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BE-BI-PM Section


Beam Halo Monitor

In future high intensity, high energy accelerators, beam loss has to be minimized to maximize performance and reduce activation of accelerator components. It is imperative to have a clear understanding of the mechanisms that can lead to halo formation and to have the possibility to test available theoretical models with an adequate experimental setup. Measurements based on optical transition radiation (OTR) provide an interesting opportunity for high resolution measurements of the transverse beam profile. In order to be applicable for measurements within the beam halo region, it is of utmost importance that a high dynamic range is covered by the image acquisition system.

With the aim to simulate a light distribution that comes close to what is expected in CTF3, an Opto-Electronics PLS20 pulsed diode laser was used in our lab for first tests. For image acquisition, three different techniques were used:

  • A standard 8-bit CCD camera as it is used in all present installations at CTF3. To adapt the measurement to the available light level, optical density filters were used for optimization of the image,
  • a small Hamamatsu photomultiplier tube (PMT) type R7400U was installed in a metallic box with a circular aperture variable in diameter between 0.3 mm and 2 mm. The step size for translation of the PMT in horizontal and vertical direction was 100 um for the measurements,
  • A SpectraCAM® system from Thermo Electron Corporation, based on CID technology.

Details about the measurements can be found in the publications below. A summary of the measurements is shown in the following plot.


Related documents

  • C.P. Welsch, E. Bravin, B. Burel, T. Chapman, T. Lefèvre, M.J. Pilon,” Alternative Techniques for Beam Halo Measurements”, Meas. Sci. Technol. 17 (2006) 2035c and CERN-AB-2006-23
  • C.P. Welsch, E. Bravin, B. Burel, T. Lefèvre, T. Chapman, M. Pilon,”High Dynamic Range Beam Profile Measurements”, Proc. Europ. Part. Acc. Conf., Edinburgh, Scotland (2006), CERN-AB-2006-068, CLIC note 686 and CTF3 note 081
  • C.P. Welsch, E. Bravin, B. Burel, T. Lefèvre,”Operational Experience with a SpectraCAM CID camera system”, CLIC note 657 and CERN-OPEN-2006-018, CERN, Geneva (2006)
  • C.P. Welsch, H. Braun, E. Bravin, R. Corsini, T. Lefevre, D. Schulte, F. Tecker, ”Design Alternatives for Beam Halo Monitors in High Intensity Accelerators”, Proc. DIPAC, Lyon, France (2005), CERN-AB-2005-066 and CLIC note 660
  • T. Lefèvre; H.-H. Braun; E. Bravin; R. Corsini; A.L. Perrot; D. Schulte,”Beam Halo Monitoring at CTF3”, Proc. Europ. Part. Acc. Conf., Lucerne, Switzerland (2005), CERN-AB-2004-091 and CLIC-Note-610
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Page last modified on October 04, 2006, at 09:00 AM EST