03 Technology
3G Beam Diagnostics
Paper Title Page
TUPLB09 Design and Beam Test of Six-electrode BPMs for Second-order Moment Measurement 464
 
  • K. Yanagida, H. Hanaki, S. Suzuki
    JASRI/SPring-8, Hyogo-ken, Japan
 
  In the SPring-8 linac, four-electrode beam position monitors (BPMs) have been utilized for the measurement of the transverse first-order moments, which correspond to the centroids of beam charge distributions. We have planed to measure the transverse second-order moments of beams to obtain information of beam optics and its energy deviations during the top-up beam injection without destruction of beams. Therefore, six-electrode BPMs with circular and quasi-ellipse cross-sections have been developed on the basis of a newly introduced theory. A low-noise signal processor for the six-electrode BPM has also been developed to perform fine measurement. We expected the following resolutions determined by the S/N ratio of the circuit; the first order moments (beam positions) > 1 μm, and the second order moments with a size > 110 μm. The first beam test was carried out using the six-electrode BPM with circular cross-section and the old signal processor. The measured sensitivities and resolutions of the second-order moments showed good agreement with the theory.  
slides icon Slides TUPLB09 [8.248 MB]  
 
TUPLB10 Non-destructive Real-time Monitor to Measure 3D-bunch Charge Distribution with Arrival Timing to Maximize 3D Overlapping for HHG-seeded EUV-FEL 467
 
  • H. Tomizawa, K. Ogawa, T. Sato, M. Yabashi
    RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
  • M. Aoyama
    JAEA/Kansai, Kyoto, Japan
  • A. Iwasaki, S. Owada
    The University of Tokyo, Tokyo, Japan
  • S. Matsubara, Y. Okayasu, T. Togashi
    JASRI/SPring-8, Hyogo, Japan
  • T. Matsukawa, H. Minamide
    RIKEN ASI, Sendai, Miyagi, Japan
  • E. Takahashi
    RIKEN, Saitama, Japan
 
  Non-destructive, shot-by-shot real-time monitors have been developed to measure 3D bunch charge distribution (BCD). This 3D monitor has been developed to monitor 3-D overlapping electron bunches and higher harmonic generation (HHG) pulses in a seeded VUV-FEL. This ambitious monitor is based on an Electro-Optic (EO) multiple sampling technique in a manner of spectral decoding that is non-destructive and enables real-time measurements of the longitudinal and transverse BCD. This monitor was materialized in simultaneously probing eight EO crystals that surround the electron beam axis with a radial polarized and hollow EO-probe laser pulse. In 2009, the concept of 3D-BCD monitor was verified through electron bunch measurements at SPring-8. The further target of the temporal resolution is ~30 fs (FWHM), utilizing an organic EO crystal (DAST) instead of conventional inorganic EO crystals (ZnTe, GaP, etc.) The EO-sampling with DAST crystal is expected to measure a bunch length less than 30 fs (FWHM). In 2011, the first bunch measurement with an organic EO crystal (DAST) was successfully demonstrated in the VUV-FEL accelerator at SPring-8.  
slides icon Slides TUPLB10 [2.713 MB]  
 
TUPB079 Design and Beam Test of Six-Electrode BPMs for Second-Order Moment Measurement 654
 
  • K. Yanagida, H. Hanaki, S. Suzuki
    JASRI/SPring-8, Hyogo-ken, Japan
 
  In the SPring-8 linac, four-electrode beam position monitors (BPMs) have been utilized for the measurement of the transverse first-order moments, which correspond to the centroids of beam charge distributions. We have planed to measure the transverse second-order moments of beams to obtain information of beam optics and its energy deviations during the top-up beam injection without destruction of beams. Therefore, six-electrode BPMs with circular and quasi-ellipse cross-sections have been developed on the basis of a newly introduced theory. A low-noise signal processor for the six-electrode BPM has also been developed to perform fine measurement. We expected the following resolutions determined by the S/N ratio of the circuit; the first order moments (beam positions) >1 μm, and the second order moments with a size >110 μm. The first beam test was carried out using the six-electrode BPM with circular cross-section and the old signal processor. The measured sensitivities and resolutions of the second-order moments showed good agreement with the theory.  
 
TUPB080 Non-destructive Real-time Monitor to Measure 3D Bunch Charge Distribution with Arrival Timing to Maximize 3D Overlapping for HHG-Seeded EUV-FEL 657
 
  • H. Tomizawa, K. Ogawa, T. Sato, M. Yabashi
    RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
  • M. Aoyama
    JAEA/Kansai, Kyoto, Japan
  • A. Iwasaki, S. Owada
    The University of Tokyo, Tokyo, Japan
  • S. Matsubara, Y. Okayasu, T. Togashi
    JASRI/SPring-8, Hyogo, Japan
  • T. Matsukawa, H. Minamide
    RIKEN ASI, Sendai, Miyagi, Japan
  • E. Takahashi
    RIKEN, Saitama, Japan
 
