Development of chemically-milled gridded avalanche counters for use in a time-of-flight telescope

Abstract

Small area chemically-milled parallel-grid avalanche counters (PGAC) with isobutane counter gas and thin entrance and exit windows, have been developed as transmission timing detectors for use in heavy-ion experiments. The performance of the counters has been investigated with α particles and elastically scattered 35Cl ions. To optimize the PGAC capabilities it is best to operate at pressures greater than 14 Torr where good timing and efficiency are available well below the breakdown threshold. A system timing resolution, using a silicon surface barrier stop detector, of 360 ps was achieved.