Time and band-resolved scintillation in time projection chambers based on gaseous xenon

TL;DR

This study systematically investigates the time and wavelength-dependent scintillation properties of xenon-based TPCs under various conditions, providing insights into emission mechanisms and optimizing detector performance.

Contribution

It offers new detailed measurements of scintillation time constants and yields across different pressures, fields, and wavelengths, including exploration of non-conventional emission mechanisms.

Findings

Time constants vary with electric field and pressure.

Identification of non-conventional scintillation mechanisms.

Quantitative data on scintillation yields for different conditions.

Abstract

We present a systematic study of the time and band-resolved scintillation in xenon-based time projection chambers (TPCs), performed simultaneously for the primary (S1) and secondary (S2) components in a small, purity-controlled, setup. We explore a range of conditions of general academic interest, focusing on those of relevance to contemporary TPCs: pressure range ([1- 10] bar), pressure-reduced electric fields ([0-100] V/cm/bar in the drift region (S1) and up to the proportional scintillation regime in the multiplication region (S2)), wavelength-band ([145-250], [250-400], [400-600] nm), and primary excitation ($\alpha$, $\beta$-particles). Attention is paid to the possibility of non-conventional scintillation mechanisms such as the 3rd continuum emission, recombination light from $\beta$-electrons at high pressure (for S1), emission from high-lying excited states and neutral bremsstrahlung (for S2). Time constants and, specially, scintillation yields have been obtained as a function of electric field and pressure, the latter aided by Geant4 simulations.