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

## TL;DR

Project 8 employs Cyclotron Radiation Emission Spectroscopy to measure the absolute neutrino mass with high precision, aiming to surpass current methods by scaling up the technique with atomic tritium.

## Contribution

This paper introduces the Project 8 experiment, demonstrating how CRES can achieve lower neutrino mass sensitivities compared to traditional MAC-E filter-based experiments.

## Key findings

- CRES can probe neutrino masses down to ~40 meV.
- Project 8 shows promising scalability for neutrino mass measurements.
- CRES offers an alternative to MAC-E filter techniques with potential for higher sensitivity.

## 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 $\mathcal{O}({\rm eV})$ resolution. A lower bound of $m(\nu_e) \gtrsim 9(0.1)\, {\rm meV}$ 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 $m(\nu_e) \lesssim 0.2\,{\rm eV}$. 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 $m(\nu_e) \lesssim 40\,{\rm meV}$ using an atomic tritium source.