Karlsruhe Tritium Neutrino Experiment (KATRIN)

Karlsruhe Tritium Neutrino Experiment (KATRIN): Recently, the KATRIN collaboration announced a new and more stringent upper limit on the combined mass of the three known types of neutrinos.

• About Neutrinos: Electrically neutral subatomic particles produced in processes like radioactive decay and nuclear reactions in stars, including the sun.

o Fundamental particles in the Standard Model of particle physics (exact mass is still unknown)

o Extremely lightweight, with masses less than a millionth of an electron’s mass.

o 3 known types of neutrinos: electron neutrino, muon neutrino, and tau neutrino.

• About KATRIN Experiment: Located in Karlsruhe, Germany and aims to precisely measure the mass of the electron antineutrino, a neutrino type produced during beta decay.

o The experiment studies the decay of tritium (a radioactive hydrogen isotope), which emits an electron and an electron antineutrino.

• By analyzing the energy of emitted electrons, researchers can infer the upper limit of the neutrino's mass.
• Recent Findings: Total neutrino mass is now constrained to less than 0.45 electron volts (eV).

o Researchers found it cannot exceed 8.8 × 10⁻⁷ times the mass of an electron — a twofold improvement over previous lab-based limits.

o This marks a nearly 50% reduction from KATRIN’s earlier estimates.