Not to be confused with neutron, neuron, or neutralino.
For other uses, see Neutrino (disambiguation).
Neutrino
The first use of a hydrogen bubble chamber to detect neutrinos, on 13 November 1970, at Argonne National Laboratory. Here a neutrino hits a proton in a hydrogen atom; the collision occurs at the point where three tracks emanate on the right of the photograph.
Composition
Elementary particle
Statistics
Fermionic
Family
Leptons, antileptons
Generation
First ( ν e), second ( ν μ), and third ( ν τ)
Interactions
Weak interaction and gravitation
Symbol
ν e , ν μ , ν τ , ν e , ν μ , ν τ
Particle
spin: ±+ 1 /2ħ,chirality: Left,weak isospin: + 1 /2,lepton nr.: +1, "flavour" in { e, μ, τ }
Antiparticle
spin: ±+ 1 /2ħ,chirality: Right,weak isospin: − 1 /2,lepton nr.: −1, "flavour" in { e, μ, τ }
Theorized
ν e, electron neutrino: Wolfgang Pauli (1930)
ν μ, muon neutrino: late 1940s
ν τ, tau neutrino: mid-1970s
Discovered
ν e: Clyde Cowan, Frederick Reines (1956)
ν μ: Leon Lederman, Melvin Schwartz and Jack Steinberger (1962)
ν τ: DONUT collaboration (2000)
Types
3 types: electron neutrino ( ν e), muon neutrino ( ν μ), and tau neutrino ( ν τ)
Mass
< 0.120 eV (< 2.14 × 10−37 kg), 95% confidence level, sum of 3 "flavours"[1]
Electric charge
0 e
Spin
1 /2ℏ
Weak isospin
LH: + 1 /2,RH: 0
Weak hypercharge
LH: −1,RH: 0
B − L
−1
X
−3
A neutrino (/njuːˈtriːnoʊ/new-TREE-noh; denoted by the Greek letter ν) is a fermion (an elementary particle with spin of 1 /2) that interacts only via the weak interaction and gravity.[2][3] The neutrino is so named because it is electrically neutral and because its rest mass is so small (-ino) that it was long thought to be zero. The rest mass of the neutrino is much smaller than that of the other known elementary particles (excluding massless particles).[1] The weak force has a very short range, the gravitational interaction is extremely weak due to the very small mass of the neutrino, and neutrinos do not participate in the electromagnetic interaction or the strong interaction.[4] Thus, neutrinos typically pass through normal matter unimpeded and undetected.[2][3]
Weak interactions create neutrinos in one of three leptonic flavors:
electron neutrino, ν e
muon neutrino, ν μ
tau neutrino, ν τ
Each flavor is associated with the correspondingly named charged lepton.[5] Although neutrinos were long believed to be massless, it is now known that there are three discrete neutrino masses with different tiny values (the smallest of which could even be zero[6]), but the three masses do not uniquely correspond to the three flavors: A neutrino created with a specific flavor is a specific mixture of all three mass states (a quantum superposition). Similar to some other neutral particles, neutrinos oscillate between different flavors in flight as a consequence. For example, an electron neutrino produced in a beta decay reaction may interact in a distant detector as a muon or tau neutrino.[7][8] The three mass values are not yet known as of 2024, but laboratory experiments and cosmological observations have determined the differences of their squares,[9] an upper limit on their sum (< 2.14×10−37 kg),[1][10] and an upper limit on the mass of the electron neutrino.[11]
For each neutrino, there also exists a corresponding antiparticle, called an antineutrino, which also has spin of 1 /2 and no electric charge. Antineutrinos are distinguished from neutrinos by having opposite-signed lepton number and weak isospin, and right-handed instead of left-handed chirality. To conserve total lepton number (in nuclear beta decay), electron neutrinos only appear together with positrons (anti-electrons) or electron-antineutrinos, whereas electron antineutrinos only appear with electrons or electron neutrinos.[12][13]
Neutrinos are created by various radioactive decays; the following list is not exhaustive, but includes some of those processes:
beta decay of atomic nuclei or hadrons
natural nuclear reactions such as those that take place in the core of a star
artificial nuclear reactions in nuclear reactors, nuclear bombs, or particle accelerators
during a supernova
during the spin-down of a neutron star
when cosmic rays or accelerated particle beams strike atoms
The majority of neutrinos which are detected about the Earth are from nuclear reactions inside the Sun. At the surface of the Earth, the flux is about 65 billion (6.5×1010) solar neutrinos, per second per square centimeter.[14][15] Neutrinos can be used for tomography of the interior of the Earth.[16][17]
^ abClose, Frank (2010). Neutrinos (softcover ed.). Oxford University Press. ISBN 978-0-199-69599-7.
