Testmessungen an einem Photondetektor Prototyp fuer den RICH von HERA-B

A photondetector was studied with respect to its usefullness for the RICH of HERA-B, a new B-physics experiment at DESY, Hamburg. The detector consists of an array of single-wire proportional chambers wich were made photosensitive in the UV-region by adding Tetrakis-(dimethylamino)-ethylen (TMAE) to the chamber gas. Tests with a small RICH with an argon radiator at an electron test beam at DESY could be performed. The number of seen Cerenkov photons was about 30% less than had been expected from the TMAE quantum efficiency given by Holroyd et al. Extrapolation to the HERA-B RICH results in 20 to 30 photons for a #beta# #approx =# 1 particle. The time distribution was narrow enough to distinguish different events at a rate of 1/96 ns. In the testbeam experiment appeared a background, that could not be explained, but it was most likely caused by the test RICH and not by the detector. (orig.)Available from FIZ Karlsruhe / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman