Session T2: Invited Session: Dark Matter: Direct Detection

New Results from The Search for Dark Matter with XENON100

We report new results from the XENON100 dark matter experiment searching for WIMPs. Operating underground at the LNGS in Italy, XENON100 is a dual phase (liquid/gas) time projection chamber containing a total of 161 kg liquid xenon (LXe) with a 62 kg WIMP target mass and 99 kg shield. Initial results obtained from only 11.2 days of data acquired during a commissioning period at the end of 2009 resulted in world-competitive limits on the WIMP-nucleon interaction cross-section. With no evidence of signal, recently published results from 100.9 live-days set the most stringent limit on dark matter interactions to date, excluding cross-sections above 7.0E-45 cm$^{2}$ for a 50 GeV/c$^{2}$ WIMP mass at 90\% C.L. Following this exposure, in the Summer of 2010, XENON100 was filled with Xe processed through a dedicated cryogenic distillation column to reduce Kr background to levels demonstrated in the 11.2 day commissioning period. The trigger threshold was also lowered and the electron lifetime has improved. Blinded data taking was resumed under these conditions. With excellent stability and performance throughout, the exposure approaches 200 live days at the time of writing. Results from this 200 day WIMP search dataset will be presented.   

Searching for the Dark Matter Wind: Recent Progress in Directional Detection

The nature of dark matter is one of the fundamental questions in physics today. Several experiments have recently claimed signals consistent dark matter interactions, although none are yet independently confirmed. Directional detection seeks to correlate a dark matter candidate nuclear recoil signal, in a detector deep underground, with the earth's motion through the galactic halo. The unique angular signature of the dark matter wind, which is distinct from all known backgrounds, has potential to make a definitive identification of dark matter. The design strategy of directional detectors emphasizes tracking at energies below 100 keV, in order to reconstruct WIMP-induced nuclear recoil tracks, and thereby determine the direction of incident dark matter particles. This talk will review the experimental technique and current status of directional searches.   

Dark Matter Theory Confronts the Data

Where and how we look for dark matter is intimately tied to our ideas of dark matter, and conversely, hints from experiment can push theory in new directions. I will review the basic ideas of dark matter and how they have changed over recent years. I will discuss how, irrespective of existing results, this promises to be an exciting time from the perspective of theory. Light WIMPs and WIMPs with non-standard interactions have become more prominent of late, as results from recent experiments have pushed our thinking in new directions. I'll discuss these models as well, and whether they can allay tensions between existing direct search results.