Nuclear Particle Astrophysics (NPA) Seminar, Luke Goetzke, Columbia University, “Search for Dark Matter Annual Modulation with XENON100 Electronic Recoils”

Thursday Sep 17, 2015, 3:30 PM → 4:30 PM US/Eastern

WLC 108

The telltale signature of dark matter is an annual modulation of the event rate in a terrestrial detector due to the motion of the Earth around the Sun. But what type of events will they be? Experimental efforts have focused on the search for nuclear recoils. However, null results from these experiments, including XENON100, strongly challenge the nuclear recoil interpretation of the DAMA/LIBRA annual modulation. Another possibility is that this annual modulation is instead due to electronic recoils, i.e. that dark matter is leptophilic.

In this talk, I will present recent results of a search for periodic signatures in the electronic recoil data from XENON100. These results challenge the electronic recoil interpretation of the DAMA/LIBRA annual modulation, and demonstrate the impressive background level and long-term stability so far achieved with liquid xenon (LXe) detector technology.

I will also discuss new experimental efforts to characterize low-energy electronic recoils in LXe. The uncertainty on the recent XENON100 results is dominated by systematic uncertainties on the energy scale. For next generation dark matter detectors using LXe, an improved understanding of low-energy interactions is crucial. In particular, measurements are needed of the dependence of the light and charge yield of LXe on the applied electric field. I will present results of recent measurements of the light and charge yield of electronic recoils in LXe using a specially designed time projection chamber at Columbia University. The energy and field dependence of the yields was measured as a function of drift field down to very low recoil energies and with relatively high precision.

Goetzke_NPA_Seminar_09172015.pdf