The Quest for Dark Matter

Cristiano Galbiati Princeton University

There is a wide range of astronomical evidence that the visible stars and gas in all galaxies, including our own, are immersed in a much larger cloud of non-luminous matter, typically an order of magnitude greater in total mass. The existence of this ?dark matter? is consistent with evidence from large-scale galaxy surveys and microwave background measurements, indicating that the majority of matter in the universe is non-baryonic. The nature of this non-baryonic component is still totally unknown, and the resolution of the ?dark matter puzzle? is of fundamental importance to cosmology, astrophysics, and elementary particle physics. A leading explanation, motivated by supersymmetry theory, is the existence of as yet undiscovered Weakly Interacting Massive Particles (WIMPs), formed in the early universe and subsequentlyclustered in association with normal matter. WIMPs couldbe detected in terrestrial experiments by their collisions withordinary nuclei, giving observable low energy (<100 keV) nuclearrecoils. The predicted low collision rates require ultra- low background detectors with large (0.1?10 ton) target masses, locatedin deep underground sites to eliminate neutron background fromcosmic ray muons.The new generation of Dark Matter experiments promises to probe themost interesting region of parameters for the Dark Matter candidates. I will review and describe a number of current andfuture efforts at Princeton University dedicated to a comprehensive direct search for Dark Matter.  They include operation of theWARP-140 detector at LNGS, construction of large depleted argondetectors, development of radiopure NaI detectors, and thedevelopment of the "MAX - Multi-Ton Argon and Xenon" program at the forthcoming Deep Underground Science and Engineering Laboratory (DUSEL).