Improved Time Response in Scintillation Counting

Antiproton observations at the Bevatron are typical of scintillation counting experiments that would benefit by improved time response. The antiproton yield increases as the flight path of the particle is shortened and the corresponding solid angle increased. From the electronics standpoint, the problem of pulse rise time prevents an arbitrary reduction of the flight path. The first limitation appears in the scintillator-photomultiplier combination, the second in the interconnecting cable, and the last in the indicating circuitry, i.e., coincidence devices, scalers, oscilloscopes, amplifiers, etc. In Part I of this paper, transit time data for the RCA type 6810 are presented. These suggest a method for improving tube performance. Figures are given in Part II for pulse distortion in typical coaxial cables. Performance data are given for a low-distortion 125-ohm transmission line. The line, using styrofoam dielectric, is easily made and useful over several hundred feet in the 10-10 second range.