Author: Rassool, R.P.
Paper Title Page
MOPC20 Application of Metal-Semiconductor-Metal (MSM) Photodetectors for Transverse and Longitudinal Intra-Bunch Beam Diagnostics 97
  • R.J. Steinhagen
    CERN, Geneva, Switzerland
  • M.J. Boland
    SLSA, Clayton, Australia
  • T.G. Lucas, R.P. Rassool
    The University of Melbourne, Melbourne, Australia
  • T.M. Mitsuhashi
    KEK, Ibaraki, Japan
  The performance reach of modern accelerators is often governed by the ability to reliably measure and control the beam stability. In high-brightness lepton and high-energy hadron accelerators the use of optical diagnostic techniques for this purpose is becoming more widespread as the required bandwidth, resolution and high RF beam power level involved limit the use of traditional electro-magnetic RF pick-up based methods. This contribution discusses the use of fibre-coupled ultra-fast Metal-Semiconductor-Metal Photodetectors (MSM-PD) as an alternative, dependable means to measure signals deriving from electro-optical and synchrotron-light based diagnostics systems. It describes the beam studies performed at CERN's CLIC Test Facility (CTF3) and the Australian Synchrotron to assess the feasibility of this technology as a robust, wide-band and sensitive technique for measuring transverse intra-bunch and bunch-by-bunch beam oscillations, longitudinal beam profiles, un-bunched beam population and beam-halo profiles. The used amplification schemes, achieved sensitivities, linearity, and dynamic range of the detector setup are presented.  
poster icon Poster MOPC20 [3.065 MB]  
TUPF18 Vertical Undulator Emittance Measurement: A Statistical Approach 543
  • K.P. Wootton, R.P. Rassool
    The University of Melbourne, Melbourne, Australia
  • M.J. Boland, B.C.C. Cowie, R.T. Dowd
    SLSA, Clayton, Australia
  Direct measurement of low vertical emittance in storage rings is typically achieved via interferometric techniques. Proof of low vertical emittance is demonstrated by the measurement of a null radiation field, which is also the crux of the vertical undulator emittance measurement. Here we present strategies to improve the sensitivity to low vertical emittance beams. We move away from photon spectrum analysis to a statistical analysis of undulator radiation, showing the measured increase in signal-to-background. Reproducing simulations of previous work, we demonstrate that photon beam polarisation extends the linearity of the technique by several decades in emittance. These statistical and polarisation improvements to the signal-to-background allow realistic measurement of smallest vertical emittance.  
poster icon Poster TUPF18 [2.090 MB]  
TUPF19 APPLE-II Undulator Magnetic Fields Characterised from Undulator Radiation 546
  • K.P. Wootton, R.P. Rassool
    The University of Melbourne, Melbourne, Australia
  • M.J. Boland, B.C.C. Cowie
    SLSA, Clayton, Australia
  The spatial profile of APPLE-II undulator radiation has been measured at high undulator deflection parameter, high harmonic and very small emittance. Undulators are typically designed to operate with small deflection parameter to push the fundamental mode to high photon energies. This unusual choice of parameters is desirable for measurement of vertical emittance with a vertical undulator. We present 1-D and 2-D measured profiles of undulator radiation, and show that this is reproduced in numerical models using the measured magnetic field of the insertion device. Importantly these measurements confirm that for these parameters, the spatial intensity distribution departs significantly from usual Gaussian approximations, instead resembling a double-slit diffraction pattern. This could be an important consideration for photon beamlines of ultimate storage ring light sources.  
poster icon Poster TUPF19 [2.364 MB]