Neutrino: Difference between revisions

| name = Neutrino / Antineutrino

| particle = {{nobr|spin: {{small|{{sfrac|±| 1 |2}}}}{{math|''ħ''}},}} {{nobr|[[Chirality (physics)|chirality]]: '''L'''eft,}} {{nobr|[[weak isospin]]: +{{small|{{sfrac| 1 |2}}}},}} {{nobr|[[lepton number|lepton nr.]]: +1}}, {{nobr|[[Flavour (particle physics)|"flavourflavor"]] in {{mset| {{math|e, μ, τ}} }} }}

| antiparticle = {{nobr|spin: {{small|{{sfrac|±| 1 |2}}}}{{math|''ħ''}},}} {{nobr|[[Chirality (physics)|chirality]]: '''R'''ight,}} {{nobr|[[weak isospin]]: −{{small|{{sfrac| 1 |2}}}},}} {{nobr|[[lepton number|lepton nr.]]: −1}}, {{nobr| [[Flavour (particle physics)|"flavourflavor"]] in {{mset| {{overline|{{math|e}}}}, {{overline|{{math|μ}}}}, {{overline|{{math|τ}}}} }} }}

| mass = {{nobr|< 0.120 eV}} ({{nobr|< 2.14 × {{10^|−37}} kg}}), 95% confidence level, sum of 3&nbsp;[[Flavour (particle physics)|"flavoursflavors"]]<ref name=Mertens-2016-mν>

|first1=Susanne |last1=Mertens

|year=2016

|title=Direct neutrino mass experiments

|journal=[[Journal of Physics: Conference Series]]

|volume=718 |issue=2 |page=022013

|arxiv=1605.01579 |bibcode=2016JPhCS.718b2013M

|doi=10.1088/1742-6596/718/2/022013 |s2cid=56355240

}}</ref>

| weak_isospin = {{nobr|[[Chirality (physics)|LH]]: +{{sfrac| 1 |2}},}} {{nobr|[[Chirality (physics)|RH]]: 0}}

| weak_hypercharge= {{nobr|[[Chirality (physics)|LH]]: −1,}} {{nobr|[[Chirality (physics)|RH]]: 0}}

Each flavor is associated with the correspondingly named charged [[lepton]].<ref>{{cite journal |last1=Nakamura |first1=Kengo |last2=Petcov |first2=Serguey Todorov |year=2016 |title=Neutrino mass, mixing, and oscillations |journal=[[Chinese Physics C]] |volume=40 |page=100001 |url=http://pdg.lbl.gov/2016/reviews/rpp2016-rev-neutrino-mixing.pdf}}</ref> 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<ref>{{cite journal |last1 = Boyle |first1 = Latham |last2 = Finn |first2 = Kiernan |last3 = Turok |first3 = Neil |year = 2022 |title = The Big Bang, CPT, and neutrino dark matter |journal = Annals of Physics |volume = 438 |page = 168767 |doi = 10.1016/j.aop.2022.168767 |arxiv = 1803.08930 |bibcode = 2022AnPhy.43868767B |s2cid = 119252778}}</ref>), 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 [[neutral particle oscillation|other neutral particles]], [[Neutrino oscillation|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.<ref name=Grossman-Lipkin-1997>{{cite journal |last1=Grossman |first1=Yuval |last2=Lipkin |first2=Harry J. |author2-link=Harry J. Lipkin |year=1997 |title=Flavor oscillations from a spatially localized source — A simple general treatment |journal=[[Physical Review|Physical Review D]] |volume=55 |issue=5 |page=2760 |arxiv=hep-ph/9607201 |bibcode=1997PhRvD..55.2760G |doi=10.1103/PhysRevD.55.2760 |s2cid=9032778}}</ref><ref name=Bilenky-2016-ν-osc>{{cite journal |first=Samoil M. |last=Bilenky |year=2016 |arxiv=1602.00170 |bibcode=2016NuPhB.908....2B |doi=10.1016/j.nuclphysb.2016.01.025 |title=Neutrino oscillations: From a historical perspective to the present status |journal=[[Nuclear Physics (journal)|Nuclear Physics B]] |volume=908 |pages=2–13 |s2cid=119220135}}</ref> The three mass values are not yet known as of 20222024, but laboratory experiments and [[Cosmology|cosmological]] observations have determined the differences of their squares,<ref name=Capozzi-Lisi-Marrone-etal-2016>{{cite journal |last1=Capozzi |first1=Francesco |last2=Lisi |first2=Eligio |last3=Marrone |first3=Antonio |last4=Montanino |first4=Daniele |last5=Palazzo |first5=Antonio |year=2016 |title=Neutrino masses and mixings: Status of known and unknown 3ν parameters |journal=Nuclear Physics B |volume=908 |pages=218–234 |arxiv=1601.07777 |bibcode=2016NuPhB.908..218C |doi=10.1016/j.nuclphysb.2016.02.016 |s2cid=119292028}}</ref> an upper limit on their sum (<&nbsp;{{val|2.14|e=-37|u=kg}}),<ref name=Mertens-2016-mν/><ref name=Olive-PDG-2016-Σmν>{{cite journal |last1=Olive |first1=Keith A. |author-link=Keith Olive |collaboration=[[Particle Data Group]] |year=2016 |title=Sum of neutrino masses |journal=Chinese Physics C |volume=40 |issue=10 |page=100001 |bibcode=2016ChPhC..40j0001P |doi=10.1088/1674-1137/40/10/100001 |s2cid=125766528 |url=http://pdg.lbl.gov/2016/reviews/rpp2016-rev-sum-neutrino-masses.pdf}}</ref> and an upper limit on the mass of the electron neutrino.<ref name=KATRIN-2022-NatPhys/>

For each neutrino, there also exists a corresponding [[antiparticle]], called an [[#Antineutrinos|''antineutrino'']], which also has spin of {{sfrac| 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 (physics)|chirality]]. To conserve total lepton number (in nuclear [[beta decay]]), electron neutrinos only appear together with [[positron]]s (anti-electrons) or electron-antineutrinos, whereas electron antineutrinos only appear with electrons or electron neutrinos.<ref name=FourPeaksAZ-ghostν>{{cite web |title=Ghostlike neutrinos |website=particlecentral.com |publisher=Four Peaks Technologies |location=Scottsdale, AZ |url=http://www.particlecentral.com/neutrinos_page.html |access-date=24 April 2016}}</ref><ref name=HypPhys-GSU-consℓ>{{cite web |title=Conservation of lepton number |series=HyperPhysics / particles |publisher=Georgia State University |url=http://hyperphysics.phy-astr.gsu.edu/hbase/particles/parint.html#c3 |access-date=24 April 2016}}</ref>

|last1=Bahcall |first1=John N. |author-link1=John N. Bahcall

|last3=Basu |first3=Sarbani |author-link3=Sarbani Basu

|volume=621 |issue=1 |pages=L85–L88

|s2cid=1374022 |arxiv=astro-ph/0412440

|bibcode=2005ApJ...621L..85B |doi=10.1086/428929

|first2=David C. |last2=Lipkin

</ref><ref name="PINGU-2014-LoIntt">

== History ==

=== Pauli's proposal ===

was postulated first by [[Wolfgang Pauli]] in 1930 to explain how [[beta decay]] could conserve [[conservation of energy|energy]], [[conservation of momentum|momentum]], and [[conservation of angular momentum|angular momentum]] ([[Spin (physics)|spin]]). In contrast to [[Niels Bohr]], who proposed a statistical version of the conservation laws to explain the observed [[Beta decay#Neutrinos|continuous energy spectra in beta decay]], Pauli hypothesized an undetected particle that he called a "neutron", using the same ''-on'' ending employed for naming both the [[proton]] and the [[electron]]. He considered that the new particle was emitted from the nucleus together with the electron or beta particle in the process of beta decay and had a mass similar to the electron.<ref name=Brown-1978-idea-ν>

|bibcode=1978PhT....31i..23B |doi=10.1063/1.2995181

[[Niels Bohr]] was notably opposed to this interpretation of beta decay – hedecay—he was ready to accept that energy, momentum, and angular momentum were not conserved quantities at the atomic level.