^ abJayawardhana, Ray (2015). The Neutrino Hunters: The chase for the ghost particle and the secrets of the universe (softcover ed.). Oneworld Publications. ISBN 978-1-780-74647-0.
^Overbye, Dennis (15 April 2020). "Why the Big Bang produced something rather than nothing – How did matter gain the edge over antimatter in the early universe? Maybe, just maybe, neutrinos". The New York Times. Retrieved 16 April 2020.
^Nakamura, Kengo; Petcov, Serguey Todorov (2016). "Neutrino mass, mixing, and oscillations" (PDF). Chinese Physics C. 40: 100001.
^Boyle, Latham; Finn, Kiernan; Turok, Neil (2022). "The Big Bang, CPT, and neutrino dark matter". Annals of Physics. 438: 168767. arXiv:1803.08930. Bibcode:2022AnPhy.43868767B. doi:10.1016/j.aop.2022.168767. S2CID 119252778.
^Grossman, Yuval; Lipkin, Harry J. (1997). "Flavor oscillations from a spatially localized source — A simple general treatment". Physical Review D. 55 (5): 2760. arXiv:hep-ph/9607201. Bibcode:1997PhRvD..55.2760G. doi:10.1103/PhysRevD.55.2760. S2CID 9032778.
^Bilenky, Samoil M. (2016). "Neutrino oscillations: From a historical perspective to the present status". Nuclear Physics B. 908: 2–13. arXiv:1602.00170. Bibcode:2016NuPhB.908....2B. doi:10.1016/j.nuclphysb.2016.01.025. S2CID 119220135.
^Capozzi, Francesco; Lisi, Eligio; Marrone, Antonio; Montanino, Daniele; Palazzo, Antonio (2016). "Neutrino masses and mixings: Status of known and unknown 3ν parameters". Nuclear Physics B. 908: 218–234. arXiv:1601.07777. Bibcode:2016NuPhB.908..218C. doi:10.1016/j.nuclphysb.2016.02.016. S2CID 119292028.
^Olive, Keith A.; et al. (Particle Data Group) (2016). "Sum of neutrino masses" (PDF). Chinese Physics C. 40 (10): 100001. Bibcode:2016ChPhC..40j0001P. doi:10.1088/1674-1137/40/10/100001. S2CID 125766528.
^Cite error: The named reference KATRIN-2022-NatPhys was invoked but never defined (see the help page).
^"Ghostlike neutrinos". particlecentral.com. Scottsdale, AZ: Four Peaks Technologies. Retrieved 24 April 2016.
^"Conservation of lepton number". HyperPhysics / particles. Georgia State University. Retrieved 24 April 2016.
^
Armitage, Philip (2003). "Solar neutrinos" (PDF). JILA. Boulder, CO: University of Colorado. Retrieved 24 April 2016.
^
Bahcall, John N.; Serenelli, Aldo M.; Basu, Sarbani (2005). "New solar opacities, abundances, helioseismology, and neutrino fluxes". The Astrophysical Journal. 621 (1): L85–L88. arXiv:astro-ph/0412440. Bibcode:2005ApJ...621L..85B. doi:10.1086/428929. S2CID 1374022.
