Results from the Slac Psc Development Program

Planar Spark Counters (PSC's) have unique detection properties for charged particles. These counters have achieved the best time resolutions of any particle detector.' This in combination with their other properties makes PSC's attractive for use in high energy particle physics. At SLAC a program to develop this technology has been in progress since 1978.2 Last year we tested a pair of PSC's at the PEP storage ring and I will report on the results here.3 Provided that one can extend the PSC technology to large devices, PSC systems could have time resolutions of 50 psec or better. In Fig. 1 I have plotted the momentum for 50 and 100 psec time-of-flight particle separation over a 1.7 m flight path for various pairs of particle. It is seen from this figure that such a system would make good inroads on the difficult l-2 GeV momentum region. PSC systems will have a granularity dictated by the cost of electronics channels: at least an order of magnitude over conventional scintillation counter systems is not unreasonable, e.g., a cylindrical array of 1,000 PSC strip lines compared to one hundred or so scintillation counters. This feature will reduce ambiguities arising from more than one particle striking a single detector element.