Fabrication and performance evaluation of parallel plate avalanche counters for RISP

Abstract

We have fabricated and tested position-sensitive parallel plate avalanche counters (PPACs) for the Rare Isotope Science Project in Korea. These detectors have active areas of 10 cm x 10 cm with a stripped electrode structure. A delay line readout was employed to obtain the position information. Detector performance was tested with an Am-241 alpha source. The detection efficiency, position, and time resolutions were studied with C3F8 gas pressures from 4 to 28 Torr and high voltages from 650 to 1100 V. Detection efficiency was greater than 99%. The position and time resolutions were measured to be 380 mu m and 520 ps of full-width at half maximum (FWHM), respectively.