NSF Award
1649966
Multiple astronomical observations have established that about 85% of the matter in the universe is not made of normal atoms, but must be otherwise undetected elementary "dark matter" particles that do not emit or absorb light. Deciphering the nature of this so-called Dark Matter is of fundamental importance to cosmology, astrophysics, and high-energy particle physics. A leading hypothesis is that it is comprised of Weakly Interacting Massive Particles, or WIMPs, that were produced moments after 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. Direct detection of WIMP dark matter would solve a fundamental mystery and provide a unique window to learning about the primary matter constituent of the Universe and of physics beyond the Standard Model of particle physics. Directional dark matter detectors have access to a smoking-gun signature of dark matter: the ability to study the angular distribution of recoils induced by WIMPs. At present, the sensitivity of directional detectors lags behind their non-directional counterparts. This award will provide funding for the research team to develop a directional detector technology capable of reconstructing WIMP-induced recoils with high precision, thus enhancing the sensitivity of direction-sensitive detectors.<br/><br/>The detector under evaluation in this study is likely to be of wider benefit to society, with applications in the broader field of experimental particle physics (e.g. particle tracking at colliders and coherent elastic neutrino-nucleus scattering). Such detectors also have applications in space-based X-ray polarimetry. Broader impacts of this work also include the training of a diverse set of female undergraduate students at Wellesley College. By integrating students at Wellesley in all aspects of this experimental particle physics program, the proposed work will broaden the participation of members of underrepresented groups in physics.<br/><br/>In the past year, several unexpected, transformative discoveries were made in negative-ion time projection chambers (NITPCs), potentially affording a leap in directional sensitivity by two orders of magnitude per unit detector volume. Additionally, detector readouts from liquid-argon neutrino detectors are now known to work in NITPCs, making it feasible to instrument thousands of detector channels at low cost. With this award, this team will leverage these advances by building a prototype directional NITPC with high spatial resolution and low energy threshold to undertake a suite of fundamental measurements to quantitatively assess the prospects for this technology.
