Neutrino
A neutrino is an elementary particle with no electric charge and very little mass.[1] It is a fundamental particle, which means that, as far as scientists know, it is not made of any smaller pieces.[2] Neutrinos belong to the same group of particles as the electron, the leptons.[3]
Neutrinos are the lightest of all the subatomic particles that have mass, and they are the most common particle with mass in the universe.[4] The physicist Enrico Fermi made the name popular; it is Italian for "little neutral one".[5]
History
Neutrinos were first predicted in 1930, but they were not found in experiments until 1956. For many years after that, scientists thought they had no mass at all.[6]
Types
There are three types, or "flavours", of neutrino: the electron neutrino, the muon neutrino and the tau neutrino. Each is paired with a charged lepton: the electron, the muon and the tau.[7] Experiments have found that neutrinos can change from one type to another as they travel, an effect called neutrino oscillation.[8]
How neutrinos interact
Neutrinos interact only through gravity and the weak force. Because the weak force acts only over very short distances, neutrinos can pass straight through the atoms of solid objects, and most of them pass right through the Earth without hitting anything.[9] They are often produced when heavy particles turn into lighter ones, a process called decay.[10] To catch them, scientists build very large detectors and make intense sources of neutrinos.[11]
See also
References
- ↑ "What's a neutrino?". All Things Neutrino. Fermilab. Retrieved 20 October 2026.
But while electrons have a negative charge, neutrinos have no charge at all. Neutrinos are also incredibly small and light.
- ↑ "What's a neutrino?". All Things Neutrino. Fermilab. Retrieved 20 October 2026.
It's one of the so-called fundamental particles, which means it isn't made of any smaller pieces, at least that we know of.
- ↑ "The Standard Model". CERN. Retrieved 20 October 2026.
the "electron" and the "electron neutrino", the "muon" and the "muon neutrino", and the "tau" and the "tau neutrino"
- ↑ "What's a neutrino?". All Things Neutrino. Fermilab. Retrieved 20 October 2026.
They are the lightest of all the subatomic particles that have mass. They're also extremely common—in fact, they're the most abundant massive particle in the universe.
- ↑ "What's a neutrino?". All Things Neutrino. Fermilab. Retrieved 20 October 2026.
Physicist Enrico Fermi popularized the name "neutrino", which is Italian for "little neutral one."
- ↑ "What's a neutrino?". All Things Neutrino. Fermilab. Retrieved 20 October 2026.
First predicted in 1930, they weren't discovered in experiments until 1956, and scientists thought they were massless until even later.
- ↑ "The Standard Model". CERN. Retrieved 20 October 2026.
The six leptons are similarly arranged in three generations
- ↑ "33.4 Particles, Patterns, and Conservation Laws". College Physics 2e. OpenStax. Retrieved 20 October 2026.
due to neutrino "oscillations," or transformations of neutrinos from one family type to another.
- ↑ "What's a neutrino?". All Things Neutrino. Fermilab. Retrieved 20 October 2026.
Most neutrinos will pass through Earth without interacting at all.
- ↑ "What's a neutrino?". All Things Neutrino. Fermilab. Retrieved 20 October 2026.
are often the product of heavy particles turning into lighter ones, a process called "decay."
- ↑ "What's a neutrino?". All Things Neutrino. Fermilab. Retrieved 20 October 2026.
To increase the odds of seeing them, scientists build huge detectors and create intense sources of neutrinos.