| Irfu-10-107
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| High resolution photon timing with MCP-PMTs: a comparison of commercial constant fraction discriminator (CFD) with ASIC-based waveform digitizers TARGET and WaveCatcher. |
| D. Breton, E. Delagnes, J. Maalmi, K. Nishimura, L.L. Ruckman, G. Varner, J. Va’vra |
| There is considerable interest to develop new time-of-flight detectors using, for example, micro-channel-plate photomultiplier tubes (MCP-PMTs). The question we pose in this paper is if available waveform digitizer ASICs, such as the
WaveCatcher and TARGET, operating with a sampling rate of 2-3 GSa/s can compete with 1GHz BW CFD/TDC/ADC electronics. We have performed a series of measurements with these waveform digitizers coupled to MCP-PMTs operating at low gain and with a signal equivalent to ~40 photoelectrons. The tests were done with a laser diode on detectors operating under the same
condition as used previously in SLAC and Fermilab beam tests. Our measurement results indicate that one can achieve similar resolution with both methods. Although commercial CFD-based
electronics are readily available and perform very well, they are impractical to implement on a very large scale, necessitating custom electronics. In addition, analog delay line requirements make it very difficult to incorporate CFD discriminators in ASIC
designs. |