|last=Amaldi |first=Edoardo |author-link=Edoardo Amaldi

|volume=111 |issue=1–4 |page=306

|bibcode=1984PhR...111....1A |doi=10.1016/0370-1573(84)90214-X

: {{math| {{SubatomicParticle|Neutron0}} → {{SubatomicParticle|Proton+}} + {{SubatomicParticle|Electron-}} + {{SubatomicParticle|Electron antineutrino}} }}

|journal=[[Zeitschrift für Physik A]] |language=de

|last1=Fermi |first1=Enrico |author1-link=Enrico Fermi

|bibcode=1968AmJPh..36.1150W |doi=10.1119/1.1974382

=== Direct detection ===

|last1=Cowan |first1=Clyde L. Jr. |author1-link=Clyde Cowan

|last2=Reines |first2=Frederick |author2-link=Frederick Reines

|last4=Kruse |first4=Herald W.

|last5=McGuire |first5=Austin D.

|volume=124 |issue=3212 |pages=103–104

|doi=10.1126/science.124.3212.103 |pmid=17796274

|last=Winter |first=Klaus

In this experiment, now known as the [[Cowan–Reines neutrino experiment]], antineutrinos created in a nuclear reactor by beta decay reacted with protons to produce [[neutron]]s and [[positron]]spositrons:

|last2=Tegen |first2=Rudolph

=== Neutrino flavor{{ <span class="anchor|" id="Neutrino_flavors_anchor}}"></span> ===

The antineutrino [[Cowan–Reines neutrino experiment|discovered by [[Clyde Cowan]] and [[Frederick Reines]] was the antiparticle of the [[electron neutrino]].

In 1962, [[Leon M. Lederman|Lederman]], [[Melvin Schwartz|Schwartz]], and [[Jack Steinberger|Steinberger]] showed that more than one type of neutrino exists by first detecting interactions of the [[muon]] neutrino (already hypothesised with the name ''neutretto''),<ref>

When the third type of [[lepton]], the [[tau (particle)|tau]], was discovered in 1975 at the [[Stanford Linear Accelerator Center]], it was also expected to have an associated neutrino (the tau neutrino). The first evidence for this third neutrino type came from the observation of missing energy and momentum in tau decays analogous to the beta decay leading to the discovery of the electron neutrino. The first detection of tau neutrino interactions was announced in 2000 by the [[DONUT|DONUT collaboration]] at [[Fermilab]]; its existence had already been inferred by both theoretical consistency and experimental data from the [[Large Electron–Positron Collider]].<ref>

=== Solar neutrino problem ===

In the 1960s, the now-famous [[Homestake experiment]] made the first measurement of the flux of electron neutrinos arriving from the core of the Sun and found a value that was between one third and one half the number predicted by the [[Standard Solar Model]]. This discrepancy, which became known as the [[solar neutrino problem]], remained unresolved for some thirty years, while possible problems with both the experiment and the solar model were investigated, but none could be found. Eventually, it was realized that both were actually correct and that the discrepancy between them was due to neutrinos being more complex than was previously assumed. It was postulated that the three neutrinos had nonzero and slightly different masses, and could therefore oscillate into undetectable flavors on their flight to the Earth. This hypothesis was investigated by a new series of experiments, thereby opening a new major field of research that still continues. Eventual confirmation of the phenomenon of neutrino oscillation led to two Nobel prizes, one to [[Raymond Davis, Jr.|R. Davis]], who conceived and led the Homestake experiment and [[Masatoshi Koshiba]] of Kamiokande, whose work confirmed it, and one to [[Takaaki Kajita]] of Super-Kamiokande and [[Arthur B. McDonald|A.B. McDonald]] of [[Sudbury Neutrino Observatory|SNO]] for their joint experiment, which confirmed the existence of all three neutrino flavors and found no deficit.<ref name=CERN-2001-12-04-SNO/>

=== Oscillation ===

|last4=Valle |first4=José W.F. |author-link4=José W. F. Valle

=== Cosmic neutrinos ===

; Cosmic neutrino background (Big Bang originated) :

; Diffuse supernova neutrino background (Supernova originated) :

[[Raymond Davis, Jr.|R. Davis]] and [[Masatoshi Koshiba|M. Koshiba]] were jointly awarded the 2002 [[Nobel Prize in Physics]]. Both conducted pioneering work on [[solar neutrino]] detection, and Koshiba's work also resulted in the first real-time observation of neutrinos from the [[SN 1987A]] supernova in the nearby [[Large Magellanic Cloud]]. These efforts marked the beginning of [[neutrino astronomy]].<ref name=Pagliarl-Vissani-etal-2009>

|last1=Pagliaroli |first1=Giulia

|last2=Vissani |first2=Francesco

|last3=Costantini |first3=Maria Laura

|last4=Ianni |first4=Aldo

|volume=31 |issue=3 |pages=163–176

|arxiv=0810.0466 |doi=10.1016/j.astropartphys.2008.12.010

|bibcode=2009APh....31..163P |s2cid=119089069

== Properties and reactions ==

Neutrinos have half-integer [[Spin (physics)|spin]] ({{sfrac| 1 |2}}{{math|''ħ''}}); therefore they are [[fermion]]s. Neutrinos are [[lepton]]sleptons. They have only been observed to interact through the [[weak nuclear force|weak force]], although it is assumed that they also interact gravitationally. Since they have non-zero mass, theoretical considerations permit neutrinos to interact magnetically, but do not require them to. As yet there is no experimental evidence for a non-zero [[magnetic moment]] in neutrinos.

