Design and construction of a Cherenkov imager for charge measurement of nuclear cosmic rays

TL;DR

The paper presents the design and construction of CHERCAM, a Cherenkov imager for measuring nuclear cosmic ray charges, highlighting its technical features and expected performance for balloon-based experiments.

Contribution

It introduces a novel Cherenkov imager with specific design features enabling charge measurement of cosmic rays in high-altitude conditions.

Findings

Achieves charge separation for Z 1-26

Proportional Cherenkov light yield to particle charge squared

Designed for safe operation in high-altitude environments

Abstract

A proximity focusing Cherenkov imager called CHERCAM, has been built for the charge measurement of nuclear cosmic rays with the CREAM instrument. It consists of a silica aerogel radiator plane across from a detector plane equipped with 1,600 1" diameter photomultipliers. The two planes are separated by a ring expansion gap. The Cherenkov light yield is proportional to the charge squared of the incident particle. The expected relative light collection accuracy is in the few percents range. It leads to an expected single element separation over the range of nuclear charge Z of main interest 1 < Z < 26. CHERCAM is designed to fly with the CREAM balloon experiment. The design of the instrument and the implemented technical solutions allowing its safe operation in high altitude conditions (radiations, low pressure, cold) are presented.