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TUP076 Status of Beam Loss Evaluation at J-PARC Linac beam-losses, linac, proton, cavity 590
 
  • A. Miura, N. Kikuzawa, T. Maruta, K. Yamamoto
    JAEA/J-PARC, Tokai-mura
  • Z. Igarashi, T. Miyao
    KEK, Ibaraki
  • M. Ikegami
    J-PARC, KEK & JAEA, Ibaraki-ken
  • H. Sako
    JAEA, Ibaraki-ken
  • S. Sato
    JAEA/LINAC, Ibaraki-ken
 
 

Since November, 2007, J-PARC Linac has been operated at 7.2kW beam power. During the operation, beam losses possibly caused by the H0 particles generated by the interaction between H- beam and residual gas in the transport line were observed in the SDTL (Separated-type Drift-Tube Linac) section. In the linac operation, Ar-CO2 gas proportional counters are employed for the measurement of beam loss, but they are also sensitive to background noise of X-ray emitted from RF cavities. In this section, protons, secondary hadrons and gamma rays would be mainly generated as a beam loss, but it is not easy to estimate real beam loss using the proportional counter. The plastic scintillation counters with less X-ray sensitivity and 3He proportional counters with high thermal neutron sensitivity will be also employed to measure the beam loss. The combination of these detectors would bring more accurate beam loss measurements with suppression of X-ray noise. A measurement of emission position and angle distributions of protons due to H- beam loss is being planed. This result would lead to clarify the source of beam loss. This paper reports status of beam loss evaluation using these detectors.

 
TUP099 Coherent Diffraction Radiation as a Tool for Longitudinal Beam Profile Diagnostics at CTF3. target, radiation, electron, simulation 644
 
  • K. Lekomtsev, G.A. Blair, G.E. Boorman, V. Karataev, M. Micheler
    JAI, Egham, Surrey
  • R. Corsini, T. Lefèvre
    CERN, Geneva
 
 

Compact Linear Collider (CLIC) is a multi-TeV electron-positron collider for particle physics based on an innovative two-beam acceleration scheme. The CLIC Test Facility 3 (CTF3, CERN) aims to demonstrate feasibility of this concept. The monitoring of a longitudinal profile will be very important for the CLIC. The optimization of the longitudinal charge distribution in a bunch is crucial for the maximisation of the luminosity and also for an optimal performance of a CLIC drive beam. A setup for the investigation of Coherent Diffraction Radiation (CDR) from targets with various configurations as a tool for non-invasive longitudinal electron beam profile diagnostics has been designed and installed in the CRM line of the CTF3 [1, 2]. In this report we present the status of the experiment and results on interferometric measurements of CDR from a single target configuration. Studies on downstream background contribution in the CRM line have been performed. Recently we have upgraded the system by installing a second target. In this report we shall also demonstrate the results on simulations of CDR spatial distribution from the two target configuration.


[1] M. Micheler et al., Longitudinal Beam Profile Measurements at CTF3 using CDR, PAC'09, "**".
[2] M. Micheler et al., Longitudinal beam profile monitor at CTF3 based on CDR, RREPS-09, "**".

 
TUP102 Phase Space Analysis at the SwissFEL Injector Test Facility emittance, gun, diagnostics, electron 653
 
  • B. Beutner, R. Ischebeck, T. Schietinger
    PSI, Villigen
 
 

Phase I of the SwissFEL Injector Test Facility consists of a 2.6-cell S-band RF gun, a spectrometer, and a series of transverse beam diagnostic systems such as YAG screens, slit and pepper-pot masks. Its primary purpose is the demonstration of a high-brightness electron beam meeting the specifications of the SwissFEL main linac. Phase space characterization at beam energies up to 7 MeV, where space charge still dominates, is performed with YAG screens in combination with slit- and pinhole (pepper-pot) masks. Advanced image analysis is used to mitigate artefacts due to background, pixel readout noise, or dark current. We present our data analysis procedure for the slit scan method, with particular emphasis on image processing and its effect on the reconstructed emittance. Pepper-pot measurements using an independent analysis framework are used to cross-check the slit scan results.

 
THP069 Stripping of H-minus Beams by Residual Gas in the Linac at the Los Alamos Neutron Science Center proton, linac, ion, vacuum 908
 
  • R.C. McCrady
    LANL, Los Alamos, New Mexico
 
 

The linear accelerator at the Los Alamos Neutron Science Center (LANSCE) accelerates both protons and H-minius ions using Cockroft-Walton-type injectors, a drift-tube linac and a side-coupled linac. The vacuum is maintained in the range of 10-6 to 10-7 Torr; the residual gas in the vacuum system results in some stripping of the electrons from the H-minus ions resulting in beam spill and the potential for unwanted proton beams delivered to experiments. We have measured the amount of fully-stripped H-minus beam (protons) that ends up at approximately 800MeV in the beam switchyard at LANSCE using image plates as very sensitive detectors. I will present the motivation for the measurement, the measurement technique and results, and calculations to model the results and possible mitigation schemes.