LNL的反沖質量譜儀的新型焦面探測器－PS-PPAC

Two kinds of new focal pane detector have been developed for study of reactions induced by heavy ions with the recoil mass spectrometer (RMS) at Legnaro National laboratory, Italy. They are the Padova and Argonne types of two dimensional position sensitive-parallel plate avalanche counters (PSPPAC) with active area of 70mm×140mm. The special attention is paid to minimizing the volume of detector. In the construction of the PPAC's quite compact integral delay-lines from which position signals are extracted, and correspondingly the quite small discrete LC elements are used. The test method of their performances are described and the characteristics are presented. For the test of 241Am-αsource, the position resolution for X and Y of Padova PPAC is 1.0mm and 0.8mm, and 1.8mm and 1.0mm for Argonne PPAC, respectively. The detection efficiency is 49% and 85% for Padova PPAC and 12.75% and 4.5% for Argonne PPAC, respectively. The position resolution, especially the detection efficiency, for any detectors when the heavy ions are detected are certainly improved.