with the boundary element method. Taking low frequency limit of the formula, we have obtained an accurate expectation of the BPMs of 200 mm diameter at the 3-50 Beam Transport Line in J-PARC.