The HERA-B Ring Imaging Cherenkov Counter

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.Comment: 29 pages, 23 figure

The physics potential of the HERA-B RICH

The physics potential of the RICH counter of the HERA-B experiment is illustrated in several MC simulated examples. In particular, we discuss its performance as an auxiliary tracking device.http://www.sciencedirect.com/science/article/B6TJM-3X64HB7-1S/1/d55375c0b74a9059447bb2d147fe2f1

J/ψ production via χc decays in 920 GeV pA interactions [J-\psi Production via \chi_c Decays in 920 GeV pA Interactions]

Using data collected by the HERA-B experiment, we have measured the fraction of J/ψ's produced via radiative χc decays in interactions of 920 GeV protons with carbon and titanium targets. We obtained Rχc= 0.32±0.06_stat±0.04_sys for the fraction of J/ψ from χc decays averaged over proton–carbon and proton–titanium collisions. This result is in agreement with previous measurements and is compared with theoretical predictions

Measurement of D0D^0, D+D^+, Ds+D_s^+ and D∗+D^{*+} Production in Fixed Target 920-GeV Proton-Nucleus Collisions.

The inclusive production cross sections of the charmed mesons D^0, D^+, D_s^+ and D^{*+} have been measured in interactions of 920 GeV protons on C, Ti, and W targets with the HERA-B detector at the HERA storage ring. Differential cross sections as a function of transverse momentum and Feynman's x variable are given for the central rapidity region and for transverse momenta up to \pT=3.5 GeV/$c$. The atomic mass number dependence and the leading to non-leading particle production asymmetries are presented as well.Comment: Submitted to EPJ