Attenuation measurements of vacuum ultraviolet light in liquid argon revisited

TL;DR

This study revisits the attenuation of vacuum ultraviolet light in liquid argon, addressing previous measurement issues and establishing that pure liquid argon is highly transparent down to 118 nm with an estimated attenuation length of at least 1.10 meters.

Contribution

It provides refined, systematic measurements of VUV light attenuation in liquid argon, improving accuracy and addressing prior technical uncertainties.

Findings

Liquid argon is fully transparent down to 118 nm.

No xenon-related absorption effects observed.

Attenuation length estimated to be at least 1.10 meters.

Abstract

The attenuation of vacuum ultraviolet light in liquid argon in the context of its application in large liquid noble gas detectors has been studied. Compared to a previous publication several technical issues concerning transmission measurements in general are addressed and several systematic effects were quantitatively measured. Wavelength-resolved transmission measurements have been performed from the vacuum ultraviolet to the near-infrared region. On the current level of sensitivity with a length of the optical path of 11.6 cm, no xenon-related absorption effects could be observed, and pure liquid argon is fully transparent down to the short wavelength cut-off of the experimental setup at 118 nm. A lower limit for the attenuation length of pure liquid argon for its own scintillation light has been estimated to be 1.10 m based on a very conservative approach.