On Proportional Scintillation in Very Large LXe Detectors

TL;DR

This paper reevaluates the use of proportional scintillation in liquid xenon detectors, demonstrating that with proper geometry, it is a viable technique for large-scale dark matter detectors, overcoming past technical challenges.

Contribution

The study clarifies that geometrical differences explain previous discrepancies, reviving proportional scintillation as a promising method for large LXe detectors.

Findings

Results align when geometrical factors are considered.

Discrepancies are due to geometry, not technique limitations.

Original results from Waseda group are confirmed.

Abstract

The charge read out of a LXe detector via Proportional Scintillation in the liquid phase was first realized by the Waseda group 40 years ago, but at that time the technical challenges were overwhelming. Although the tests were successful, this method was finally discarded and eventually nearly forgotten. For present day large LXe Dark Matter detectors, this approach was not even considered. Instead the Dual Phase technology was selected despite many limitations and challenges. In two independent studies the groups from Columbia University and Shanghai Jiao Tong University reevaluated Proportional Scintillation in the liquid phase. Both established the merits for very large LXe detectors, but the Columbia group also encountered apparent limitations, namely the shadowing of the light by the anode wires and a dependence of the pulse shape on the drift path of the electrons in the anode region. The discrepancies between the two studies, however, are not intrinsic to the technique, but a direct consequence of the chosen geometry. Taking the geometrical differences into account the results match without ambiguity. They also agree with the original results from the Waseda group. With the technical problems solved, the path is now open to use this method in future large LXe TPCs.