Weighing a Ghost: The Quest to Measure the Neutrino Mass

Walter Pettus
Indiana University

Abstract

The ghostly neutrinos remain the only fundamental fermions whose masses are unknown. Neutrino flavor transformation measurements definitively demonstrate neutrinos have mass, breaching the Standard Model of Particle Physics, but cannot determine that mass scale. Searches capable of directly probing the neutrino mass now indicate neutrinos are at least six orders of magnitude lighter than the next fermion.

In this talk, I will review progress in the field of direct neutrino mass experiments. I will focus on advances by Project 8, an experimental concept based on the novel Cyclotron Radiation Emission Spectroscopy (CRES) technique. Project 8 has recently published its first measurement of the tritium beta spectral endpoint, enabling the first RF-based direct neutrino mass limit while demonstrating high precision spectroscopy. An R&D campaign is now underway to demonstrate scalability of the CRES technique and to develop the atomic tritium source required. Building on these successes, a next-generation experiment is envisioned with neutrino mass sensitivity down to 40 meV, covering the inverted mass ordering region.

Timbits, coffee, tea will be served in STI A before the colloquium.