  Non-destructive, shot-by-shot real-time monitors have been developed to measure 3D bunch charge distribution (BCD). This 3D monitor has been developed to monitor 3D overlapping electron bunches and higher harmonic generation (HH) pulses in a seeded VUV-FEL. This ambitious monitor is based on an Electro-Optic (EO) multiple sampling technique in a manner of spectral decoding that is non-destructive and enables real-time measurements of the longitudinal and transverse BCD. This monitor was materialized in simultaneously probing eight EO crystals that surround the electron beam axis with a radial polarized and hollow EO-probe laser pulse. In 2009, the concept of 3D-BCD monitor was verified through electron bunch measurements at SPring-8. The further target of the temporal resolution is ~30 fs (FWHM), utilizing an organic EO crystal (DAST) instead of conventional inorganic EO crystals (ZnTe, GaP, etc.) The EO-sampling with DAST crystal is expected to measure a bunch length less than 30 fs (FWHM). In 2011, the first bunch measurement with an organic EO crystal (DAST) was successfully demonstrated in the VUV-FEL accelerator at SPring-8.  
 
TUPB081 Beam Diagnostics Development for Triumf E-Linac 660
 
  • V.A. Verzilov, P.S. Birney, D.P. Cameron, J.V. Holek, S.Y. Kajioka, S. Kellogg, M. Lenckowski, M. Minato, W.R. Rawnsley
    TRIUMF, Vancouver, Canada
  • J.M. Abernathy, D. Karlen, D.W. Storey
    Victoria University, Victoria, B.C., Canada
 
  TRIUMF laboratory is currently in a phase of the construction of a new superconducting 50 MeV 10 mA cw electron linac (e-linac) to drive photo-fission based rare radioactive isotope beam (RIB) production. The project imposes certain technical challenges on various accelerator systems including beam diagnostics. In the first place these are a high beam power and strongly varying operating modes ranging from very short beam pulses to the cw regime. A number of development projects have been started to construct the diagnostics instrumentation required for commissioning and operation of the facility. The paper reports the present status of the projects along with measurement results obtained at the test facility which produced the first beam in Fall of 2011.  
 
TUPB082 Beam Loss Track Measurements by a Fast Trigger Scheme in J-PARC Linac 663
 
  • H. Sako, T. Maruta, A. Miura
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
 
  Funding: Work partially supported by Grant-in-Aid for Challenging Exploratory Research
In J-PARC Linac, highest beam loss has been observed at the ACS (Annular-Coupled Structure linac) section. The primary source of the beam loss is considered to be H0 produced by an interaction of H beams with remnant gas. The H0 hits the beam duct, converted to H+, and escapes from the beam duct. To detect the H+'s and estimate the absolute magnitude of the beam loss, we constructed a detector system, which consists of 6 planes of hodoscopes made of 16 scintillation fibers with 64 x 64 mm2 area. The scintillation light is measured by multi-anode photomultipliers. In the ACS section, two planes to measure horizontal positions are installed, and at about 1 m downstream positions, two planes for horizontal measurements and two for vertical measurements are placed. We will reconstruct charged particles passing through all the 6 planes, and measure the velocity by time-of-flight and energy loss to identify particle species. We present new measurements since the recovery of the J-PARC after the earthquake started in April 2012 by a new fast trigger scheme using dynode signals of photomultipliers in order to improve signal-to-noise ratios.
 
 
TUPB084 High Dynamic-Range High Speed Linac Current Measurements 666
 
  • C. Deibele
    ORNL, Oak Ridge, Tennessee, USA
  • D. Curry, R. Dickson
    ORNL RAD, Oak Ridge, Tennessee, USA
 
  Funding: ORNL is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy.
It is desired to measure the linac current of a charged particle beam with a consistent accuracy over a dynamic range of over 120 dB. Conventional current transformers suffer from droop, can be susceptible to electromagnetic interference (EMI), and can be bandwidth limited. A novel detector and electronics were designed to maximize dynamic range of about 120 dB and measure risetimes on the order of 10 nanoseconds.
 
 
TUPB102 Design and Performances of Phase Monitor in J-PARC Linac 699
 
  • A. Miura
    JAEA/J-PARC, Tokai-mura, Japan
  • Z. Igarashi, T. Miyao
    KEK, Ibaraki, Japan
 
  J-PARC linac employs a fast current transformer (FCT) as a beam phase monitor to calculate the beam energy by time-of-flight method. We have installed and used 61 FCTs in the current beam line. Because the phase measurements at additional 41 points in the future ACS sections are required for the energy upgrade project with adding 21 ACS (Annular Coupled Structure) cavities, we stared the design and fabrication of FCTs as the phase measurement devices. In addition, J-PARC linac employs the 4-stripline beam position monitors (BPMs) for the beam position measurement. It has been considered that the signals from striplines of BPM would be useful for a phase measurement. A phase measurement using a BPM has been successfully conducted. In order to evaluate the performances of the FCT, the signal sensitivity and cut-off frequency of newly fabricated FCT are measured. Also, these data of the BPM are also measured to be compared with the data of FCT. Based on the results of the comparing both measurements, the superiority of both monitors for beam phase measurement is discussed.