=== Flavor, mass, and their mixing ===

Weak interactions create neutrinos in one of three leptonic [[Flavor (particle physics)|flavors]]: [[electron neutrino]]sneutrinos ({{math|{{SubatomicParticle|Electron neutrino}}}}), [[muon neutrino]]sneutrinos ({{math|{{SubatomicParticle|Muon neutrino}}}}), or [[tau neutrino]]s ({{math|{{SubatomicParticle|Tau neutrino}}}}), associated with the corresponding charged leptons, the [[electron]] ({{math|{{SubatomicParticle|Electron}}}}), [[muon]] ({{math|{{SubatomicParticle|Muon}}}}), and [[tau (particle)|tau]] ({{math|{{SubatomicParticle|Tau}}}}), respectively.<ref name=Nakamura-Petcov-PDG-2016-νmix>

|last1=Nakamura |first1=Kengo

|last2=Petcov |first2=Serguey Todorov

More formally, neutrino flavor [[Eigenvalues and eigenvectors|eigenstates]] (creation and annihilation combinations) are not the same as the neutrino mass eigenstates (simply labeled "1", "2", and "3"). As of 20162024, it is not known which of these three is the heaviest. The [[neutrino mass hierarchy]] consists of two possible configurations. In analogy with the mass hierarchy of the charged leptons, the configuration with mass&nbsp;2 being lighter than mass&nbsp;3 is conventionally called the "normal hierarchy", while in the "inverted hierarchy", the opposite would hold. Several major experimental efforts are underway to help establish which is correct.<ref name=hierarchy>

|last1=Giunti |first1=Carlo

|last2=Studenikin |first2=Alexander I.

|volume=87 |issue=2 |pages=531–591

|bibcode=2015RvMP...87..531G |s2cid=119261485

=== Flavor oscillations ===

Neutrinos [[Neutrino oscillation|oscillate]] between different flavors in flight. For example, an electron neutrino produced in a [[beta decay]] reaction may interact in a distant detector as a muon or tau neutrino, as defined by the flavor of the charged lepton produced in the detector. This oscillation occurs because the three mass state components of the produced flavor travel at slightly different speeds, so that their quantum mechanical [[wave packet]]s develop relative [[Phase (waves)#phase shift|phase shift]]s that change how they combine to produce a varying superposition of three flavors. Each flavor component thereby oscillates as the neutrino travels, with the flavors varying in relative strengths. The relative flavor proportions when the neutrino interacts represent the relative probabilities for that flavor of interaction to produce the corresponding flavor of charged lepton.<ref name=Grossman-Lipkin-1997/><ref name=Bilenky-2016-ν-osc/>

|last1=Kostelecký |first1=V. Alan |author-link1=Alan Kostelecky

|last2=Mewes |first2=Matthew

|volume=69 |issue=1 |page=016005

|hdl=2022/18691 |s2cid=119024343

|arxiv=hep-ph/0309025 |bibcode=2004PhRvD..69a6005A

=== Mikheyev–Smirnov–Wolfenstein effect ===

Neutrinos traveling through matter, in general, undergo a process analogous to [[Speed of light#In a medium|light traveling through a transparent material]]. This process is not directly observable because it does not produce [[ionizing radiation]], but gives rise to the [[MSWMikheyev–Smirnov–Wolfenstein effect]]. Only a small fraction of the neutrino's energy is transferred to the material.<ref>

|url=https://www.nobelprize.org/nobel_prizesuploads/physics2017/laureates/201509/advanced-physicsprize2015.pdf

=== Antineutrinos ===

For each neutrino, there also exists a corresponding [[antiparticle]], called an ''antineutrino'', which also has no electric charge and half-integer spin. They are distinguished from the neutrinos by having opposite signs of [[lepton number]] and opposite [[Chirality (physics)|chirality]] (and consequently opposite-sign [[weak isospin]]). As of 2016, no evidence has been found for any other difference.

Antineutrinos are produced in nuclear [[beta decay]] together with a [[beta particle]] (in beta decay a neutron decays into a proton, electron, and antineutrino). All antineutrinos observed thus far had right-handed [[helicity (particle physics)|helicity]] (i.e., only one of the two possible spin states has ever been seen), while neutrinos were all left-handed.{{efn|Nevertheless, because neutrinos have mass, their helicity is [[Frame of reference|frame]]-dependent, so particle physicists have fallen back on the frame-independent property of [[chirality]] that is closely related to helicity, and for practical purposes the same as the helicity of the ultra-relativistic neutrinos that can be observed in detectors.}}

|archive-date=2007-11-12
}}

=== Majorana mass ===

Because antineutrinos and neutrinos are neutral particles, it is possible that they are the same particle. Rather than conventional [[Dirac fermion]]s, neutral particles can be another type of spin&nbsp;{{sfrac| 1 |2}} particle called ''[[Majorana particle]]s'' or ''Majorons'', named after the Italian physicist [[Ettore Majorana]] who first proposed the concept. For the case of neutrinos this theory has gained popularity as it can be used, in combination with the [[seesaw mechanism]], to explain why neutrino masses are so small compared to those of the other elementary particles, such as electrons or quarks. Majorana neutrinos would have the property that the neutrino and antineutrino could be distinguished only by [[chirality (physics)|chirality]]; what experiments observe as a difference between the neutrino and antineutrino could simply be due to one particle with two possible chiralities.

{{As of|2019}}, it is not known whether neutrinos are [[Majorana particlefermion|Majorana]] or [[Dirac fermion|Dirac]] particles. It is possible to test this property experimentally. For example, if neutrinos are indeed Majorana particles, then lepton-number violating processes such as [[neutrinoless double beta decay|neutrinoless double-beta decay]] would be allowed, while they would not if neutrinos are [[Dirac fermion|Dirac]] particles. Several experiments have been and are being conducted to search for this process, e.g. [[Germanium Detector Array|GERDA]],<ref name=Giunti-Kim-2007-Fundm-νν/> [[Enriched Xenon Observatory|EXO]],<ref>

|last1=Andringa |first1=Sofia |last2=Arushanova |first2=Evelina

|last3=Asahi |first3=Shigeo |last4=Askins |first4=Morgan

|last5=Auty |first5=David John |last6=Back |first6=Asheley R.

|last7=Barnard |first7=Zachariah |last8=Barros |first8=Nuno

|last9=Beier |first9=Eugene W. |author-link9=Eugene W. Beier

|doi-access=free
}}

</ref> and [[CUORE]].<ref>

|volume=115 |issue=10 |page=102502

|doi=10.1103/PhysRevLett.115.102502 |pmid=26382673

|bibcode=2015PhRvL.115j2502A |arxiv=1504.02454 |s2cid=30807808

|last1=Long |first1=Andrew J.

|last2=Lunardini |first2=Cecilia |author2-link=Cecilia Lunardini

|doi=10.1088/1475-7516/2014/08/038 |arxiv=1405.7654

|bibcode=2014JCAP...08..038L |s2cid=119102568

=== Nuclear reactions ===

|access-date=2008-06-04 |quote=The detector consists of a 12&nbsp;meter diameter acrylic sphere containing 1000 tonnes of heavy water ... [Solar neutrinos] are detected at SNO via the charged current process of electron neutrinos interacting with deuterons to produce two protons and an electron.

It is very hard to uniquely identify neutrino interactions among the natural background of radioactivity. For this reason, in early experiments a special reaction channel was chosen to facilitate the identification: the interaction of an antineutrino with one of the hydrogen nuclei in the water molecules. A hydrogen nucleus is a single proton, so simultaneous nuclear interactions, which would occur within a heavier nucleus, don'tdo not need to be considered for the detection experiment. Within a cubic metremeter of water placed right outside a nuclear reactor, only relatively few such interactions can be recorded, but the setup is now used for measuring the reactor's plutonium production rate.

