Author: Satoh, M.
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MOPF28 Beam Diagnostics and Timing Monitoring for SuperKEKB Injector Linac 110
 
  • F. Miyahara, K. Furukawa, R. Ichimiya, N. Iida, M. Ikeno, H. Kaji, M. Satoh, M. Shoji, T. Suwada, M. Tanaka, Y. Yano
    KEK, Ibaraki, Japan
  • T. Okazaki
    EJIT, Hitachi, Ibaraki, Japan
 
  The SuperKEKB injector linac has multiple operation modes for the electron beam injection into 3 separate rings, SuperKEKB HER, PF (Photon Factory) Ring and PF-AR, and the positron beam injection into the damping ring and the SuperKEKB LER. The operation modes can be switched every 20 milli-second with arbitrary order. The beam parameters such as charge, energy and emittance are different for each of the rings. Moreover, the bunch charge of the electron beam, 5nC, is 5 times higher and the emittance of ~10 mm•mrad is 30 times lower than those of the KEKB injector. Thus, development of BPM readout system with a wide dynamic range and installation of optical fiber detector with a good S/N ratio for the wire scanners and bunch-length monitor have been performed. For stable operation of the linac, many timing signals have to be monitored as well. To that end we have developed 32-bit multi-hit time-to-digital converters (TDCs) with 1-ns resolution. The first beam tests of those systems are reported in this paper.  
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WEPD04 High Position Resolution and High Dynamic Range Stripline Beam Position Monitor (BPM) Readout System for the KEKB Injector Linac Towards the SuperKEKB 637
 
  • R. Ichimiya, K. Furukawa, F. Miyahara, M. Satoh, T. Suwada
    KEK, Ibaraki, Japan
 
  The SuperKEKB accelerator is now being upgraded to bring the world highest luminosity (L=8x1035/cm2/s). Hence, the KEKB injector linac has to produce low emittance and high charge electron (20 mm mrad, 7 GeV/c2, 5 nC) and positron (20 mm mrad, 4 GeV/c2, 4 nC) beam, respectively. In order to achieve these criteria, the accelerator structure has to be aligned within 0.1 mm position error. Since BPMs are essential instruments for beam based alignment (BBA), it is required to have one magnitude better position resolution to get enough alignment results. We have begun to develop high position resolution BPM readout system with narrow bandpass filters (fc = 180 MHz) and 250 MSa/s 16-bit ADCs. It handles two bunches with 96 ns interval separately and has a dynamic range from 0.1 nC to 10 nC. To compensate circuit drift, two calibration (x-direction and y-direction) pulses are output to the BPM electrodes between beam cycles (20 ms). Since it needs to achieve not only high position resolution but also good position accuracy, overall non-linearity within ±0.02 dB is required and the system has to have more than ±5 mm accurate position range. We confirmed the system performance with a 3-BPM resolution tests at KEK Injector Linac and it turned out that the system has 3 μm position resolution. We plan to install this system during 2015 summer shutdown.  
poster icon Poster WEPD04 [0.828 MB]  
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