New Experiment Techniques For Neutrino Physics

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Two remarkable paradigm shifts have taken place over the past twenty years in neutrino physics and cosmology. With regard to neutrino physics, or more precisely on the question of neutrino mass, the field has shifted from discovery to precision. Measurements gathered from solar, atmospheric, and reactor neutrinos have shown conclusively that neutrinos change flavor and, as a consequence, have a very small but nonzero mass. The measurements on these oscillation parameters are now being probed at the few percent level. Almost concurrently, observational cosmology has made a similar phase transition into precision measurements, providing an outstanding view of the cosmos. Precision measurements on the energy and matter content and evolution of the universe now allow detailed tests of cosmological models that were simply unavailable even a decade ago. Investigators are finally reaching the stage in which direct comparisons between neutrino masses as determined by cosmology and as determined by nuclear experiments are possible. These new advances compel the field to develop techniques that push the boundaries of neutrino mass sensitivity. The Neutrino group at MIT is leading a next-generation neutrino mass experiment called Project 8 that utilizes an entirely new approach in neutrino mass measurements. By using frequency to measure energy, one can extract exquisite spectroscopic information. The collaboration has demonstrated that the Cyclotron Radiation Emission Spectroscopy (CRES) technique extracts the energy of electrons created from a radioactive gas and has shown that the technique also works on tritium beta decay. Knowledge of neutrino masses has broad implications for the scientific community, particularly in the fields of nuclear physics, particle physics, and cosmology. The CRES technique, being a general spectroscopic technique for low energy electrons, has broad applicability. The use of metallic superconducting bolometers for recoil detection also has broad reach, having potential applications in nuclear reactor monitoring and direct dark matter detection. These topics have and continue to draw broad support and engagement from undergraduate students in physics.The collaboration is now expanding the CRES technique to build a new beta decay experiment with improved sensitivity for the neutrino mass scale. The goal of the Project 8 experiment is to push the neutrino mass sensitivity down to 40 meV/c^2 at 90% confidence limit. The MIT Neutrino Group is also pushing a novel technology designed to detect low energy recoils created in neutrino interactions from coherent elastic neutrino nucleus scattering. Specifically, they are developing metallic superconducting bolometers with thresholds sufficiently low as to enable detection of coherent scattering from reactor neutrinos. The new experimental effort, Ricochet, has potential applications in searching for new physics and even nuclear reactor monitoring. The experiment has recently been approved to be deployed at the ILL reactor in Grenoble, France.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.