The HERA-B Ring Imaging Cherenkov Counter

TL;DR

The HERA-B RICH detector employs a 2.8 m C_4F_10 gas radiator and a large spherical mirror to accurately image Cherenkov rings, achieving high photon detection efficiency and stable performance since 1999.

Contribution

This paper presents the design, construction, and performance validation of the HERA-B RICH detector, demonstrating its effective photon detection and resolution capabilities.

Findings

Detected photons per beta=1 particle: 33

Single hit resolution: 0.7 mrad (fine), 1 mrad (coarse)

Stable and reliable operation since 1999

Abstract

The HERA-B RICH uses a radiation path length of 2.8 m in C_4F_10 gas and a large 24 square meters spherical mirror for imaging Cherenkov rings. The photon detector consists of 2240 Hamamatsu multi-anode photomultipliers with about 27000 channels. A 2:1 reducing two-lens telescope in front of each PMT increases the sensitive area at the expense of increased pixel size, resulting in a contribution to the resolution which roughly matches that of dispersion. The counter was completed in January of 1999, and its performance has been steady and reliable over the years it has been in operation. The design performance of the RICH was fully reached: the average number of detected photons in the RICH for a beta=1 particle was found to be 33 with a single hit resolution of 0.7 mrad and 1 mrad in the fine and coarse granularity regions, respectively.