Author: Forck, P.
Paper Title Page
MOPC21 Layout of the BPM System for p-LINAC at FAIR and the Digital Methods for Beam Position and Phase Monitoring 101
  • M.H. Almalki, G. Clemente, P. Forck, L. Groening, W. Kaufmann, P. Kowina, C. Krüger, R. Singh
    GSI, Darmstadt, Germany
  • W. Ackermann
    TEMF, TU Darmstadt, Darmstadt, Germany
  • M.H. Almalki
    IAP, Frankfurt am Main, Germany
  • M.H. Almalki
    KACST, Riyadh, Kingdom of Saudi Arabia
  • B.B. Baricevic, R. Hrovatin, P.L. Lemut, M. Znidarcic
    I-Tech, Solkan, Slovenia
  • C.S. Simon
    CEA/DSM/IRFU, France
  The planned Proton LINAC at the FAIR facility will provide a beam current from 35 to 70 mA accelerated to 70 MeV by novel CH-type DTLs. Four-fold button Beam Position Monitor (BPM) will be installed at 14 locations along the LINAC and some of these BPMs are mounted only about 40 mm upstream of the CH cavities. The coupling of the RF accelerating field to the BPMs installed close to the CH cavities was numerically investigated. For the digital signal processing using I/Q demodulation a 'Libera Single Pass H' is foreseen. The properties of this digitization and processing scheme were characterized by detailed lab-based tests. Moreover, the performance was investigated by a 80 μA Ne4+ beam at 1.4 MeV / u and compared to a time-domain approach and successive FFT calculation. In particular, concerning the phase determination significant deviations between the methods were observed and further investigations to understand the reason are ongoing.  
poster icon Poster MOPC21 [1.622 MB]  
MOPC36 Test of a Non-Invasive Bunch Shape Monitor at GSI High Current LINAC 151
  • P. Forck, C. Dorn, O.K. Kester, P. Kowina, B. Zwicker
    GSI, Darmstadt, Germany
  • O.K. Kester
    IAP, Frankfurt am Main, Germany
  Funding: The work is funded by European Union FP7 within CRISP.
At the heavy ion LINAC at GSI, a novel scheme of non-invasive Bunch Shape Monitor has been tested with several ion beams at 11.4 MeV/u. The monitor’s principle is based on the analysis of secondary electrons as liberated from the residual gas by the beam impact. These electrons are accelerated by an electrostatic field, transported through a sophisticated electrostatic energy analyzer and an RF-deflector, acting as a time-to-space converter. Finally a MCP amplifies electrons and with a CCD camera the electron distribution is detected. For the applied beam settings this Bunch Shape Monitor is able to obtain longitudinal profiles down to a width of 400 ps with a resolution of 50 ps, corresponding to 2 degree of the 108 MHz accelerating frequency. Systematic parameter studies for the device were performed to demonstrate the applicability and to determine its resolution. The achievements and ongoing improvements for the monitor are discussed.
poster icon Poster MOPC36 [2.665 MB]  
MOPF13 Transverse Beam Profiling for FAIR 232
  • M. Schwickert, C.A. Andre, F. Becker, P. Forck, T. Giacomini, E. Gütlich, T. Hoffmann, A. Lieberwirth, S. Löchner, A. Reiter, B. Voss, B. Walasek-Höhne, M. Witthaus
    GSI, Darmstadt, Germany
  The FAIR facility will provide intense primary beams of protons and heavy ions, or secondary beams of antiproton and rare isotopes. The operation includes fixed-target experiments or subsequent facilities of independent storage rings and experiment beam lines. The particle beams greatly differ in ion species, intensity, time structure, spot size and stopping power. Therefore, transverse beam profile measurements require a careful choice of detector type for each location in order to cope with the large dynamic range and operational demands. This contribution presents the actual status of FAIR detector developments for intercepting devices (SEM-Grids, Multi-Wire Proportional Chambers, Scintillating Screens) as well as non-intercepting Beam Induced Fluorescence Monitors and Ionization Profile Monitors. Recently, promising results were obtained with slow extracted heavy ion beams in measurements of optical transmission radiation emitted from thin metal foils. The boundaries for the application area are described and basic detector parameters are summarized.  
