Neutrinos are members of the same group as the most famous elementary particle, the electron, which drives every device we have ever read about. It is one of the so-called elementary particles, which means that it cannot consist of smaller parts, at least as far as we know.
Neutrinos are particles similar to the electron, but belonging to the lepton family of elementary particles. They are characterized by a lack of charge or mass that does not exist.
Neutrinos are the lightest known subatomic particles with a mass about 500,000 times less than that of an electron. They are one of the most abundant subatomic particles in the universe, emitted as part of the beta decay process that turns neutrons into protons, tens of billions hitting the fingernails every second. Neutrinos, however, tend to pass through matter undetected, making it difficult to measure it directly.
Some types of neutrinos have masses smaller than their charged partners. Experiments have shown that the mass of an electron neutrino is less than 0.002 percent of the mass of the electron and that the total mass of all three types of neutrinos is less than about 0.48 electrons per volt.
For many years, it seemed that neutrino masses had to be zero for compelling theoretical reasons. Recent experimental data, however, have shown that they may have masses that force theorists to revise the Standard Model of particle physics.
The discovery of the Higgs boson at the Large Hadron Collider was a great success in particle physics, but it is not enough to explain the hierarchy of the fermion masses and the tinyness of neutrino masses. Understanding neutrinos in physics is crucial to finding the relationship between neutrinos and other elementary particles and how this relationship relates to their relative masses.
Cosmology can also be used to limit the existence of non-standard neutrino-interaction mechanisms of mass production. For example, the effective number of neutrinos, a measure of energy density of relativistic species in the early universe, can be investigated for the existence or additional light-sterile mass-eigenstate physics (neutrino decoupling) and the existence of lepton asymmetries created by the early universe. These non-standard neutrinos are not the focus of this review, but we will address these aspects in the final section of the review.
Neutrinos are elusive subatomic particles produced by a variety of nuclear processes. Their name, which means “little neutral”, refers to the fact that they do not carry an electric charge.
Von the four fundamental forces in the universe, neutrinos interact only with two : the gravity and the weak force responsible for the radioactive decay of atoms. Although they have no mass, they orbit the cosmos at the speed of light.
A long-standing problem of particular interest is the so-called sun neutrino problem. One of the natural sources of neutrinos is the radioactive decay of primordial elements on Earth, which produces a large flow of low-energy electrons and anti-neutrinos. Calculations show that about 2 percent of the solar energy is carried away by neutrons that arise in fusion reactions.
Neutrinos are subatomic particles that resemble electrons but have no electrical charge and a low mass near zero. Since they hardly interact with matter, they are very difficult to detect. They are most commonly detected when muon neutrinos, generated by cosmic rays, hit Earth’s atmosphere.
Every time an atomic nucleus comes together in the sun or breaks apart in a nuclear reactor, it produces neutrinos. Bananas also emit neutrino, but they come from the natural radioactivity of potassium in the fruit. Nuclear power treats electrons and neutrons as part of the strong nuclear force, while they are involved in the weak nuclear force.
Scientists today are trying to determine what the mass of neutrinos is, how they interact with matter and whether they are their own antiparticles (particles of the same mass, but with electrical and magnetic properties) or not.
In 2002, the Sudbury Neutrino Observatory in Ontario, Canada, discovered the first direct evidence that electron neutrinos emitted in the Sun’s core by nuclear reactions can change their nature as they pass through the Sun. Such neutrino oscillations are possible when one or more neutrino types are of low mass.
Neutrinos exist with a corresponding antiparticle called antineutrino, which rotates 1 / 2 as fast and has no electrical charge. Antineutrons can be distinguished from neutrinos by showing the sign of the lepton and the number of manual or right-handed chirality. A neutrino and its opposite, the antineurino, are right-handed versions of the same particle and can marry in mass.
In this scenario, the neutrino would derive its mass from the interaction between its antineutrino. For this to work, theorists would have to invent a unique form of the Higgs boson that interacts with neutrinos. This would mean that the neutrinos (also called marjorana fermions) that occur as particles and antiparticles would be identical.
Collisions with high-energy protons can produce neutrinos, and cosmic ray sources can produce them. Neutrinos can also interact electrically to produce charged particles, generating measurable signals in transparent media. IceCube measured light produced when secondary particles generated by neutrino energies interact with the South Pole ice thousands to billions of times larger than the Sun’s fusion reaction force.
A neutrino (referred to by the Greek letter fermion) is an elementary particle with a spin of 1 / 2 that interacts with the weak interaction of gravity. The residual mass of neutrinos is smaller than that of all other known elementary particles, without massless particles. Neutrinos produce specific flavors associated with specific quantum superimpositions of three mass states.
As they traverse the distance between the Sun and our planet, neutrinos oscillate between three types, and early experiments designed to find a taste missed two thirds of their total number. For example, electron neutrino produced in beta decay reactions interact with distant detectors, as do muon and tau neutrins.