The Ring Imaging Cherenkov detector (RICH) of the AMS experiment

TL;DR

This paper reports on the development and testing of a RICH detector prototype for the AMS experiment, demonstrating its ability to measure charge and velocity of cosmic particles with high precision.

Contribution

The paper presents the design, construction, and performance evaluation of a RICH detector prototype for cosmic ray measurements on the ISS.

Findings

Charge separation up to Fe achieved

Velocity resolution around 0.1% for singly charged particles

Successful detection of Cherenkov rings for various nuclei

Abstract

The Alpha Magnetic Spectrometer (AMS) experiment to be installed on the International Space Station (ISS) will be equipped with a proximity focusing Ring Imaging Cherenkov (RICH) detector for measuring the electric charge and velocity of the charged cosmic particles. A RICH prototype consisting of 96 photomultiplier units, including a piece of the conical reflector, was built and its performance evaluated with ion beam data. Preliminary results of the in-beam tests performed with ion fragments resulting from collisions of a 158 GeV/c/nuc primary beam of Indium ions (CERN SPS) on a Pb target are reported. The collected data included tests to the final front-end electronics and to different aerogel radiators. Cherenkov rings for a large range of charged nuclei and with reflected photons were observed. The data analysis confirms the design goals. Charge separation up to Fe and velocity resolution of the order of 0.1% for singly charged particles are obtained.