Particle Astrophysics at Yale: The LUX Dark Matter Search

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This award provides funds for this Yale University group to contribute to the LUX-350 dark matter experiment. LUX-350 promises substantially improved sensitivity to the existence of Weakly Interacting Massive Particles (WIMPs), a theoretically attractive explanation for the nature of the missing dark matter. LUX-350 is a two-phase (liquid/gas) xenon experiment, with a total liquid xenon (LXe) mass of 350 kg and a fiducial mass of 100 kg. The LUX-350 detector exploits a number of features of LXe to drive backgrounds down. The active detector volume permits the full reconstruction of event energy deposition and position. Crucially, the background rate is heavily suppressed in the fiducial volume due to the active shielding by the surrounding LXe, and decreases with increasing LXe mass. Integration of LUX-350 will take place at a newly renovated surface facility at SUSEL, the Sanford Underground Science and Engineering Laboratory at Homestake before moving underground.On LUX-350, Yale is responsible for the xenon purification system, the 100 kV cathode high voltage system, slow control electronics, and radioactive source manipulators for detector calibration. The group has also developed a method of calibrating LXe detectors using Kr-83 atoms dissolved in the LXe, and performed a new measurement of the scintillation efficiency and charge yield for nuclear recoils in LXe. Broader Impact: Development of technology related to LXe will find use in the increasing number of experiments worldwide using noble liquids as detection materials. These projects will also result in technical training in radiation detection, cryogenics, and gas purification for graduate and undergraduate students. LXe has practical applications to gamma ray imaging for astrophysics, Homeland Security, and medical imaging, as well as for fast neutron detection.