A novel liquid argon purity monitor based on 207 Bi

TL;DR

This paper introduces a new liquid argon purity monitor utilizing a 207 Bi radioactive source, enabling precise, rapid, and continuous impurity measurements in liquid argon TPC experiments with minimal interference.

Contribution

The paper presents a novel purity monitor based on 207 Bi, capable of continuous, accurate impurity assessment without disrupting detector operations, and demonstrates successful prototype operation.

Findings

Successful prototype operation in test stands

High measurement precision and speed

Ability to assess a wide range of purities

Abstract

A novel liquid argon purity monitor based on a 207 Bi radioactive source, emitting monochromatic internal-conversion electrons, is presented. This new monitor allows for a very precise and fast measurement of the electronegative impurities concentration in liquid argon. It can be operated continuously in liquid argon TPC experiments without interfering with the main detector operation. Different drift lengths can be assembled for the proposed device, to assess a large range of liquid argon purities while minimizing systematic uncertainties. Two prototypes have been built and successfully operated in dedicated test stands. The results and performance are reported.