MOPF14 Scintillation Screen Response to Heavy Ion Impact 235
  • E. Gütlich, O.K. Kester
    IAP, Frankfurt am Main, Germany
  • P. Forck, O.K. Kester
    GSI, Darmstadt, Germany
  For quantitative transverse ion beam profile measurement, imaging properties of scintillation screens have been investigated for the working conditions of the GSI linear accelerator. In the ion energy range between 4.8 and 11.4 MeV/u the imaging properties of the screens are compared with profiles obtained using standard techniques like SEM grids and scraper. Detailed investigations with e.g. Calcium and Argon ion beams on various radiation-hard materials show that the measured beam profiles can differ from those measured with standard methods and depend on several beam and material parameters *. For the practical usage of scintillators, it is necessary to have predictions for the response of the scintillator to a given ion beam. An existing model for the light output of scintillators for single particle irradiation has been extended to include the effect of overlapping excitation tracks. To validate the model, dedicated measurements with well-defined Carbon and Titanium ion beams at 11.4 MeV/u have been carried out. To understand the mechanisms, the beam flux and the pulse length has been varied. The measured light yield is compared to the model calculations.
* E. Gütlich et al., “Scintillation screen studies for high dose ion beam applications”, IEEE Transactions on Nuclear Science, Vol. 59, No. 5, October 2012, pp. 2354 – 2359.
poster icon Poster MOPF14 [0.818 MB]  
TUPF21 Response of Scintillating Screens to Fast and Slow Extracted Ion Beams 553
  • A. Lieberwirth, W. Ensinger
    TU Darmstadt, Darmstadt, Germany
  • P. Forck, B. Walasek-Höhne
    GSI, Darmstadt, Germany
  Funding: Funded by German Ministry of Science (BMBF), contract number 05P12RDRBJ
For the FAIR project, imaging properties of inorganic scintillators for high energetic heavy ion beams were studied. In order to investigate the characteristics of scintillation response and transverse beam profile, several experiments were conducted with slow (200 ms) and fast (1 μs) extracted 350 MeV/u Uranium beams from SIS18. The extracted particle number was varied between 105 and 109 particles per pulse for the irradiation of seven different scintillators: YAG:Ce-crystals with different qualities, pure and Cr-doped alumina as well as two phosphors P43 and P46. Additionally radiation resistance tests for all phosphor screens and the Cr-doped alumina screen were performed by irradiating with more than 700 pulses with 109 ions each. Linear response in scintillation light output as well as realistic statistical moments over the large range of ion intensities are presented for each material. Only minor changing in target response was observed after 45 minutes of permanent irradiation.
poster icon Poster TUPF21 [2.601 MB]  
THAL1 Understanding the Tune Spectrum of High Intensity Beams 914
  • R. Singh, O. Chorniy, P. Forck, R. Haseitl, W. Kaufmann, P. Kowina, K. Lang
    GSI, Darmstadt, Germany
  • R. Singh
    TEMF, TU Darmstadt, Darmstadt, Germany
  Tune spectra measurements are routinely performed in most synchrotrons. At high intensity and low energies (i.e. γ≈1), space charge effects can significantly modify the tune spectra in comparison to the classical low intensity spectra. Systematic studies were performed at GSI SIS-18 to observe these characteristic modifications, mainly resulting from the shift of the head-tail modes in direct dependence of beam intensity and synchrotron tune frequency. In this contribution, an interpretation of the tune spectra modification based on quasi-analytical models and numerical simulations will be presented. Extraction of elusive beam parameters such as incoherent tune shift, machine impedances, chromaticity, etc. from the spectra will be demonstrated. Further, the applications and relevance of these results for other synchrotrons will be discussed.  
slides icon Slides THAL1 [3.807 MB]