# Triplet Lifetime in Gaseous Argon

## TL;DR

This paper reports the measurement of the longest triplet lifetime in gaseous argon, demonstrating ultra-pure conditions in a dark matter experiment, and investigates scintillation light quenching effects.

## Contribution

It provides the first precise measurement of the gaseous argon triplet lifetime during cooling, indicating ultra-pure argon and exploring scintillation quenching effects.

## Key findings

- Triplet lifetime of 3.480 μs measured, the longest reported.
- Impurities are effectively monitored via scintillation light.
- Quenching effects on scintillation components are analyzed.

## Abstract

MiniCLEAN is a single-phase liquid argon dark matter experiment. During the initial cooling phase, impurities within the cold gas ($<$140 K) were monitored by measuring the scintillation light triplet lifetime, and ultimately a triplet lifetime of 3.480 $\pm$ 0.001 (stat.) $\pm$ 0.064 (sys.) $\mu$s was obtained, indicating ultra-pure argon. This is the longest argon triplet time constant ever reported. The effect of quenching of separate components of the scintillation light is also investigated.