Study of a Threshold Cherenkov Counter Based on Silica Aerogels with Low Refractive Indices

TL;DR

This paper reports on the development and testing of a threshold Cherenkov counter using low-refractive-index silica aerogels for effective pion/kaon separation in the 1.0 to 2.5 GeV/c momentum range.

Contribution

It introduces a new technique for producing low-refractive-index silica aerogels and demonstrates their application in a Cherenkov counter for particle identification.

Findings

Aerogels with a refractive index of 1.013 were successfully produced.

The Cherenkov counter achieved over 90% efficiency for π/K separation.

The aerogels maintained sufficient transparency despite low refractive index.

Abstract

To identify $\pi^{\pm}$ and $K^{\pm}$ in the region of $1.0\sim 2.5$ GeV/c, a threshold Cherenkov counter equipped with silica aerogels has been investigated. Silica aerogels with a low refractive index of 1.013 have been successfully produced using a new technique. By making use of these aerogels as radiators, we have constructed a Cherenkov counter and have checked its properties in a test beam. The obtained results have demonstrated that our aerogel was transparent enough to make up for loss of the Cherenkov photon yield due to a low refractive index. Various configurations for the photon collection system and some types of photomultipliers, such as the fine-mesh type, for a read out were also tested. From these studies, our design of a Cherenkov counter dedicated to $\pi / K$ separation up to a few GeV/c %in the momentum range of $1.0 \sim 2.5$ GeV/c with an efficiency greater than $90$ \% was considered.