Test of a new prototype of multiwire proportional chamber with pixel pad cathode readout

Le résumé fourni par la source

A new prototype of multiwire proportional chamber (MWPC) with pixel configurated pad cathode was built as a joint effort by McGill University, Lund University and Oak Ridge National Laboratory as part of the development of the tracking system of the PHENIX detector at the Relativistic Heavy Ion Collider (RHIC). This thesis first describes the implementation of a new readout electronics for the pad chambers. In this electronics, the charge of the pads is digitized using a preamplifier/shaper/discriminator integrated CMOS chip with adjustable threshold. All chips and components are mounted on specially designed 48-channel readout cards using chip-on-board (COB) technology. Using this new readout, the performance of the pad chamber is tested with cosmic rays and X-ray source. The prototype response, efficiency and gain are measured as functions of detector operating conditions. The operation of the chamber shows a very good stability over long periods of testing. Excellent efficiencies, above 99%, are observed in tests using discriminator thresholds between 2--4 fC, which represents 1--1.5% of the most probable anode charge produced at a normal anode voltage of 1850V. Under this conditions, the reconstructed hit patterns are relatively small. This is leading to a very good position resolution of about half of the cell size. An excellent description of chamber behavior was obtained using Monte Carlo simulations. showing that we can use these simulations to predict and optimize the performance of such chamber.

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