=== Induced fission and other disintegration events ===

Very much like [[neutron]]sneutrons do in [[nuclear reactor]]s, neutrinos can induce [[fission reaction]]s within heavy [[atomic nucleus|nuclei]].<ref name=Kolbe-Langanke-Fuller-2004/> So far, this reaction has not been measured in a laboratory, but is predicted to happen within stars and supernovae. The process affects the [[Abundance of the chemical elements|abundance of isotopes]] seen in the [[universe]].<ref name=Kelić-Zinner-Kolbe-etal-2005/> Neutrino-induced disintegration of [[deuterium]] nuclei has been observed in the [[Sudbury Neutrino Observatory]], which uses a [[heavy water]] detector.<ref>{{cite journal |last1=Bellerive |first1=A |last2=Klein |first2=J.R. |last3=McDonald |first3=A.B. |last4=Noble |first4=A.J. |last5=Poon |first5=A.W.P. |title=The Sudbury Neutrino Observatory |journal=Nuclear Physics B |date=July 2016 |volume=908 |issue= |pages=30–51 |doi=10.1016/j.nuclphysb.2016.04.035 |arxiv=1602.02469 |bibcode=2016NuPhB.908...30B |s2cid=117005142 |url=https://www.sciencedirect.com/science/article/pii/S0550321316300736 |access-date=Nov 20, 2022}}</ref>

=== Types ===

There are three known types (''[[flavor (particle physics)|flavors]]'') of neutrinos: electron neutrino {{math|{{SubatomicParticle|electron neutrino}}}}, muon neutrino {{math|{{SubatomicParticle|muon neutrino}}}}, and tau neutrino {{math|{{SubatomicParticle|tau neutrino}}}}, named after their partner [[lepton]]sleptons in the [[Standard Model]] (see table at right). The current best measurement of the number of neutrino types comes from observing the decay of the [[W and Z bosons|Z boson]]. This particle can decay into any light neutrino and its antineutrino, and the more available types of light neutrinos,{{efn|

== Research ==

* evidence of physics which might break the [[Standard Model]] of [[particle physics]], such as [[neutrinoless double beta decay]], which would be evidence for violation of lepton number conservation.

=== Detectors near artificial neutrino sources ===

|date=2018-06-12 |lang=de

=== Gravitational effects ===

The three known neutrino flavors are the only candidates for [[dark matter]] that are experimentally established [[elementary particle]]s – specificallyparticles—specifically, they would be [[hot dark matter]]. However, the currently known neutrino types seem to be essentially ruled out as a substantial proportion of dark matter, based on observations of the [[cosmic microwave background]]. It still seems plausible that heavier, sterile neutrinos might compose [[warm dark matter]], if they exist.<ref>

|last2=Widrow |first2=Lawrence M.

|volume=72 |number=17 |pages=17–20

=== Sterile neutrino searches ===

Other efforts search for evidence of a [[sterile neutrino]] – a—a fourth neutrino flavor that would not interact with matter like the three known neutrino flavors.<ref>

|first1=Georgia |last1=Karagiorgi |first2=Alexis |last2=Aguilar-Arevalo

|first3=Janet M. |last3=Conrad |author-link3=Janet Conrad

|first4=Michael H. |last4=Shaevitz |first5=Kerry |last5=Whisnant

|first6=Michel |last6=Sorel |first7=Vernon |last7=Barger

|volume=75 |issue=1 |page=013011

|first=Mark |last=Alpert

|archive-date=2017-03-29 }}

|last1=Mueller |first1=Thomas Alexandre |last2=Lhuillier |first2=David

|last3=Fallot |first3=Muriel |last4=Letourneau |first4=Alain

|last5=Cormon |first5=Sandrine |last6=Fechner |first6=Maximilien

|last7=Giot |first7=Lydie |last8=Lasserre |first8=Thierry

|last9=Martino |first9=J. Rodriguez |last10=Mention |first10=Guillaume

|last11=Porta |first11=Amanda |last12=Yermia |first12=Frédéric

|volume=83 |issue=5 |page=054615

|arxiv=1101.2663 |bibcode=2011PhRvC..83e4615M

|s2cid=118381633 |doi=10.1103/PhysRevC.83.054615

|last1=Mention |first1=Guillaume |last2=Fechner |first2=Maximilien

|last3=Lasserre |first3=Thierry |last4=Mueller |first4=Thomas Alexandre

|last5=Lhuillier |first5=David |last6=Cribier |first6=Michel

|volume=83 |issue=7 |page=073006

|s2cid=14401655 |bibcode=2011PhRvD..83g3006M

|arxiv=1101.2755 |doi=10.1103/PhysRevD.83.073006

|last1=Schoppmann |first1=Stefan

|volume=7 |issue=10 |page=360

|arxiv=2109.13541 |doi=10.3390/universe7100360

|bibcode=2021Univ....7..360S

}}

According to an analysis published in 2010, data from the [[Wilkinson Microwave Anisotropy Probe]] of the [[Cosmic microwave background radiation|cosmic background radiation]] is compatible with either three or four types of neutrinos.<ref>{{cite magazine |first=Ron |last=Cowen |date=2 February 2010 |title=New look at Big Bang radiation refines age of universe |url=https://www.wired.com/2010/02/nasa-wmap-universe-age/ |magazine=[[Wired (magazine)|Wired]] |access-date=2016-11-01 }}</ref>

=== Neutrinoless double-beta decay searches ===

=== Cosmic ray neutrinos ===

=== Speed ===

Also, there are some [[Lorentz violationcovariance|Lorentz-violating]] variants of [[quantum gravity]] which might allow faster-than-light neutrinos.{{citation needed|date=August 2021}} A comprehensive framework for Lorentz violations is the [[Standard-Model Extension]] (SME).

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|last17=Bernstein |first17=R.H. |last18=Bhattacharya |first18=D.

|last19=Bishai |first19=M. |last20=Blake |first20=A.

|last21=Bock |first21=B. |last22=Bock |first22=G.J.

|last23=Boehm |first23=J. |last24=Boehnlein |first24=D.J.

|last25=Bogert |first25=D. |last26=Border |first26=P.M.

|last27=Bower |first27=C. |last28=Buckley-Geer |first28=E.

|last29=Cabrera |first29=A. |last30=Chapman |first30=J.D.

|volume=76 |issue=7 |page=072005

|arxiv=0706.0437 |bibcode=2007PhRvD..76g2005A

|s2cid=14358300 |doi=10.1103/PhysRevD.76.072005

A similar observation was made, on a much larger scale, with [[supernova 1987A]] ([[SN 1987A]]). Antineutrinos with an energy of 10&nbsp;MeV from the supernova were detected within a time window that was consistent with the speed of light for the neutrinos. So far, all measurements of neutrino speed have been consistent with the speed of light.<ref>

|first1=Andrew |last1=Cohen

|s2cid=56198539

}}

==== Superluminal neutrino glitch ====

In September&nbsp;2011, the [[OPERA experiment|OPERA collaboration]] released calculations showing velocities of 17&nbsp;GeV and 28&nbsp;GeV neutrinos exceeding the speed of light in their experiments. In November&nbsp;2011, OPERA repeated its experiment with changes so that the speed could be determined individually for each detected neutrino. The results showed the same faster-than-light speed. In February&nbsp;2012, reports came out that the results may have been caused by a loose fiber optic cable attached to one of the atomic clocks which measured the departure and arrival times of the neutrinos. An independent recreation of the experiment in the same laboratory by [[ICARUS (experiment)|ICARUS]] found no discernible difference between the speed of a neutrino and the speed of light.<ref name=Antonlo-Aprli-Baibusnv-etal-2012/>

