KATRIN Experiment Sets New Upper Limit On Neutrino Mass At 0.45 EV

The Karlsruhe Tritium Neutrino Experiment (KATRIN) has estimated a new upper limit on the neutrino mass while observing the disintegration of molecular tritium

The experiment set a new upper limit of 0.45 electron volts (eV) on neutrino mass, which is less than one-millionth the mass of an electron (the next-lightest known particle at 511,000 eV)

About the KATRIN Experiment

KATRIN studies the decay of tritium, a radioactive hydrogen isotope.
It tracks the energy of electrons emitted during decay to infer the neutrino’s mass.
Significance: KATRIN’s experiments results are direct, model-independent, and robust, unlike other techniques (like cosmological observations or double-beta decay experiments) which rely on theoretical assumptions.

About Neutrinos

Neutrinos are the most abundant elementary subatomic particles that have mass in the universe and belong to the leptons family of particles.
Produced: Neutrinos are produced in various nuclear processes, including nuclear fusion in stars, nuclear fission in particle reactors or accelerators, and the decay of muons.
- Bananas also emits neutrinos (coming from the natural radioactivity of the potassium in the fruit)
Types: There are 3 types of neutrinos,
- The electron neutrino, the muon neutrino, and the tauon neutrino
  - Neutrino Oscillation: Neutrinos Oscillations refer to the way neutrinos change their types or flavor as they travel
    - Neutrinos travel close to the speed of light
Key Characteristics:
- Neutrality: Neutrinos are electrically neutral, meaning they carry no electric charge.
- Neutrino Mass: Neutrinos possess an extremely small mass which has not been measured exactly until now.
  - The particle oscillations (measuring the differences in the squares of the neutrino masses) phenomenon has established that at least two types of neutrinos have more than zero mass, winning them the 2015 Nobel Prize for physics.

Why Is Neutrino Mass Important?

It helps explain why matter dominates over antimatter in the universe.
It points to new physics beyond the Standard Model.
- The Standard Model of physics previously predicted Neutrinos to be massless.
Measuring neutrino mass may reveal the existence of new forces or particles.
It is crucial for understanding the evolution of the early universe.

- Spin: They have a spin of 1/2, making them fermions.
- Interaction: Neutrinos primarily interact through the weak force, which is responsible for certain types of radioactive decay.
- Interaction with Matter: Neutrinos rarely interact with other matter which means they can pass through almost anything.
- Helicity: Neutrinos and their antiparticles (antineutrinos) are distinguished by their helicity (spin direction relative to their momentum). Neutrinos are typically left-handed, while antineutrinos are right-handed.

Experiments on Neutrinos

The Karlsruhe Tritium Neutrino Experiment (KATRIN): It aims to directly measure the neutrino mass.
PROSPECT and the Fermilab Short-Baseline Neutrino program: It use neutrinos from reactors and accelerators to search for unknown types of neutrinos beyond the three
MAJORANA Demonstrator experiment: It is placed deep under the Earth’s surface to determine whether neutrinos are their own antiparticle or not.
The NOvA experiment and the international Deep Underground Neutrino Experiment: It aims to study the phenomenon of “neutrino oscillation,” which looks at how mass differs between different types of neutrinos.

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