Measurement of the ionization and scintillation yield of nuclear recoils in liquid xenon

The XENON experiment uses liquid xenon as target and detector to look for dark matter weakly interacting massive particles (WIMPs) through their elastic scattering off Xe nuclei. With a fiducial mass of 1000 kg of liquid xenon, a sufficiently low threshold of 16 keV recoil energy and an un-rejected background rate of 10 events per year, XENON would be sensitive to a WIMP-nucleon interaction cross section of ∼ 10^-46 cm², for WIMPs with masses above 50 GeV. Using time projection chambers operating in dual (liquid/gas) phase, XENON simultaneously detects the ionization, through secondary scintillation in the gas, and primary scintillation in the liquid produced by low energy recoils. We present some results from experiments using prototypes irradiated with neutrons to measure the ionization and scintillation yield of low energy nuclear recoils in liquid xenon.