TESTS OF THE POSITION SENSITIVITY OF AN IMPROVED PASS DETECTOR

We report our progress in the development of the planar array of super heated superconductors (PASS) grain detector. We have fabricated array s containing 250 x 250 tin grains of radius as small as 2 mum and have measured their response to low energy gamma-radiation. Grains with ra dius 2.5 mum are estimated to give an energy sensitivity of about 1 ke V at temperature T approximately 2 K. Calculations based on the global heating model agree very well with the results of these radiation tes ts. Detailed calculations have been performed of the position sensitiv ity of the detector in the multilayer configuration with three SQUID p ick-up coils and we conclude that three dimensional 300 mum resolution can presently be realized with a detector of volume 1 cm3. Measuremen ts using a single pick-up coil on a line of 200 indium grains with 12 mum radius agree with the calculated response. We also tested the resp onse of a stack of three arrays and observed no increase in the spread of transition temperatures which is a very encouraging result regardi ng a future multilayer detector.