Development of a liquid xenon time projection chamber for gamma‐ray astronomy

Work is in progress at the Columbia Astrophysics Laboratory on the development of a liquid xenon imaging chamber for gamma‐ray astronomy. Such an instrument will combine high detection efficiency, good energy and position resolution with a large effective area. These properties, together with the excellent background rejection capability provided by 3‐dimensional imaging, will allow orders of magnitude better sensitivity than currently used instruments, for the detection of weak gamma‐ray sources in space.We have started with studies of the maximum energy resolution achievable with noble liquid ionization chambers. A value of 26 keV FWHM for 1 MeV electrons has been measured in liquid argon, dominated mostly by recombination straggling on highly ionizing delta electrons produced in large number along the primary ionizing track.We are presently working on liquid xenon to establish the most efficient gas purification scheme and the best spectroscopic performance. The initial result of about 38 keV FWHM for ...