A TMAE based photon detector for the HERA-B RICH

In the framework of the recently approved HERA-B experiment at DESY, a photon detector based on TMAE is investigated for a possible later use in the HERA-B RICH detector. To avoid condensation of TMAE, the partial pressure of TMAE is kept as low as possible. The lower absorption is compensated by a longer absorption path in the chamber. The chamber is made up of rectangular cells, 10 cm long with a 0.8 × 0.8 cm2 base. The results are presented of test beam studies that have been carried out since spring 1994 with a 32 × 32 channel prototype chamber in a setup at the DESY test beam facility.