부산대학교 도서관

Tests of 2300 Hamamatsu multianode photomultipliers (1543 pieces of R5900-M16 and 762 pieces of R5900-M4) have been tested on the bench in order to evaluate their performance for use as position-sensitive photon detectors in the ring imaging Cherenkov counter of the HERA-B experiment.1The groups responsible for the HERA-B RICH comprise: University of Texas at Austin, University of Barcelona, University of Coimbra, Portugal, Northwestern University, University of Houston, J. Stefan Institute and University of Ljubljana, Slovenia, with support from DESY and the University of Hamburg.1A weak and stable source of photons has been obtained by Cherenkov radiation of electrons from a 90Srsource in a quartz radiator. From measurements of the count rate versus high voltage, optimal high-voltage values have been obtained as well as a parameter (RQE) corresponding to the relative quantum efficiency. Distributions of the number of photomultipliers as a function of the optimal high voltage and as a function of the relative quantum efficiency are presented. The measured parameters are in good correlation with those provided by the manufacturer. The stability of the photomultipliers has also been followed over two years. The observed count rate decrease is consistent with the radioactive decay of 90Sr.