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What is the KATRIN Experiment?
- Full form: Karlsruhe Tritium Neutrino Experiment.
- Objective: To directly measure the absolute mass of neutrinos — the lightest known massive particles.
- Located in Karlsruhe, Germany, its core spectrometer was built in Deggendorf and transported over 8,600 km via rivers and seas due to its 200-tonne weight.
What are Neutrinos?
Neutrinos are fundamental subatomic particles with no electric charge and extremely tiny mass.
They come in three types (or flavours): electron neutrino, muon neutrino, and tau neutrino.
They are abundant in the universe, produced in the Sun, stars, nuclear reactors, and radioactive decay.
Because they interact very weakly with matter, they can pass through Earth without being stopped — making them very difficult to detect.
According to the Standard Model, neutrinos should be massless. But experiments on neutrino oscillations show that they do have mass, though tiny — pointing to new physics beyond the Standard Model.
What Did KATRIN Do?
- KATRIN analyzes beta decay of tritium to determine how much energy is carried away by the emitted electrons.
- Beta decay is a type of radioactive decay in which an unstable nucleus emits an electron (beta particle) and an antineutrino.
- By studying the energy spectrum of 36 million electrons, it inferred an upper limit on the sum of neutrino masses.
- It uses no cosmological or theoretical assumptions, making its result model-independent and robust.
Why It Matters:
- Knowing the mass of neutrinos helps in:
- Understanding the evolution of the universe and galactic structure.
- Exploring if neutrinos are their own antiparticles (Majorana particles), which could explain matter-antimatter asymmetry in the universe.
- Probing new physics beyond the Standard Model.
Why in News?
- The KATRIN experiment has recently set a new upper limit on the sum of the masses of all three neutrino types — no more than 8.8 × 10⁻⁷ times the mass of an electron, improving upon its previous record.