=== Mass <span type="anchor" id="neutrino_mass_anchor">Mass</span> ===

[[File:NeutrinoMassTimeline2022.webp|thumb|left|Timeline of neutrino mass measurements by different experiments.<ref name=KATRIN-2022-NatPhys/>]]

The [[Standard Model]] of particle physics assumed that neutrinos are massless.<ref>

</ref> The experimentally established phenomenon of neutrino oscillation, which mixes neutrino flavourflavor states with neutrino mass states (analogously to [[Cabibbo–Kobayashi–Maskawa matrix|CKM mixing]]), requires neutrinos to have nonzero masses.<ref>

TheA strongesthard upper limit on the masses of neutrinos comes from [[physical cosmology|cosmology]]: the [[Big Bang]] model predicts that there is a fixed ratio between the number of neutrinos and the number of [[photon]]s in the [[cosmic microwave background radiation|cosmic microwave background]]. If the total energymass of all three types of neutrinos exceeded an average of {{val|50|ul=eV/c2}} per neutrino, there would be so much mass in the universe that it would collapse.<ref>

|doi=10.1016/0370-2693(79)90039-X |bibcode=1979PhLB...87..144H

|volume=2006 |issue=6 |page=019

|arxiv=astro-ph/0602155 |bibcode=2006JCAP...06..019G

|s2cid=119535760 |doi=10.1088/1475-7516/2006/06/019

|volume=641 |issue=A6

|arxiv=1807.06209 |doi=10.1051/0004-6361/201833910

|bibcode=2020A&A...641A...6P

}}</ref> A 2021 reanalysis that adds redshift space distortion measurements from the SDSS-IV eBOSS survey gets an even tighter upper limit of {{val|0.09|u=eV/c2}}.<ref>

|last2=Gariazzo |first2=Stefano

|last3=Mena |first3=Olga

|volume=104

}}</ref> However, several ground-based telescopes with similarly sized error bars as Planck prefer higher values for the neutrino mass sum, indicating some tension in the data sets.<ref>

|last2=Melchiorri |first2=Alessandro

|journal=The Astrophysical Journal Letters

}}</ref>

The Nobel prize in Physics 2015 was awarded to [[Takaaki Kajita]] and [[Arthur B. McDonald]] for their experimental discovery of neutrino oscillations, which demonstrates that neutrinos have mass.<ref>

}}</ref><ref>

</ref> Since June&nbsp;2018 the [[KATRIN]] experiment searches for a mass between {{val|0.2|u=eV/c2}} and {{val|2|u=eV/c2}} in tritium decays.<ref name=KATRIN-2018-06-12-pr/> The February 2022 upper limit is ''m''_ν < {{val|0.8|u=eV/c2}} at 90% CL in combination with a previous campaign by KATRIN from 2019.<ref name="KATRIN-2022-NatPhys">

|journal=[[Nature (journal)|Nature]] |language=en

|doi=10.1038/d41586-022-00430-x |pmid=35165410 |s2cid=246827702

On 31 May 2010, [[OPERA experiment|OPERA]] researchers observed the first [[tau neutrino]] candidate event in a [[muon neutrino]] beam, the first time this transformation in neutrinos had been observed, providing further evidence that they have mass.<ref name=Agafnva-Aleksndrv-Altinok-etal-2010/>

If the neutrino is a [[Majorana fermion|Majorana particle]], the mass may be calculated by finding the [[half-life]] of [[DoubleNeutrinoless double beta decay|neutrinoless double-beta decay]] of certain nuclei. The current lowest upper limit on the Majorana mass of the neutrino has been set by [[KamLAND]]-Zen: {{val|0.060|–|0.161|u=eV/c2}}.<ref>

|last1=Gando |first1=Azusa

|s2cid=204937469
}}</ref>

=== Chirality ===

|last1=Goldhaber |first1=Maurice |author1-link=Maurice Goldhaber

|last2=Grodzins |first2=Lee |author2-link=Lee Grodzins

|last3=Sunyar |first3=Andrew W.

|volume=109 |issue=3 |pages=1015–1017

|doi=10.1103/PhysRev.109.1015 |doi-access=free

</ref> In the massless limit, that means that only one of two possible [[chirality (physics)|chiralities]] is observed for either particle. These are the only chiralities included in the [[Standard Model]] of particle interactions.

|last=Kayser |first=Boris J. |author-link=Boris Kayser

|access-date=2007-11-25
}}

|last2=Giunti |first2=Carlo

|volume=16 |issue=24 |pages=3931–3949

|arxiv=hep-ph/0102320 |bibcode=2001IJMPA..16.3931B

|s2cid=18544616 |doi=10.1142/S0217751X01004967

=== GSI anomaly ===

The rates of [[Weak interaction|weak]] decay of two radioactive species with half lives of about 40&nbsp;seconds and 200&nbsp;seconds were found to have a significant oscillatory [[modulation]], with a period of about 7&nbsp;seconds.<ref name=Kienle-Bosch-Bühler-etal-2013/>

As the decay process produces an [[electron neutrino]], some of the suggested explanations for the observed oscillation rate propose new or altered neutrino properties. Ideas related to flavourflavor oscillation met with skepticism.<ref>

|last=Giunti |first=Carlo

|volume=188 |pages=43–45

|issn=0920-5632 |doi=10.1016/j.nuclphysbps.2009.02.009

|arxiv=0812.1887 |bibcode=2009NuPhS.188...43G

|citeseerx=10.1.1.250.3294 |s2cid=10196271

|volume=8 |issue=6 |page=49

|issn=2073-8994 |doi=10.3390/sym8060049

|arxiv=1407.1789 |s2cid=14287612 |bibcode=2016Symm....8...49G

|doi-access=free

}}

== Sources ==

=== Artificial ===

==== Reactor neutrinos ====

[[Nuclear reactor]]sreactors are the major source of human-generated neutrinos. The majority of energy in a nuclear reactor is generated by fission (the four main fissile isotopes in nuclear reactors are {{SimpleNuclide|uranium|235|link=yes}}, {{SimpleNuclide|uranium|238|link=yes}}, {{SimpleNuclide|plutonium|239|link=yes}} and {{SimpleNuclide|plutonium|241|link=yes}}), the resultant neutron-rich daughter nuclides rapidly undergo additional [[beta decay]]sdecays, each converting one neutron to a proton and an electron and releasing an electron antineutrino. Including these subsequent decays, the average nuclear fission releases about {{val|200|u=MeV}} of energy, of which roughly 95.5% remains in the core as heat, and roughly 4.5% (or about {{val|9|u=MeV}})<ref>

|archive-date=2006-04-25
}}

|first1=Adam |last1=Bernstein

|first2=Yifang |last2=Wang |author-link2=Wang Yifang

|first4=Todd |last4=West

==== Accelerator neutrinos ====

Some [[particle accelerator]]s have been used to make neutrino beams. The technique is to collide [[proton]]s with a fixed target, producing charged [[pion]]s or [[kaon]]s. These unstable particles are then magnetically focused into a long tunnel where they decay while in flight. Because of the [[Lorentz transformation|relativistic boost]] of the decaying particle, the neutrinos are produced as a beam rather than isotropically. Efforts to design an accelerator facility where neutrinos are produced through [[muon]] decays are ongoing.<ref name=Bandypdhy-Choubey-Gandhi-Goswami-etal-2009/> Such a setup is generally known as a [[Neutrino Factory|"neutrino factory"]].

