A   B   C   D   E   F   G   H   I   K   L   M   N   O   P   R   S   T   U   W    

beam-losses

Paper Title Other Keywords Page
IT10 Advanced Diagnostics of Lattice Parameters in Hadron Colliders collider, diagnostics, instrumentation, lattice 45
 
  • J.-P. Koutchouk
    CERN, Geneva, Switzerland
  With a beam stored energy exceeding by several orders of magnitude the quench level of the magnets and non-negligible non-linear field components, the control of the beam dynamics and losses in LHC must be very precise. This is a strong incentive to strengthen as much as possible the potential of beam diagnostics. This paper reviews some of the developments in various laboratories that appear to have a large potential. They either allow for a much better access to classical beam parameters or for the measurement of quantities formerly not accessible. Examples are a fast measurement of the betatron tunes, the use of PLL for reliable tune tracking and feedback, new methods or ideas to measure the chromaticity with the potential of feedback systems and similarly for the betatron coupling, the measurement of high-order non-linear fields and resonances and the potential of AC dipole excitation. This list is bound to be incomplete as the field is fortunately very dynamic.  
 
CT05 Beam Loss Detection at Radiation Source ELBE diagnostics, instrumentation, linac, electron, radiation, beam-transport 65
 
  • P. Michel, J. Teichert, R. Schurig, H. Langenhagen
    FZR, Forschungszentrum Rossendorf, Dresden, Germany
  The Rossendorf superconducting Electron Linac of high Brilliance and low Emittance (ELBE) delivers an 40 MeV, 1 mA cw-beam for different applications such as bremsstrahlung production, electron channelling, free-electron lasers or secondary particle beam generation. In this energy region in case of collisions of the electron beam with the pipe nearly all beam power will be deposited into the pipe material. Therefore a reliable beam loss monitoring is essential for machine protection at ELBE. Different systems basing on photo multipliers, compton diodes and long ionization chambers were studied. The pros and cons of the different systems will be discussed. Ionization chambers based on air-isolated RF cables installed some cm away parallel to the beam line turned out to be the optimal solution. The beam shut-off threshold was adjusted to 1 μC integral charge loss during a 100 ms time interval. Due to the favourable geometry the monitor sensitivity varies less than ±50% along the beam line (different shielding conditions).  
 
PT19 Transverse Feedback System For The Cooler Synchrotron COSY-Jülich - First Results storage-ring, synchrotron, beam cooling, coherent-effects, damping, feedback, kicker, pick-up 214
 
  • V. Kamerdzhiev, J. Dietrich, I. Mohos
    IKP, Forschungszentrum Jülich GmbH, Jülich, Germany
  The cooler synchrotron COSY delivers unpolarized and polarized protons and deuterons in the momentum range 300 MeV/c up to 3.65 GeV/c. Electron cooling at injection level and stochastic cooling covering the range from 1.5 GeV/c up to maximum momentum are available to prepare high precision beams for internal as well as for external experiments in hadron physics. In case of electron cooled beam the intensity is limited by transverse instabilities. The major losses are due to the vertical coherent beam oscillations. To damp these instabilities a transverse feedback system is under construction. First results with a simple feedback system are presented. Due to the feedback system operation the intensity and lifetime of the electron cooled proton beam at injection energy could be significantly increased. Measurements in frequency and time domain illustrate the performance of the system.  
 
PT30 Ionisation Chambers for the LHC Beam Loss Detection instrumentation, radiation 245
 
  • E. Gschwendtner, R. Assmann, B. Dehning, G. Ferioli, V. Kain
    CERN, Geneva, Switzerland
  At the Large Hadron Collider (LHC) a beam loss system will be used to prevent and protect superconducting magnets against coil quenches and coil damages. Since the stored particle beam intensity is 8 orders of magnitude larger than the lowest quench level value particular attention is paid to the design of the secondary particle shower detectors. The foreseen ionisation chambers are optimised in geometry simulating the probable loss distribution along the magnets and convoluting the loss distribution with the secondary particle shower distributions. To reach the appropriate coverage of a particle loss and to determine the quench levels with a relative accuracy of 2 the number of the detectors and their lengths is weighted against the particle intensity density variation. In addition attention is paid to the electrical ionisation chamber signal to minimise the ion tail extension. This optimisation is based on time resolved test measurements in the PS booster. A proposal for a new ionisation chamber will be presented.  
 
PT31 Optical Fibre Dosimeter for SASE FEL Undulators diagnostics, free-electron-laser, instrumentation, optics 248
 
  • M. Körfer
    DESY, Deutsches Elektronen-Synchrotron, Hamburg, Germany
  • H. Henschel, J. Kuhnhenn
    Fraunhofer-INT, Fraunhofer-INT, Euskirchen, Germany
  • F. Wulf
    HMI, Hahn-Meitner Institut, Berlin, Germany
  Single pass Free Electron Lasers (FELs) based on self-amplified spontaneous emission (SASE) are developed for high brightness and short wavelength applications. They use permanent magnet undulators which are radiation sensitive devices. During accelerator commissioning beam losses can appear anywhere along the undulator line. To avoid damage of the permanent magnets due to radiation, an optical fibre dosimeter system can be used. The increase of absorption caused by ionizing radiation is measured in radiation sensitive optical fibers. The dose system enables relatively fast particle loss tuning during accelerator operation and allows the monitoring of the accumulated dose. Dose measurements in narrow gaps which are inaccessible for any other (online) dosimeter type become possible. The electromagnetic insensitivity of optical fibre sensor is an advantage of applications in strong magnetic undulator fields. At each location the light absorption is measured by using an optical power-meter. The dynamic range is about 50 dB and covers the linear range of the dose calibration of the fibre. The resolution of the system is 140 mGy. The time between successive measurements is about 5 minutes. The system was installed and successfully tested at the TESLA Test Facility TTF1. The fibre sensors will be a standard diagnostic tool in the soft X-ray user facility TTF2.  
 
PT32 Beam Loss Diagnostics Based on Pressure Measurements beam diagnostics, heavy ion beam, instrumentation, synchrotron 251
 
  • E. Badura, B. Franczak, W. Kaufmann, P. Horn, H. Reeg, H. Reich-Sprenger, P. Schütt, P. Spiller, K. Welzel, U. Weinrich
    GSI, Gesellschaft für Schwerionenforschung, Darmstadt, Germany
  The GSI is operating a heavy ion synchrotron, which is currently undergoing an upgrade towards higher beam intensities. It was discovered that beam losses induce a significant pressure increase in the vacuum system. In order to detect the time constants of the pressure increase and decrease, fast total pressure measurements were put into operation. With the recently installed partial pressure diagnostics it is also possible to follow up which types of molecules are released. The presentation will focus on the different techniques applied as well as on some measurement results. The potential and difficulties of this diagnostic tool will also be discussed.