Determining the neutrino mass with Cyclotron Radiation Emission Spectroscopy - Project 8

Abstract

The most sensitive direct method to establish the absolute neutrino mass is observation of the endpoint of the tritium beta-decay spectrum. Cyclotron Radiation Emission Spectroscopy (CRES) is a precision spectrographic technique that can probe much of the unexplored neutrino mass range with $\mathcal{O}(\mathrm{eV})$ resolution. A lower bound of $m(\hat{I}{½}_e)\gtrsim 9(0.1)\mathrm{meV}$ is set by observations of neutrino oscillations, while the KATRIN Experiment - the current-generation tritium beta-decay experiment that is based on Magnetic Adiabatic Collimation with an Electrostatic (MAC-E) filter - will achieve a sensitivity of $m(\hat{I}{½}_e)\lesssim 0.2\mathrm{eV}$. The CRES technique aims to avoid the difficulties in scaling up a MAC-E filter-based experiment to achieve a lower mass sensitivity. In this paper we review the current status of the CRES technique and describe Project 8, a phased absolute neutrino mass experiment that has the potential to reach sensitivities down to $m(\hat{I}{½}_e)\lesssim 40\mathrm{meV}$ using an atomic tritium source.

19 pages, 8 figures, to be published in Journal of Physics G