==== Collider neutrinos ====

==== Nuclear weapons ====

|last2=Cowan |first2=Clyde L. Jr.

|volume=25 |page=3

=== Geologic ===

=== Atmospheric ===

Atmospheric neutrinos result from the interaction of [[cosmic ray]]srays with atomic nuclei in the [[Earth's atmosphere]], creating showers of particles, many of which are unstable and produce neutrinos when they decay. A collaboration of particle physicists from [[Tata Institute of Fundamental Research]] (India), [[Osaka City University]] (Japan) and [[Durham University]] (UK) recorded the first cosmic ray neutrino interaction in an underground laboratory in [[Kolar Gold Fields]] in India in 1965.<ref name=Krishnswmy-Menon-Narasmhn-etal-1971/>

=== Solar ===

=== Supernovae ===

[[Image:Supernova-1987a.jpg|thumb|[[supernova 1987a|SN 1987A]]]]

Colgate and White's theory of supernova neutrino production was confirmed in 1987, when neutrinos from [[SN 1987A|Supernova&nbsp;1987A]] were detected. The water-based detectors [[Kamiokande II]] and [[Irvine–Michigan–Brookhaven (detector)|IMB]] detected 11 and 8&nbsp;antineutrinos ([[lepton number]]&nbsp;=&nbsp;&minus;1) of thermal origin,<ref name=Mann-1997-SN1987A/> respectively, while the scintillator-based [[Baksan Neutrino Observatory|Baksan]] detector found 5&nbsp;neutrinos ([[lepton number]]&nbsp;=&nbsp;+1) of either thermal or electron-capture origin, in a burst less than 13&nbsp;seconds long. The neutrino signal from the supernova arrived at Earth several hours before the arrival of the first electromagnetic radiation, as expected from the evident fact that the latter emerges along with the shock wave. The exceptionally feeble interaction with normal matter allowed the neutrinos to pass through the churning mass of the exploding star, while the electromagnetic photons were slowed.

Because neutrinos interact so little with matter, it is thought that a supernova's neutrino emissions carry information about the innermost regions of the explosion. Much of the ''visible'' light comes from the decay of radioactive elements produced by the supernova shock wave, and even light from the explosion itself is scattered by dense and turbulent gases, and thus delayed. The neutrino burst is expected to reach Earth before any electromagnetic waves, including visible light, gamma rays, or radio waves. The exact time delay of the electromagnetic waves' arrivals depends on the velocity of the shock wave and on the thickness of the outer layer of the star. For a Type&nbsp;II supernova, astronomers expect the neutrino flood to be released seconds after the stellar core collapse, while the first electromagnetic signal may emerge hours later, after the explosion shock wave has had time to reach the surface of the star. The [[SupernovaSuperNova Early Warning System]] project uses a network of neutrino detectors to monitor the sky for candidate supernova events; the neutrino signal will provide a useful advance warning of a star exploding in the [[Milky Way]].

For an average supernova, approximately {{10^|+57}} (an [[octodecillion]]) neutrinos are released, but the actual number detected at a terrestrial detector <math>N</math> will be far smaller, at the level of

=== Supernova remnants ===

The energy of supernova neutrinos ranges from a few to several tens of MeV. The sites where [[cosmic rays]] are accelerated are expected to produce neutrinos that are at least one million times more energetic, produced from turbulent gaseous environments left over by supernova explosions: [[Supernova remnant]]s. The origin of the cosmic rays was attributed to supernovas by [[Walter Baade|Baade]] and [[Fritz Zwicky|Zwicky]]; this hypothesis was refined by [[Vitaly L. Ginzburg|Ginzburg]] and [[Sergei I. Syrovatsky|Syrovatsky]] who attributed the origin to supernova remnants, and supported their claim by the crucial remark, that the cosmic ray losses of the Milky Way is compensated, if the efficiency of acceleration in supernova remnants is about 10&nbsp;percent. [[Vitaly L. Ginzburg|Ginzburg]] and Syrovatskii's hypothesis is supported by the specific mechanism of "shock wave acceleration" happening in supernova remnants, which is consistent with the original theoretical picture drawn by [[Enrico Fermi]], and is receiving support from observational data. The very high-energy neutrinos are still to be seen, but this branch of neutrino astronomy is just in its infancy. The main existing or forthcoming experiments that aim at observing very-high-energy neutrinos from our galaxy are [[Baikal Deep Underwater Neutrino Telescope|Baikal]], [[Antarctic Muon And Neutrino Detector Array|AMANDA]], [[IceCube]], [[ANTARES (telescope)|ANTARES]], [[Neutrino Mediterranean ObservatoryKM3NeT|NEMO]] and [[Nestor Project|Nestor]]. Related information is provided by [[ultra-high-energy gamma ray|very-high-energy gamma ray]] observatories, such as [[VERITAS]], [[High Energy Stereoscopic System|HESS]] and [[MAGIC (telescope)|MAGIC]]. Indeed, the collisions of cosmic rays are supposed to produce charged pions, whose decay give the neutrinos, neutral pions, and gamma rays the environment of a supernova remnant, which is transparent to both types of radiation.

Still-higher-energy neutrinos, resulting from the interactions of extragalactic cosmic rays, could be observed with the [[Pierre Auger Observatory]] or with the dedicated experiment named [[ANtarcticAntarctic ImpulseImpulsive Transient Antenna|ANITA]].

=== Big Bang ===

It is thought that, just like the [[cosmic microwave background radiation]] leftover from the [[Big Bang]], there is a background of low-energy neutrinos in our Universe. In the 1980s it was proposed that these may be the explanation for the [[dark matter]] thought to exist in the universe. Neutrinos have one important advantage over most other dark matter candidates: They are known to exist. This idea also has serious problems.

From particle experiments, it is known that neutrinos are very light. This means that they easily move at speeds close to the [[speed of light]]. For this reason, dark matter made from neutrinos is termed "[[hot dark matter]]". The problem is that being fast moving, the neutrinos would tend to have spread out evenly in the [[universe]] before cosmological expansion made them cold enough to congregate in clumps. This would cause the part of [[dark matter]] made of neutrinos to be smeared out and unable to cause the large [[galaxy|galactic]] structures that we see.

