PIXeY (Particle Identification in Xenon at Yale) is a two-phase (liquid/gas) xenon prototype time projection chamber
with 3 kg active mass. PIXeY was built to optimize energy resolution and gamma/neutron discrimination, with a number
of technological improvements over previous work. Parallel-wire grids, which control the drift and proportionalscintillation
fields, are optimized both for light collection efficiency and field uniformity. High quantum efficiency
Hamamatsu R8778 PMTs, high-reflectivity Teflon walls, and charge-light anti-correlation techniques are also
incorporated. The first run of the detector has concluded, where all systems were tested both using LED calibration
methods as well as using sources for calibration and spectral measurements. Ultimately our results were limited by PMT
calibration issues, low light collection caused by saturation, and low drift fields constrained by high voltage hardware.
The second run of the detector is currently underway with several improved components. The feedthroughs for higher
voltages have improved to allow a much higher operating voltage, new PMT bases for more stable operation have been
installed, and three new grids with transparencies between 92% and 97% have been added. Once the energy resolution
studies have concluded, PIXeY will serve as a platform for future improvements, including multiple optical volumes and
single wire readout for R&D on gamma-ray imaging.