What is a Neutrino? Definition, Concept and Parts of an Neutrino

What is a neutrino?

The neutrino in a very light particle. No electrical charge. The neutrino interacts through the weak force. For this reason and because it is electrically neutral, neutrino interactions with matter are very rare.


The neutrino, elementary particle of matter, is a billion times more numerous in the universe that each of the components of atoms, but it is still incredibly difficult to detect.

They are extremely abundant elementary particles in the Universe that move almost at the speed of light and interact with almost nothing in the Universe.

They are elementary because they are not made up of smaller particles. They have no electrical charge and hardly any mass.

By not interacting electrically with the atoms, they can cross the matter without being disturbed. This is why they are known as ‘ghost particles’.

Neutrinos are very, very small particles, like electrons, that move almost at the speed of light, and interact with almost nothing in the universe.

In fact, if they were not needed to explain neutron decay, we could do without them.

What are neutrinos?

We live surrounded by neutrinos. Billions of these tiny particles pass through our body at all times, but they are imperceptible, although they do not cease to interact with matter, but they are very small, impossible to measure in the 1930s, when physicist Wolfgang Pauli raised the presence of particles without mass, charge or significant interaction that, however, had interference in the loss of energy and matter of neutrons.

After photons, neutrinos are the most abundant particles in the universe; some were created from the Big Bang, others are generated in the various processes of the earth and space, both small and large scale – from a stellar explosion to inside our bodies, when an average of 5,000 neutrinos are released per second when a potassium isotope decomposes.

Despite the abundance of these particles in the universe, their existence was in doubt for decades.

There was no way to prove its existence, but there was reason to believe in an abundant but imperceptible phenomenon.

Where neutrinos originate

The neutrino, which has intrigued physicists since the 1960s, has no electrical charge and can thus pass through walls.

Every second, 66 billion of these particles pass through the equivalent of a human fingernail. And yet a neutrino emitted by the Sun has a 100 million chance of stopping on Earth.

Emitted by stars and the atmosphere, neutrinos can also be created by radioactivity called beta, as in nuclear power plants.

When a proton is transformed into a neutron (electrically neutral) or a neutron into a proton, this mutation is accompanied by the emission of a negative or positive electron and a neutrino (or an”antineutrino”).

Why are they called neutrinos?

the name was given to Italian physicists who presented it as a diminutive of the neutron. Its existence was proposed in 1930 by the Austrian Wolfgang Pauli to explain a phenomenon called beta disintegration, which he initially called neutron.

Two years later, however, another much more massive electrically neutral particle was discovered that was also called neutron (a name it has retained to this day) and to distinguish it, the Italian physicist Edoardo Analdi jokingly called it neutrino in an informal conversation with Enrico Fermi.

Fermi, who was a physicist of great prestige, liked the name and adopted it to talk about the particle from 1932 onwards.

Where do the neutrinos come from?

It is estimated that the Sun produces about 1038 neutrinos per second (That’s a lot!). One billion of these neutrinos pass through the Earth without reacting with anything (they may be passing through your hands right now!). Huge detectors are able to find some neutrinos.

The vast majority of neutrinos that reach the Earth come from nuclear reactions that take place inside the Sun. Also, significant sources of neutrinos are supernova explosions of distant stars, background radiation from the universe or reactions from nuclear power plants.

Neutrinos are also released when cosmic gamma rays collide with the Earth’s atmosphere. Other sources of neutrinos are exploding stars called supernovae, neutrinos left over from the Big Bang (according to the current theory of the origin of the universe) and atomic power plants.

Are neutrinos almost as fast as light?

The neutrinos are moving too fast. So fast that its speed approaches that of light but does not reach it. Since no body with mass can move at the speed of light, this is an indication that they have mass.

How can they be detected if they do not interact with matter?

The vast majority of neutrinos pass through the vast majority of atoms without interaction. But very rarely does any neutrino collide with any of the particles of an atom.

From the collision, energy is released and from this energy, new particles are created. If the collision is detected in a detector, it can be deduced whether a neutrino has been involved from the trace of the particles that are born.

How to catch a Neutrino

Neutrinos are so light and slippery that they can pass through a solid lead light year without clouding their hair. And yet scientists have managed to catch them.

A hundred metres underground, in a laboratory on the outskirts of Chicago (USA), there is a cave that houses a metal container the size of a bus, full of lights, measuring instruments and cables. It’s a neutrino detector.

These subatomic particles hold several records in the field of physics. They are the most abundant corpuscles of matter in the universe and yet they are still a puzzle.

This is because they are also the smallest, which prevents them from being studied directly.

No one knows what its mass is, but experiments indicate that it must be at least 100,000 times less than that of the electron, which is the next lighter particle. They also have no electrical charge, so they rarely interact with other bodies.

In Chicago, he is buried 800 kilometers away at the Soudan mine in Minnesota state. Together they form the experiment NOνA.

U.S. scientists have created the neutrino beam – which passes through the near and far detector, as well as all the matter in the earth’s crust that separates them – to give them the best chance of observing these particles and studying their strange behavior.

Neutrinos are like ghosts, invisible to the instruments of science, but very occasionally they collide with an atom of the fluid inside the detectors.

Whoever discovered the neutrinos

The existence of”neutrinos” was proposed by Wolfgang Pauli in 1930. This particle must not have been electrically charged, which is why Enrico Fermi called it”neutrino”, which means”the little neutral” in Italian.

Wolfgang Pauli interpreted that both mass and energy would be conserved if a hypothetical particle called”neutrino” participated in the disintegration by incorporating the lost quantities.

Unfortunately, this hypothetically predicted particle had to be without mass, charge, or strong interaction, so it could not be detected with the means of the time.

Pauli’s proposal was enriched by the Italian Enrico Fermi (Nobel Prize in 1938), who elaborated a formal theory on the presence of this particle which he called neutrino.

It was not foreseen that in the future, the recording of this phenomenon would revolutionize the thinking of particle physics and the conception of cosmology.

It was a quarter of a century later, with the implementation of nuclear power, which increased the emission of neutrinos on Earth, that American physicists Frederick Reines (Nobel Prize in 1995) and Clyde Cowan managed to detect their presence.

Neutrinos have mass

The Nobel Prize in Physics 2015 has been awarded to the Japanese Takaaki Kajita and the Canadian Arthur B. McDonald, for discovering the oscillations of neutrinos, which demonstrate that they are particles with mass.

The discovery led to the far-reaching conclusion that neutrinos, long considered to be massless, must have some mass, however small.

The winners of the 2015 Nobel Prize in Physics, Takaaki Kajita, and Arthur B. McDonald, solved the hitherto mysterious phenomenon of the disappearance of neutrinos emitted by the Sun on its way to Earth.

Once the emission of these particles in the nuclear reactions of our star was calculated, it was known that two-thirds of the calculated amount was missing from their arrival on the planet.

It was known that the Sun only produces neutrino electrons and the proposal was that at some point along the way these particles change charge.

To test the variation in qualities, colossal detectors installed in the bowels of the earth were used to protect the instrumentation so sensitive to cosmic radiation.

Two neutrino observatories were responsible for identifying this mutation: the Super-Kamiokande, built in 1996 at 1,000 meters below the surface in a zinc mine northwest of Tokyo, Japan, and the Sudbury Neutrino Observatory, located at a nickel mine in Ontario, Canada, which became operational in 1999. Both laboratories discovered the chameleon-like nature of neutrinos.

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