From cosmological arguments, relic background neutrinos are estimated to have density of 56&nbsp;of&nbsp;each type per cubic centimeter and temperature {{val|1.9|u=K}} ({{val|1.7|e=-4|u=eV}}) if they are massless, much colder if their mass exceeds {{val|0.001|u=eV/c2}}. Although their density is quite high, they have not yet been observed in the laboratory, as their energy is below thresholds of most detection methods, and due to extremely low neutrino interaction cross-sections at sub-eV energies. In contrast, [[boron-8]] solar neutrinos – whichneutrinos—which are emitted with a higher energy – haveenergy—have been detected definitively despite having a space density that is lower than that of relic neutrinos by some six [[orders of magnitude]].

== Detection ==

Neutrinos cannot be detected directly because they do not carry electric charge, which means they do not ionize the materials they pass through. Other ways neutrinos might affect their environment, such as the [[MSW effect]], do not produce traceable radiation. A unique reaction to identify antineutrinos, sometimes referred to as [[inverse beta decay]], as applied by Reines and Cowan (see below), requires a very large detector to detect a significant number of neutrinos. All detection methods require the neutrinos to carry a minimum threshold energy. So far, there is no detection method for low-energy neutrinos, in the sense that potential neutrino interactions (for example by the MSW effect) cannot be uniquely distinguished from other causes. Neutrino detectors are often built underground to isolate the detector from [[cosmic ray]]srays and other background radiation.

Antineutrinos were first detected in the 1950s near a nuclear reactor. [[Frederick Reines|Reines]] and [[Clyde Cowan|Cowan]] used two targets containing a solution of [[cadmium chloride]] in water. Two scintillation detectors were placed next to the cadmium targets. Antineutrinos with an energy above the threshold of {{val|1.8|u=MeV}} caused charged current interactions with the protons in the water, producing positrons and neutrons. This is very much like {{SubatomicParticle|Beta+}} decay, where energy is used to convert a proton into a neutron, a [[positron]] ({{SubatomicParticle|Positron}}) and an [[electron neutrino]] ({{SubatomicParticle|Electron Neutrino}}) is emitted:

:{{block indent|Energy (>&nbsp;{{val|1.8|u=MeV}}) {{math| + {{SubatomicParticle|Proton}} + {{SubatomicParticle|Electron antineutrino}} → {{SubatomicParticle|Neutron}} + {{SubatomicParticle|Positron}} }}}}

Since then, various detection methods have been used. [[Super Kamiokande]] is a large volume of water surrounded by [[photomultiplier tube]]s that watch for the [[Cherenkov radiation]] emitted when an incoming neutrino creates an [[electron]] or [[muon]] in the water. The [[Sudbury Neutrino Observatory]] is similar, but used [[heavy water]] as the detecting medium, which uses the same effects, but also allows the additional reaction any-flavor neutrino photo-dissociation of deuterium, resulting in a free neutron which is then detected from gamma radiation after chlorine-capture. Other detectors have consisted of large volumes of [[chlorine]] or [[gallium]] which are periodically checked for excesses of [[argon]] or [[germanium]], respectively, which are created by electron-neutrinos interacting with the original substance. [[MINOS]] used a solid plastic [[scintillator]] coupled to photomultiplier tubes, while [[Borexino]] uses a liquid [[pseudocumene]] scintillator also watched by photomultiplier tubes and the [[NOνA]] detector uses liquid scintillator watched by [[avalanche photodiode]]s. The [[IceCube Neutrino Observatory]] uses {{val|1|u=km3}} of the [[Antarctic ice sheet]] near the [[south pole]] with photomultiplier tubes distributed throughout the volume.

== Scientific interest ==

Using neutrinos as a probe was first proposed in the mid-20th&nbsp;century as a way to detect conditions at the core of the Sun. The solar core cannot be imaged directly because electromagnetic radiation (such as light) is diffused by the great amount and density of matter surrounding the core. On the other hand, neutrinos pass through the Sun with few interactions. Whereas photons emitted from the solar core may require {{val|40,000}}&nbsp;years to diffuse to the outer layers of the Sun, neutrinos generated in stellar fusion reactions at the core cross this distance practically unimpeded at nearly the speed of light.<ref name=Bahcall-1989-ν-astroph/><ref name=Davis-2003-NobLects/>

Neutrinos are also useful for probing [[Neutrino astronomy|astrophysical]] sources beyond the Solar System because they are the only known particles that are not significantly [[attenuation|attenuated]] by their travel through the interstellar medium. Optical photons can be obscured or diffused by dust, gas, and background radiation. High-energy [[cosmic rays]], in the form of swift protons and atomic nuclei, are unable to travel more than about 100&nbsp;[[megaparsec]]s due to the [[Greisen–Zatsepin–Kuzmin limit]] (GZK cutoff). Neutrinos, in contrast, can travel even greater distances barely attenuated.

The galactic core of the [[Milky Way]] is fully obscured by dense gas and numerous bright objects. Neutrinos produced in the galactic core might be measurable by Earth-based [[neutrino telescope]]s.<ref name=Close-2012-ν/>

Another important use of the neutrino is in the observation of [[supernova]]e, the explosions that end the lives of highly massive stars. The core collapse phase of a supernova is an extremely dense and energetic event. It is so dense that no known particles are able to escape the advancing core front except for neutrinos. Consequently, supernovae are known to release approximately 99% of their [[radiant energy]] in a short (10&nbsp;-second) burst of neutrinos.<ref name=Minkel-2009-07-17-ν-gunsmoke/> These neutrinos are a very useful probe for core collapse studies.

The rest mass of the neutrino is an important test of cosmological and astrophysical theories (see ''[[Dark matter]]''). The neutrino's significance in probing cosmological phenomena is as great as any other method, and is thus a major focus of study in astrophysical communities.<ref name=Gelmini-Kusenko-Weiler-2010/>

The study of neutrinos is important in [[particle physics]] because neutrinos typically have the lowest rest mass among massive particles (i.e. the lowest non-zero rest mass, i.e. excluding the zero rest mass of photons and gluons), and hence are examples of the lowest-energy massive particles theorized in extensions of the [[Standard Model]] of particle physics.

