Neutrinos are amongst the most abundant particles in the Universe, they are keys to many astrophysical processes, and they may hold the key to explaining the matter-antimatter asymmetry of the Universe. They are known to occur in nature in three types, or "flavors." It has also been observed that neutrinos could switch flavors through a process known as neutrino oscillation. From such oscillation experiments, it is found that neutrinos must have a non-zero mass. This is the first known indication that there is physics beyond the very successful Standard Model of Particle Physics. Neutrino mass remains one of the most important open questions in physics and experiments are searching for ways to determine it since with their abundance they could play an important role in the evolution of our Universe. Direct laboratory determinations based on the precise measurement of the beta spectrum have been expanding over the past 80 years due to increasingly powerful electron spectrometry techniques. In 2009, the PI proposed a new technique by which the energy spectrum of low energy electrons can be extracted. The technique, known as Cyclotron Radiation Emission Spectroscopy (CRES), relies on the detection and measurement of coherent radiation created from the cyclotron motion of electrons in a magnetic field. 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, with potential applications in nuclear reactor monitoring and direct dark matter detection. Research engagement with undergraduate students is facilitated by MIT's Undergraduate Research Opportunity Program (UROP), which connects students and faculty and allows students to engage in basic research throughout the academic year.
In 2009, the PI proposed a new technique by which the energy spectrum of low energy electrons can be extracted. The CRES technique relies on the detection and measurement of coherent radiation created from the cyclotron motion of electrons in a magnetic field. Such a frequency-based technique has the capability of overcoming many of the limitations imposed by traditional spectroscopic techniques used in direct neutrino mass experiments using tritium. The Project 8 experiment, of which the PI is the spokesperson, has now successfully demonstrated how the CRES technique is effective in precisely measuring the kinetic energy of electrons emitted from a radioactive gas. With the proof of principle firmly established, this award provides continued support of the next stage of Project 8's R&D program, moving toward a neutrino mass measurement from tritium beta decay. In particular, the next phase is to make a first measurement of a tritium beta spectrum in order to determine the scalability of the technique. Research will also continue to determine the technique's ultimate capability: to probe the inverted neutrino mass scale.
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.
