Large area PPAC development at the Rare Isotope Science Project

Large area position sensitive parallel plate avalanche counters (PPACs) have been fabricated for the Rare Isotope Science Project. These detectors have active areas of 20 × 20 cm² and 40 × 20 cm², and utilize a stripped electrode structure, together with a delay-line readout, to extract position information. The 20 × 20 cm² detector performance was tested with 3 MeV/u ¹²C and ¹⁶O beams. A position resolution better than 1 mm, full width at half maximum, and a detection efficiency of 94% were measured with an incident beam intensity of 2 × 10⁶ particles per second. A new production technique, using photolithography, that makes the fabrication of stripped PPAC electrodes larger in area than was previously possible, is also presented.