Eur. Phys. J. Special Topics 162, 251-257 (2008)
https://doi.org/10.1140/epjst/e2008-00800-2

The COMPASS RICH-1 detector upgrade

¹ CEA Saclay, DSM/DAPNIA, Gif-sur-Yvette, France
² INFN, Sezione di Torino and University of Torino, Torino, Italy
³ Technische Universität München, Physik Department, Garching, Germany
⁴ INFN, Sezione di Trieste and University of Trieste, Trieste, Italy
⁵ LIP, Lisbon, Portugal
⁶ INFN, Sezione di Torino and University of East Piemonte, Alessandria, Italy
⁷ Universität Erlangen-Nürnberg, Physikalisches Institut, Erlangen, Germany
⁸ Charles University, Prague, Czech Republic and JINR, Dubna, Russia
⁹ Universität Freiburg, Physikalisches Institut, Freiburg, Germany
¹⁰ Universität Mainz, Institut für Kernphysik, Mainz, Germany
¹¹ Universität Bonn, Helmholtz-Institut für Strahlen- und Kernphysik, Bonn, Germany
¹² CERN, European Organization for Nuclear Research, Geneva, Switzerland
¹³ Technical University of Liberec, Liberec, Czech Republic

Corresponding author: Frank.Nerling@cern.ch

Abstract

The COMPASS experiment at CERN provides hadron identification in a wide momentum range employing a large size gaseous Ring Imaging CHerenkov detector (RICH). The presence of large uncorrelated background in the COMPASS environment was limiting the efficiency of COMPASS RICH-1 in the very forward regime. A major upgrade of RICH-1 required a new technique for Cherenkov photon detection at count rates of several per channel in the central detector part, and a read-out system allowing for trigger rates of up to 100 kHz. To cope with these requirements, the photon detectors of the central region have been replaced with a fast photon detection system described here, while, in the peripheral regions, the existing multi-wire proportional chambers with CsI photo-cathodes have been equipped with a new read-out system based on APV preamplifiers and flash ADC chips. The new system consists of multi-anode photo-multiplier tubes (MAPMTs) coupled to individual fused silica lens telescopes, and fast read-out electronics based on the MAD4 amplifier-discriminator and the dead-time free F1 TDC chip. The project was completely designed and implemented in less than two years: The upgraded detector is in operation since the 2006 CERN SPS run. We present the photon detection design, constructive aspects and test studies to characterise the single photon response of the MAPMTs coupled to the read-out system as well as the detector performance based on the 2006 data.