The electronics read out and data acquisition system for a liquid xenon time projection chamber as a balloon-borne Compton telescope

Abstract

A 10 l liquid xenon time projection chamber with a drift gap of 7 cm, was developed for imaging cosmic gamma-rays in the energy band 0.3–10 MeV. It was used for the first time as a balloon-borne instrument in two recent flights from Palestine, TX. The detector uses both the ionization and the primary scintillation signals produced by gamma-ray interactions in the liquid for an accurate measurement of the three spatial coordinates and for the energy deposition in each interaction. With this information, the arrival direction of gamma-rays fully absorbed in the liquid xenon after one or more Compton scatterings can then be reconstructed. Here we describe the electronics readout system used for the initial balloon flights of the LXeTPC operating as a Compton telescope. Data from the laboratory and cosmic gamma-ray sources acquired with this custom-designed system are presented.