Project 8: Measuring the tritium beta-decay spectrum using Cyclotron Radiation Emission Spectroscopy

Abstract

The goal of the Project 8 experiment is to measure the absolute neutrino mass using tritium beta decays and a new spectroscopic technique, Cyclotron Radiation Emission Spectroscopy (CRES). CRES has the potential for extremely low backgrounds and high precision. Phase I of Project 8 demonstrated that CRES could be used to detect single-electron cyclotron radiation and perform precision electron spectroscopy. We are in Phase II of the experiment, performing a 2-3-month measurement of the endpoint of the tritium spectrum. We will measure the last ~2 keV of the beta-decay spectrum, demonstrate our understanding of the systematic uncertainties, and explore the background rate at energies just above the endpoint. In Phase III we will demonstrate the ability to scale up the volume of the experiment, and to create a stable atomic tritium source, which will eventually avoid systematic uncertainties from the final states of the molecule. Phase IV will combine the critical factors of precision, size, and well-controlled systematic uncertainties to reach the final sensitivity of 40 meV. I will present the status of Project 8 Phase II and the plans for Phases III and IV.