Xenon Looks for Modulating WIMP Signal in Electron Recoils

Xenon has a new paper out looking for an annual modulation in the spectrum of electron recoils in their detector. This is a potentially interesting work because it tests an alternative explanation of the DAMA signal. If instead of interacting with nuclei, WIMP dark matter interacts with electrons, DAMA might still see a signal while most direct detection searches, which look exclusively for nuclear recoils, won’t see anything. Electron analyses are difficult with most low-background dark matter detectors because things like beta decay products will contaminate the signal. Their result clearly seems to exclude the electron recoil hypothesis for the DAMA result, although they also appear to exclude 0-amplitude¬†at over a 99% confidence level. The best phase, however, is quite far from the expected phase of a dark matter signal, so this may not be anything interesting in the end.