Projectile-dependent scintillation of a liquid phase argon-xenon mixture

The ratio of the scintillation intensity in the near-infrared (NIR) and in the vacuum-ultraviolet (VUV) from liquid argon with a volumetric fraction of 10 − 5 of xenon (10 ppm) was studied with ion-beam excitation. Hydrogen, lithium, carbon, sulfur, and iodine ions from the Munich Tandem accelerator were used for excitation. Average linear energy transfer (LET) values from 4.4 to 3500 MeV /mm were tested by the experiments. A variation of the NIR to VUV intensity ratios by a factor of ∼ 20 was observed. This is a promising result for the development of liquid argon-xenon detectors with sole optical particle identification and background reduction in rare-event physics. The results are interpreted on the basis of energy deposition around the particle tracks.