^
Millhouse, Margaret A.; Lipkin, David C. (2013). "Neutrino tomography". American Journal of Physics. 81 (9): 646–654. Bibcode:2013AmJPh..81..646M. doi:10.1119/1.4817314.
^
Aartsen, M. G.; et al. (The IceCube-PINGU Collaboration) (2014). The Precision IceCube Next Generation Upgrade (PINGU) (Report). Letter of Intent. arXiv:1401.2046.
A neutrino (/njuːˈtriːnoʊ/ new-TREE-noh; denoted by the Greek letter ν) is a fermion (an elementary particle with spin of 1 /2) that interacts only via...
A neutrino detector is a physics apparatus which is designed to study neutrinos. Because neutrinos only weakly interact with other particles of matter...
Neutrino oscillation is a quantum mechanical phenomenon in which a neutrino created with a specific lepton family number ("lepton flavor": electron, muon...
The IceCube Neutrino Observatory (or simply IceCube) is a neutrino observatory constructed at the Amundsen–Scott South Pole Station in Antarctica. The...
Sterile neutrinos (or inert neutrinos) are hypothetical particles (neutral leptons – neutrinos) that interact only via gravity and not via any of the other...
The electron neutrino ( ν e) is an elementary particle which has zero electric charge and a spin of 1⁄2. Together with the electron, it forms the first...
as neutrinos. Charged leptons can combine with other particles to form various composite particles such as atoms and positronium, while neutrinos rarely...
The tau neutrino or tauon neutrino is an elementary particle which has the symbol ν τ and zero electric charge. Together with the tau (τ), it forms the...
A solar neutrino is a neutrino originating from nuclear fusion in the Sun's core, and is the most common type of neutrino passing through any source observed...
The solar neutrino problem concerned a large discrepancy between the flux of solar neutrinos as predicted from the Sun's luminosity and as measured directly...
The muon neutrino is an elementary particle which has the symbol ν μ and zero electric charge. Together with the muon it forms the second generation of...
the microkernel architecture. This resulted in QNX Neutrino, released in 2001. Along with the Neutrino kernel, QNX Software Systems became a founding member...
emission of a positron with a neutrino in so-called positron emission. Neither the beta particle nor its associated (anti-)neutrino exist within the nucleus...
having zero electric charge. The two W bosons are verified mediators of neutrino absorption and emission. During these processes, the W± boson charge induces...
existence of quarks. Since then, proof of the top quark (1995), the tau neutrino (2000), and the Higgs boson (2012) have added further credence to the Standard...
Neutrino astronomy is the branch of astronomy that gathers information about astronomical objects by observing and studying neutrinos emitted by them...
Measurements of neutrino speed have been conducted as tests of special relativity and for the determination of the mass of neutrinos. Astronomical searches...
Supernova neutrinos are weakly interactive elementary particles produced during a core-collapse supernova explosion. A massive star collapses at the end...
down quarks which form protons and neutrons, and electrons and electron neutrinos. The three fundamental interactions known to be mediated by bosons are...
The Deep Underground Neutrino Experiment (DUNE) is a neutrino experiment under construction, with a near detector at Fermilab and a far detector at the...
neutrino background (CNB or CνB) is the universe's background particle radiation composed of neutrinos. They are sometimes known as relic neutrinos....
The Sudbury Neutrino Observatory (SNO) was a neutrino observatory located 2100 m underground in Vale's Creighton Mine in Sudbury, Ontario, Canada. The...
The Flying Neutrinos are an American jazz band from New Orleans. The band consists of Ingrid Lucia (vocals), Dan Levinson (saxophone), Matthew Munisteri...
In Big Bang cosmology, neutrino decoupling was the epoch at which neutrinos ceased interacting with other types of matter, and thereby ceased influencing...