Performance and fundamental processes at low energy in a two-phase liquid xenon dark matter detector
We extend the study of the performance of a prototype two-phase liquid xenon WIMP dark matter detector to recoil energies below 20 keV. We demonstrate a new method for obtaining the best estimate of the energies of events using a calibrated sum of charge and light signals and introduce the corresponding discrimination parameter, giving its mean value at 4 kV/cm for electron and nuclear recoils up to 100 keV (nuclear recoil energy). We show that fluctuations in recombination limit discrimination for most energies, and reveal an improvement in discrimination below 20 keV due to a surprising increase in ionization yield for low energy electron recoils. This improvement is crucial for a high-sensitivity dark matter search.
Nuclear Instruments and Methods in Physics Research A
- Pub Date:
- August 2007
- Physics - Instrumentation and Detectors
- 4 pages, 6 figures, submitted to DM06 conference proceedings in Nucl Phys B