Linnaeus Physics Colloquium: Probing the neutrino mass with tritium beta decay

Welcome to Linnaeus Physics Colloquium, a series of seminars delivered by renowned researchers in physics.

Title: Probing the neutrino mass with tritium beta decay
Lecturer: Prof. Dr. Kathrin Valerius, Institute for Astroparticle Physics, Karlsruhe Institute of Technology

Abstract

Precision measurements of the kinematics of weak decays offer a direct and nearly model-independent approach to probe the absolute neutrino mass scale. The KArlsruhe TRItium Neutrino experiment (KATRIN) is searching for the minute imprint of the neutrino mass in the endpoint region of the tritium beta-decay spectrum. KATRIN employs a high-intensity gaseous molecular tritium source and a high- resolution electrostatic filter with magnetic adiabatic collimation to target a neutrino-mass sensitivity of 0.2eV/c2, thus improving on previous experiments by an order of magnitude, after five years of data-taking.

With just its first science run, KATRIN has improved previous direct neutrino mass bounds by about a factor of two, yielding a new upper limit of 1.1 eV/c2 (90% CL), and has begun to address further science channels such as the direct search for light sterile neutrinos. As larger data sets are collected and further improvements in terms of signal-to-background ratio and systematics are being achieved, KATRIN is continuing along its path towards sub-eV neutrino mass sensitivity and the exploration of interesting BSM physics cases.

Based on the technological developments in direct neutrino-mass experiments, the long-standing quest for direct detection of cosmic relic neutrinos by capture on tritium nuclei has moved back into focus in recent years. In the talk, I will also give an outlook on the prospects of future cosmic neutrino searches.

References:

[1] KATRIN Collaboration, “Improved upper limit on the neutrino mass from a direct kinematic method by KATRIN” , PRL 123 (2019) 221802

[2] KATRIN Collaboration, „ Bound on 3+1 Active-Sterile Neutrino Mixing from the First Four-Week Science Run of KATRIN“, PRL 126 (2021) 091803

[3] KATRIN Collaboration, „ Analysis methods for the first KATRIN neutrino-mass measurement“, arXiv:2101.05253

About Prof. Dr. Kathrin Valerius:

Kathrin Valerius studied physics at Bonn University and obtained her doctorate at West fä lische Wilhelms-Universität Münster in 2009 working on the design of the KATRIN main spectrometer and on the development of calibration sources for the experiment . Subsequently, she changed fields from neutrinos to gamma rays and took on postdoctoral research at the Erlangen Centre for Astroparticle Physics and at APC, Paris, where she studied Galactic gamma-ray sources with the H.E.S.S. telescopes in Namibia . In 2014 Kathrin moved to KIT as leader of a Helmholtz Young Investigator Group to work on data analysis for KATRIN, and was appointed as a faculty member in 2020. With joining the XENON collaboration in 2019 the group is also broadening its research activities towards direct Dark Matter search.