Test of a small prototype of the COMET cylindrical drift chamber

TL;DR

This study evaluates a small cylindrical drift chamber prototype for the COMET experiment, demonstrating high spatial resolution and efficiency with specific gas and voltage conditions, confirming its suitability for the full detector.

Contribution

It provides experimental validation of a prototype CDC design and gas mixture, supporting its implementation in the COMET Phase-I experiment.

Findings

Spatial resolution of 150 μm achieved

Hit efficiency of 99% demonstrated

Optimal operation above 1800 V

Abstract

The performance of a small prototype of a cylindrical drift chamber (CDC) used in the COMET Phase-I experiment was studied by using an electron beam. The prototype chamber was constructed with alternating all-stereo wire configuration and operated with the He-iC$_{4}$H$_{10}$ (90/10) gas mixture without a magnetic field. The drift space-time relation, drift velocity, d$E$/d$x$ resolution, hit efficiency, and spatial resolution as a function of distance from the wire were investigated. The average spatial resolution of 150 $\mu$m with the hit efficiency of 99% was obtained at applied voltages higher than 1800 V. We have demonstrated that the design and gas mixture of the prototype match the operation of the COMET CDC.