Impact of the positive ion current on large size neutrino detectors and delayed photon emission

TL;DR

This paper investigates how positive ion currents in large liquid argon neutrino detectors cause charge signal quenching and delayed photon emission, raising concerns for surface-operated multi-ton experiments.

Contribution

It provides the first detailed analysis of ion-induced effects on charge and photon signals in large liquid argon detectors for neutrino physics.

Findings

Ion currents cause charge signal quenching.

Ion recombination leads to delayed photon emission.

Potential issues for surface-based large detectors.

Abstract

Given their small mobility coefficient in liquid argon with respect to the electrons, the ions spend a considerably longer time in the active volume. We studied the effects of the positive ion current in a liquid argon time projection chamber, in the context of massive argon experiments for neutrino physics. The constant recombination between free ions and electrons produces a quenching of the charge signal and a constant emission of photons, uncorrelated in time and space to the physical interactions. The predictions evidence some potential concerns for multi-ton argon detectors, particularly when operated on surface