RUI: Collaborative Research: Improved Limits from DRIFT and R&D Towards Improved Directionality and Sensitivity

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In this era of precision cosmology, measurements suggest that ordinary matter represents only a fraction of the total matter density in the Universe. The rest, whose effect we can see only gravitationally, is unknown in its nature and is termed Dark Matter. Particle physics models suggest that dark matter is composed of relic Weakly Interacting Massive Particles, or WIMPs, left over from the Big Bang. If WIMPs are the dark matter, then their presence in our galaxy may be detectable via scattering from atomic nuclei in detectors located deep underground to help reject backgrounds due to cosmic rays. Experimental efforts to detect WIMPs are extremely challenging due to the predicted small interaction probabilities and the existence of backgrounds that mimic the expected signal. Fortunately, a number of unique dark matter signatures exist that can be used to discriminate against backgrounds and decisively identify WIMP interactions. The largest and most robust signature is the predicted dependence of the WIMP flux on the Sun-Earth velocity through the Galaxy, yielding a sidereal modulation of the nuclear recoil direction in the laboratory. The Directional Recoil Identification From Tracks (DRIFT) dark matter experiment is a leader in the field of directional dark matter detection, with sensitivity to the powerful angular signature of nuclear recoils induced by WIMPs. The intellectual merit of this award resides in DRIFT's powerful capabilities being brought to bear on one of the most important questions in science today. The collaboration will be testing their next prototype detector, DRIFT-IIe, above ground at Occidental College. It features an inherently scalable design including a redesigned field cage, a texturized, thin-film cathode, a new, transparent wire readout which doubles the fiducial volume per readout, and a new every-wire data acquisition system which allows for lower noise and fiducialization in the detector plane. The potential of DRIFT's capabilities have promising applications to Homeland Security and double-beta decay experiments. Broader impacts of this work also include the training of a diverse set of undergraduate and graduate students (including underrepresented minorities) in increasingly rare small-scale experiments, giving them exposure to a wide range of research experience.