Development of the LZ Dark Matter Experiment

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A broad range of astrophysical and cosmological observations indicates that 80% of the matter in the universe is in a new form which does not emit or absorb light, and has not yet been encountered in the laboratory. Many physics models suggest that the dark matter may be composed of one or more previously unobserved Weakly Interacting Massive Particles, or WIMPs. The astrophysical detection of such a particle through its interactions in a terrestrial particle detector would have a profound impact on cosmology and fundamental interactions, while also giving rise to a new type of observational astrophysics. This work supports key research and development and design efforts toward construction of a 7-ton liquid Xenon dark matter detector, known as 'LZ', to be installed at the 4850 level of the Sanford Underground Research Facility in Lead, South Dakota. This detector will use established liquid Xenon Time Projection Chamber technology with read out of primary and secondary scintillation signals for particle identification, together with 3-d position reconstruction to exploit the self-shielding of the liquid Xenon, removal of surface artifacts and calibration of position-dependent response functions. The experiment will take advantage of existing infrastructure and detector components from the LUX experiment, which is currently being deployed into the mine, allowing a rapid turn-around at the conclusion of that experiment's life. Broader Impacts By exploiting the natural curiosity of the public in dark matter as well as the connection and familiarity with gravity, this project will provide a rich environment in which to develop a range of activities from tours and displays to partnerships with local schools and individuals, aimed at fostering an interest in science and science careers. Through both LUX and LZ programs, the collaboration will continue to play a key role in the efforts at Sanford in education and public outreach programs. Dark matter science also demands the development of new technologies that are ultra-sensitive to radiation and new methods for achieving ultra-low radioactive backgrounds. There is direct overlap with the methods used in a wide range of nuclear security and medical imaging contexts. The instrument that will be developed will also provide direct educational and training benefits at the undergraduate, graduate and postdoctoral levels, and will promote basic science research by providing access to non-Ph.D. granting institutions, particularly those in geographical proximity to Lead, SD.