Response of the XENON100 dark matter detector to nuclear recoils

Results from the nuclear recoil calibration of the XENON100 dark matter detector installed underground at the Laboratori Nazionali del Gran Sasso, Italy are presented. Data from measurements with an external AmBe241 neutron source are compared with a detailed Monte Carlo simulation which is used to extract the energy-dependent charge-yield Qy and relative scintillation efficiency Leff. A very good level of absolute spectral matching is achieved in both observable signal channels—scintillation S1 and ionization S2—along with agreement in the two-dimensional particle discrimination space. The results confirm the validity of the derived signal acceptance in earlier reported dark matter searches of the XENON100 experiment.