Measurement of emission spectrum for gaseous argon electroluminescence in visible light region from 300 to 600 nm

TL;DR

This study measures the visible light emission spectrum of gaseous argon electroluminescence in the 300-600 nm range, exploring the underlying mechanisms including the traditional EL and the new neutral bremsstrahlung model.

Contribution

It provides the first detailed spectral measurements of argon electroluminescence in the visible range and compares the data with existing models, considering impurity effects.

Findings

Detected visible light components in argon electroluminescence

Spectral data supports the neutral bremsstrahlung model over traditional EL mechanisms

Impurity effects, especially nitrogen, influence the emission spectrum

Abstract

A double-phase Ar detector can efficiently identify particles and reconstruct their positions. However, the properties of electroluminescence (EL) for secondary light emission in the gas phase are not fully understood. Earlier studies have explained the EL process using an ordinary EL mechanism because of an Ar excimer; however, this mechanism does not predict the emission of visible light (VL). Recent measurements have demonstrated VL components in Ar gas EL, to explain which a new mechanism called neutral bremsstrahlung (NBrS) was proposed. In this study, we investigated gaseous Ar EL in the VL region from 300 to 600 nm at room temperature and normal pressure using a gaseous time projection chamber (TPC). The secondary emission light from the TPC luminescence region was dispersed using a spectrometer. The observed spectrum was interpreted using the ordinary EL and NBrS models, and the effect of nitrogen impurities is discussed herein.