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Improved Upper Limit on the Neutrino Mass from a Direct Kinematic Method by KATRIN
M Aker1,2, K Altenmüller3,4,5, M Arenz6
1Institute for Nuclear Physics (IKP), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany.
Physical Review Letters
|December 24, 2019
Summary
The KATRIN experiment measured neutrino mass using tritium beta decay, yielding an upper limit of 1.1 eV. This result significantly improves previous limits for neutrino mass.
Area of Science:
- Particle Physics
- Cosmology
- Astroparticle Physics
Background:
- Determining the absolute neutrino mass is crucial for understanding particle physics and the evolution of the universe.
- Previous measurements have provided indirect constraints, but direct kinematic measurements offer model-independent results.
Purpose of the Study:
- To report the first neutrino mass measurement from the Karlsruhe Tritium Neutrino (KATRIN) experiment.
- To derive an upper limit on the absolute neutrino mass scale.
Main Methods:
- Utilizing a high-purity gaseous molecular tritium source.
- Employing a high-resolution MAC-E filter for precise energy analysis of beta-decay electrons.
- Fitting the electron spectrum near the kinematic endpoint (18.57 keV).
Main Results:
- An effective neutrino mass squared value of (-1.0_{-1.1}^{+0.9}) eV² was obtained.
- An upper limit of 1.1 eV (90% confidence level) on the absolute neutrino mass was derived.
- This result matches the KATRIN sensitivity and nearly halves previous kinematic measurement limits.
Conclusions:
- The KATRIN experiment has successfully provided a leading direct constraint on neutrino mass.
- The derived upper limit offers valuable model-independent input for cosmological structure formation studies.
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