My research is currently focused on understanding Dark Matter through a direct detection experiment, named XENON. The existence of Dark Matter is undisputed, yet its nature remains mysterious and unexplained. The explanation is likely to involve physics beyond the standard model of particle physics (BSM). Weakly interacting massive particles (WIMPs) are one class of dark matter candidates, naturally predicted in BSM theories. WIMPs direct detection experiments such as XENON aim to measure the signals produced in a detector on Earth as a result of a WIMP-nucleon scattering. To be sensitive to such rare events, an experiment must rely on a very large target mass, extremely low background and effective signal-to-noise discrimination. XENON used liquid xenon as WIMP target and detection medium in a 3D position sensitive Time Projection Chamber (TPC). With TPCs of increasing mass and reduced background, the XENON project has been at the forefront of direct detection experiments worldwide. Results from the XENON100 detector, at the Italian Gran Sasso Laboratory (LNGS), have yielded the most stringent limits on both spin-independent and spin-dependent WIMP-nucleon cross-section. The search for dark matter with XENON100 will continue until the start of the XENON1T phase, projected to start in 2015. In its initial realization, XENON1T will use 3.5 tons of liquid xenon and is expected to give a factor of 100 improvement in sensitivity over than of XENON100, after two years of data. XENON is funded by the National Science Foundation.
An active R&D program is an integral part of my research. The present experiments aim to measure with increasing precision the properties of liquid xenon under different particle irradiation, both for the benefit of the XENON program but also for other applications where combined calorimetry and imaging are of interest. The experiments are carried out in the Cyclotron building of the Columbia University Nevis Laboratories in Irvington, NY. In my laboratory on the 10 floor of the Pupin physics building, on the Columbia's Morningside Heights campus in Manhattan, another project , also of interest to XENON, is currently in the last phase of development. It is an Atom Trap aiming at measuring traces of Krypton in Xenon at better than 1 part per trillion. The Columbia Atom Trap Trace Analysis was selected as a Major Research Infrastructure project, funded by NSF and Columbia University.