Revised performance parameters of the ZEPLIN-III dark matter experiment

Understand

This note presents revised detector parameters applicable to data from the First Science Run of the ZEPLIN-III dark matter experiment; these datasets were acquired in 2008 and reanalised in 2011.

• This run demonstrated electron recoil discrimination in liquid xenon at the level of 1 part in 10,000 below 40 keV nuclear recoil energy, at an electric field of 3.8 kV/cm; this remains the best discrimination reported for this medium to date.
• Building on relevant measurements published in recent years, the calibration of the scintillation and ionisation responses for both electron and nuclear recoils, which had been mapped linearly to Co-57 gamma-ray interactions, is converted here into optical parameters which are better suited to relate the data to the emerging liquid xenon response models.
• Additional information is given on the fitting of the electron and nuclear recoil populations at low energy.