Speaker
Description
Test beams are frequently used for developing high resolution Time-of-Flight (ToF) equipment. To investigate the timing properties of detectors under test, a reliable and reproducible time reference counter (TRC) would be an important asset for a test beam facility. Frequently ToF detectors are calibrated only occasionally and it may be difficult to guarantee that their calibration is maintained for the whole period of measurement. On the other side using a distinct “time reference counter” to characterize the time resolution of the timing detector under test, would provide the ability of permanently monitoring the calibration of the reference counter itself. To achieve this goal we have assembled a scheme with 3 timing counters based on Cherenkov radiation from quartz bars and a quartz block readout with MCP-PMT photodetectors, which insure excellent timing properties. By combining the 3 time measurements it is possible to extract the resolution (better than 10 ps) of the TRC counter (with quartz block), and use it as reference for any other device installed on the beam. This method has been tested at CERN (H8 beam in SPS North Hall) and in an electron beam at DESY, where the TRC was used as permanently calibrated time reference system, to study other types of timing detectors. To ensure the high quality of the time measurement based on this system, we have investigated the behaviour of the 3 counters with Monte Carlo simulations, and experimentally, demonstrating the possibility of using the redundancy of the measurements to keep under control also the potential correlations between the time measurements of the 3 counters. Typical configurations for this TRC system are discussed.
