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emittance

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IT11 Beam Diagnostics, Old and New
This is essentially a repeat of 'Beam Diagnostics Revisited', invited talk given at EPAC, Stockholm, June 1998
diagnostics, ion, linac, injection 33
 
  • H. Koziol
    CERN, Geneva, Switzerland
  The performance of accelerators and storage rings depends critically on the completeness and quality of their beam diagnostic systems. It is essential to equip them from inception with all the instruments providing the information on the properties and the behaviour of the beams, needed during running-in, in operation, and for development of performance towards the design goal and often well beyond. Most of the instruments have proven their worth since decades, but their power has been increased through the modern means of data acquisition and treatment. A few new instruments have made their appearance in recent years, some still under development and scrutiny for their operational value and precision. The multi-accelerator chains of today’s and tomorrow’s big colliders have tight tolerances on beam loss and emittance blow-up. For beam diagnostics this means a great challenge for precision and consistency of measurements all along the chain.  
 
CT01 Measurements with a versatile Test Bench for Commissioning of the new GSI High Current Linac rfq, ion, pick-up, diagnostics 45
 
  • P. Forck, P. Strehl
    GSI, Gesellschaft für Schwerionenforschung, Darmstadt, Germany
  For the commissioning of the new GSI prestripper a conventional slitdetector system and a single shot pepperpot system has been installed on a mobile test bench to measure intensity distributions in the two transverse phase spaces. To determine intensity distributions in the longitudinal phase space, including beam energy capacitive pickups and newly developed diamond counters have been installed on the test bench. The setup of the test bench provides also redundant information for beam current, beam profile and beam position. The most important features of all measuring systems including signal processing and data evaluation are reported. First results from the commissioning of the upgraded prestripper of the UNILAC at GSI are reported.  
 
CT02 Determination of Radial Ion Beam Profile from the Energy Spectrum of Residual Gas Ions Accelerated in the Beam Potential space-charge, ion, electron, acceleration 50
 
  • R. Dölling
    IAP, Institut für angewandte Physik der Johann Wolfgang Goethe Universität
  Residual gas ions (RGI) created from collisions of positive beam ions (BI) with residual gas atoms are accelerated out of the ion beam by its space charge potential. It is demonstrated that with one-dimensional radial symmetry the radial distributions of BI density and space charge potential can be determined from the energy distribution of RGI radially leaving the beam tube. RGI energy spectra were taken with an electrostatic analyser of Hughes-Rojansky type on a 10 keV 1.5 mA He+ beam. For comparison the radial BI density distribution was determined with a radial wire probe, an electron beam probe and a beam transport calculation based on an emittance measurement located downstream.  
 
CT11 The OTR Screen Betatron Matching Monitor of the CERN SPS injection, betatron, optics, scattering 90
 
  • C. Bovet, R.J. Colchester, G. Ferioli, J.J. Gras, R. Jung, J.M. Vouillot
    CERN, Geneva, Switzerland
  In order to satisfy the stringent emittance requirements of LHC, betatron matching monitors, based on multiturn beam profile measurements, have been proposed for the SPS and LHC. A test monitor has been installed for evaluation in the CERN SPS first in 1996 and improved in 1997. It is based on an OTR screen and a fast beam profile acquisition system. It has been used with proton beams to assess the quality of the betatron matching from the PS to the SPS in 1998. Experience and results are presented.  
 
PS04 Influence of transverse beam dimensions on beam position monitor signals pick-up, quadrupole, synchrotron, instrumentation 106
 
  • A. Jankowiak, T. Weis
    DELTA, Institute for Accelerator Physics and Synchrotron Radiation, University of Dortmund, Germany
  In this paper we will evaluate the influence of transverse beam dimensions on the signal functions of a beam position monitor (BPM) with capacitive pick-up electrodes. The error which occurs in the determination of the beam position when disregarding these effects is calculated as an example for the DELTA1 BPM. The possibility to use this effect for the measurement of the beam size / emittance is discussed.  
 
PS13 Analysis of the proton beam in the DESY transport lines by video readout proton, background, luminosity, vacuum 129
 
  • F. Solodovnik, T. Limberg, K. Wittenburg
    IHEP, Institute for High Energy Physics, Protvino, Russia
  Injection efficiency, beam optic matching and emittance preservation are very important parameters in achieving a high luminosity in large proton accelerators. We improved the analysing system of the phosphor screen readout of the proton transport lines in the accelerator chain of HERA with respect to the parameters above. The screens are read out by simple CCD video cameras. The signals are stored in local frame grabbers. An analogue output of the stored image is multiplexed and read-out by a fast PCI frame grabber card in a PC. The beam orbit and the beam emittance can be measured from each screen. A Visual Basic program is used to displays the trajectory and the envelope of the beam from a single transfer. The same program helps to drive bumps to achieve a proper steering through the line. The beam width can be measured from selected screens to calculate the emittance and other beam parameters including their errors. The read out and analysing system will be described and measurements will be shown.  
 
PT07 Emittance measurements at the new UNILAC-pre-stripper using a pepper-pot with a PC-controlled CCD-camera ion, laser, linac, ion-source 171
 
  • M. Dolinska, M. Domke, P. Forck, T. Hoffmann, D. Liakin, A. Peters, P. Strehl
    GSI, Gesellschaft für Schwerionenforschung, Darmstadt, Germany
  The complex mathematical algorithms and procedures to extract emittance data from intensity distributions measured with a single shot pepper-pot device are described. First results of mathematical evaluation from the commissioning of the new GSI pre-stripper linac structures are presented.  
 
PT10 Emittance and dispersion measurements at TTF quadrupole, dipole, linac, acceleration 180
 
  • M. Castellano, A. Cianchi, V.A. Verzilov
    INFN-LNF, Laboratori Nazionali di Frascati dell'INFN, Frascati, Italy
  It is well known that beam dispersion , along with the Twiss parameters and emittance, contributes to the beam spot size. So that, in general, anomalous dispersion is an undesirable event and must be minimized by careful tuning the machine. If not, when the spot size is used to infer beam emittances, as it is the case of the "quadrupole scan" method, basically employed at TTF, the unknown dispersion can lead to overestimated values for the emittance. This paper presents the first attempt to determine the dispersion function at several points of the TTF Linac and to separate its contribution to the local emittance measurement, performed by means of the OTR imaging technique.  
 
PT16 Status of the delta synchrotron light-monitoring-system synchrotron, radiation, synchrotron-radiation, shielding 196
 
  • U. Berges, K. Wille
    DELTA, Institute for Accelerator Physics and Synchrotron Radiation, University of Dortmund, Germany
  A synchrotron radiation source like DELTA needs an optical monitoring system to measure the beam size at different points of the ring with high resolution and accuracy. The measurements with the present synchrotron light monitors show that beam sizes larger than 250 μm can be measured. The measured emittance is of the order of the theoretical values of the optics and goes down to 8 nm rad. The magnification of the system can simply be increased by adding another lens to measure smaller emittances and beamsizes down to 100 μm. In this case you still have an optical image of the beam available, but sometimes the position of the camera has to be adapted due to the great magnification of the optical system. The image processing system which is based on a VME Framegrabber makes a two dimensional gaussian fit to the images from different synchrotron light-monitors. First tests with monochromatic components of the synchrotron radiation (500 nm and 550 nm) and with short time cameras (shutter time down to 1/10000 s) have been performed. A two-dimensional PSD has been installed to measure slow beam motion. To measure small beam sizes, especially in the vertical plane, diffraction elements will be used. This paper gives an overview over the present installation and the results.