New Experimental Techniques for Neutrino Experiments

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 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 so 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. Examples of possible application include detection of rare radioactive isotopes for nuclear non-proliferation, Fiertz interference term measurements, low energy electron-atom scattering, and high voltage metrology. The PI wishes to target undergraduate student participation in such research toward underrepresented minorities, particularly toward members of the Native American community.

After three years of research and development, the Project 8 experiment has successfully demonstrated the first detection of cyclotron radiation from single electrons. With the proof of principle firmly established, this award provides continued support for the next stage of the 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. Such a direct measurement in the sub-eV neutrino mass range is important for cosmology, the structure of the new Standard Model, and it will illuminate a key unknown in the search for neutrino-less double beta decay.