Long term experience and performance of COMPASS RICH-1

Abstract

JINST 9 C09011ABSTRACT: COMPASS RICH-1 is a large size gaseous Imaging Cherenkov Detector providing hadron identification in the range from 3 to 55 GeV/c, in the wide acceptance spectrometer of the COMPASS Experiment at CERN SPS.It uses a 3 m long C 4 F 10 radiator, a 21 m 2 large VUV mirror surface and two kinds of photon detectors: MAPMTs and MWPCs with CsI photocathodes, covering a total of 5.5 m 2 . It is in operation since 2002 and its performance increased thanks to progressive optimization and to a major upgrade of its photon detection system, implemented in 2006; a new upgrade is foreseen for 2016, with the use of MPGD-based photon detectors.The main characteristics of COMPASS RICH-1 components are described and the most critical aspects related to the C 4 F 10 radiator gas system, to the mirrors and their alignment, as well as the performance of the photon detectors are presented and discussed. The response of the MWPCs and the observed evolution of the effective quantum efficiency of the CsI photocathodes is analyzed. The properties and performance of the MAPMTs with individual fused lens telescopes are presented together with the readout characteristics. The PID performance of COMPASS RICH-1 is discussed and the future upgrade program is mentioned.

STCF conceptual design report (Volume 1): Physics & detector

“…The background simulation (Section 3.2.3) indicates that the first (innermost) layer of the MDC is subjected to the highest background count rate, approximately 200 to 400 kHz, leading to severe interference in the measurement of charged tracks from signal events. The GARFIELD [428] simulation demonstrates that the signal in each cell lasts for 200 to 500 ns due to the electrons distributed by the uncertainty of the distance from the particle track to the wire. As a consequence, the readout electronics must have a fast shaping time, and sufficient background shielding in the MDC endcap is necessary.…”

Evolution and recent developments of the gaseous photon detectors technologies

“…RD26-type MWPC-based PDs have been [31] and still are successfully used by several experiments: NA44 [32] at CERN, HADES [33] at GSI, COMPASS [34] at CERN (5.5 m 2 active area), STAR [35] at RHIC, HALL-A [36] at JLAB, ALICE [37] at CERN (10 m 2 active area), etc. The impact of MWPCbased PDs on the physics results of the experiments is very relevant and they can be considered the classical successful gaseous PDs.…”