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single bunch

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PT02 Pill-Box Cavity BPM For TESLA Cryomodul diagnostics, linac, monitoring, position, resonance 172
 
  • V. Sargsyan
    TU-Berlin, Technische Universität, Berlin, Germany
  A new cavity BPM with 10 μm resolution is designed and fabricated to perform single bunch measurements at the TESLA linear collider. In order to have a low energy dissipation in the cryogenic supermodule, the inner surface of the cavity is copper plated. Cross-talk is minimised by a special polarisation design. The electronics, at 1.5 GHz, is a homodyne receiver normalised to the bunch charge. Its LO-signal for down-conversion is taken from the same cavity.  
 
PT17 Impedance-Matching-Transformer for Capacitive Pick-Ups BPM, diagnostics, longitudinal transfer function, impedance matching transformer, capacitive pick-up, SIS 208
 
  • J. Schölles, W. Kaufmann
    GSI, Gesellschaft für Schwerionenforschung, Darmstadt, Germany
  The transfer line from the GSI heavy ion synchrotron (SIS) to the experimental set ups is equipped with segmented capacitive pick-ups for beam position measurement. This beam position measurement will be designed to cover a dynamic range of 160 dB and single-bunch evaluation. For taking measurements with maximum sensitivity the best choice is a high-impedance tap at the pick-up referring to the bunch length of 50...500 ns. Therefore the feeding of 50 Ω coax-cables will be realized by an impedance-matching-transformer located close to the pick-up. It has an impedance >10 kΩ at the primary side and 50 Ω matching at the secondary side with a foreseen bandwidth of 200 MHz. So it is possible to use low noise amplifiers with 50 Ω input in a radiation-safe environment without loading the pick-up with 50 Ω. A specialized impedance-matching-transformer is now under development and the result will be presented.  
 
PT21 Microwave measurement of intra bunch charge distributions diagnostics, instrumentation 219
 
  • M. Dehler
    PSI, Paul Scherrer Institut, Villigen, Switzerland
  A direct way of obtaining intra bunch charge distributions is to measure the amplitude roll off as well as the phase behavior of the spectrum of the single bunch self field. To that effect, a microwave pickup together with a microwave front end has been installed in the storage ring of the Swiss Light Source (SLS). As pickup, button type bpms are used, which have been designed for a broad band behavior in the excess of 30 GHz. Three bpms together with their individual front ends are used in order to sample the beam spectrum at frequencies of 6, 12 and 18 GHz, which compares to the standard spectrum of a 1 mA single bunch extending to approximately 12 GHz (13 ps rms bunch length). The signals are mixed to base band in loco using the multiplied RF frequency as a LO. By shifting the LO phase, simultaneously the amplitude roll off as well the complex phase of the beam spectrum can be obtained. Where using a resonator as a pickup would smear out the response over several bunches, allowing only the determination of average values, the current setup has a band width of approximately 2 GHz, so that individual bunches in the 500 MHz bunch train can easily be resolved.