In July&nbsp;2018, the [[IceCube Neutrino Observatory]] announced that they have traced an extremely-high-energy neutrino that hit their Antarctica-based research station in September&nbsp;2017 back to its point of origin in the blazar [[TXS 0506 +056]] located 3.7&nbsp;billion [[light-year]]s away in the direction of the constellation [[Orion (constellation)|Orion]]. This is the first time that a [[neutrino detector]] has been used to locate an object in space and that a source of [[cosmic rays]] has been identified.<ref name=Overbye-2018-07-12-Antc-ν/><ref name=Sample-2018-07-12-ν-Antc/><ref name=Halton-2018-07-12-ν-src/>

In November&nbsp;2022, the [[IceCube Neutrino Observatory]] found evidence of high-energy neutrino emission from NGC 1068, also known as [[Messier 77]], an active galaxy in the constellation Cetus and one of the most familiar and well-studied galaxies to date.<ref>{{cite press release |url=https://icecube.wisc.edu/news/press-releases/2022/11/icecube-neutrinos-give-us-first-glimpse-into-the-inner-depths-of-an-active-galaxy/ |title=IceCube neutrinos give us first glimpse into the inner depths of an active galaxy |work=[[IceCube Neutrino Observatory]] |publisher=[[University of Wisconsin–Madison]] |date=3 November 2022 |access-date=22 November 2022}}</ref>

In June 2023, astronomers reported using a new technique to detect, for the first time, the release of neutrinos from the [[galactic plane]] of the [[Milky Way]] [[galaxy]].<ref name="NYT-20230629">{{cite news |last=Chang |first=Kenneth |title=Neutrinos Build a Ghostly Map of the Milky Way - Astronomers for the first time detected neutrinos that originated within our local galaxy using a new technique. |url=https://www.nytimes.com/2023/06/29/science/neutrinos-milky-way-map.html |work=[[The New York Times]] |date=29 June 2023 |url-status=live |archive-url=https://archive.today/20230629182106/https://www.nytimes.com/2023/06/29/science/neutrinos-milky-way-map.html |archive-date=29 June 2023 |access-date=30 June 2023 }}</ref><ref name="SCI-20230629">{{cite journal |author=IceCube Collaboration |title=Observation of high-energy neutrinos from the Galactic plane |url=https://www.science.org/doi/10.1126/science.adc9818 |date=29 June 2023 |journal=[[Science (journal)|Science]] |volume=380 |issue=6652 |pages=1338–1343 |doi=10.1126/science.adc9818 |pmid=37384687 |arxiv=2307.04427 |s2cid=259287623 |url-status=live |archive-url=https://archive.today/20230630042539/https://www.science.org/doi/10.1126/science.adc9818 |archive-date=30 June 2023 |access-date=30 June 2023 }}</ref>

== See also ==

* {{annotated linkanl|List of neutrino experiments}}

* {{annotated linkanl|Multi-messenger astronomy}}

* {{annotated linkanl|Neutrino oscillation}}

* {{annotated linkanl|Neutrino astronomy}}

* [[Pontecorvo–Maki–Nakagawa–Sakata matrix{{anl|PMNS matrix]] — the Pontecorvo–Maki–Nakagawa–Sakata matrix}}

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|last4=Goswami |first4=Srubabati |author-link4=Srubabati Goswami

|last5=Roberts |first5=B. Lee |last6=Bouchez |first6=Jacques

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|volume=60 |pages=439–462

|last2=Vogel |first2=Petr

|first2=Richard H. |last2=White

|first1=Ivan |last1=Esteban |first2=Concha |last2=Gonzalez Garcia

|first3=Michele |last3=Maltoni |first4=Thomas |last4=Schwetz

|first5=Zhou |last5=Albert

|access-date=2020-12-29
}}

|last1=Fukuda |first1=Yoshiyuki |last2=Hayakawa |first2=Takashi

|last3=Ichihara |first3=E. |last4=Inoue |first4=Kunio

|last5=Ishihara |first5=Ken |last6=Ishino |first6=Hirokazu

|last7=Itow |first7=Y. |last8=Kajita |first8=T.

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|last17=Nakayama |first17=S. |last18=Okada |first18=A.

|last19=Oketa |first19=M. |last20=Okumura |first20=K.

|last21=Ota |first21=M. |last22=Sakurai |first22=N.

|last23=Shiozawa |first23=M. |last24=Suzuki |first24=Y.

|last25=Takeuchi |first25=Y. |last26=Totsuka |first26=Y.

|last27=Yamada |first27=S. |last28=Earl |first28=M.

|last29=Habig |first29=A. |last30=Hong |first30=J.T.

|volume=81 |issue=6 |pages=1158–1162

|arxiv=hep-ex/9805021 |bibcode=1998PhRvL..81.1158F

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|last1=Gando |first1=Azusa |last2=Gando |first2=Yoshihito

|last3=Hanakago |first3=H. |last4=Ikeda |first4=Haruo

|last5=Inoue |first5=Kunio |last6=Ishidoshiro |first6=Koji

|last7=Ishikawa |first7=H. |last8=Koga |first8=Masayuki <!--

|date=2013-08-02 |title=Reactor on-off antineutrino measurement with KamLAND

|last2=Kusenko |first2=Alexander |author2-link=Alexander Kusenko

|last3=Weiler |first3=Thomas J.

|first1=Carlo |last1=Giunti

|isbn=978-0-19-850871-7
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|first=Mary |last=Halton

|last1=Kelić |first1=Aleksandra |last2=Zinner |first2=Nikolaj T.

|last3=Kolbe |first3=Edwin |last4=Langanke |first4=Karlheinz

|last1=Kienle |first1=Paul |last2=Bosch |first2=Fritz

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|last5=Litvinov |first5=Yuri A. |last6=Sanjari |first6=M. Shahab

|last7=Shubina |first7=D.B. |last8=Winckler |first8=N.

|last9=Atanasov |first9=D. |last10=Geissel |first10=H.

|last11=Ivanova |first11=V. |last12=Yan |first12=X.L.

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|last21=Kurcewicz |first21=J. |last22=Kuzminchuk |first22=N.

|last23=Lestinsky |first23=M. |last24=Litvinov |first24=Sergey A.

|last25=Ma |first25=X.W. |last26=Maier |first26=L.

|last27=Mazzocco |first27=M. |last28=Mukha |first28=I.

|last29=Nociforo |first29=C. |last30=Nolden |first30=F.

|last33=Steck |first33=M. |last34=Stöhlker |first34=Th.

|last35=Sun |first35=B.H. |last36=Suzaki |first36=F.

|last37=Suzuki |first37=T. |last38=Torilov |first38=S.Yu.

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|last41=Wang |first41=M. |last42=Weick |first42=H.

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|last2=Menon |first2=Mambillikalathil Govind Kumar |author-link2=M. G. K. Menon

|last3=Narasimhan |first3=V.S. <!-- maybe Mudumbai Seshachalu? -->

|last4=Hinotani |first4=Kensaku |last5=Ito |first5=Nobuo

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|last4=Barenboim |first4=Gabriela |last5=Chen |first5=Mu-Chun

|last6=de Gouvêa |first6=André |last7=de Holanda |first7=Pedro Cunha

|last8=Dutta |first8=Bhaskar |last9=Grossman |first9=Yuval

|last10=Joshipura |first10=Anjan S. |last11=Kayser |first11=Boris J.

|last12=Kersten |first12=Joern |last13=Keum |first13=Yong-Yeon

|last14=King |first14=Stephen F. |last15=Langacker |first15=Paul

|last16=Lindner |first16=Manfred |last17=Loinaz |first17=Will A.

|last18=Masina |first18=Isabella |last19=Mocioiu |first19=Irina

|last20=Mohanty |first20=Subhendra |last21=Murayama |first21=Hitoshi

|last22=Pascoli |first22=Silvia |last23=Petcov |first23=Serguey Todorov

|last24=Pilaftsis |first24=A. |last25=Ramond |first25=P.

|last26=Ratz |first26=M. |last27=Rodejohann |first27=W.

|last28=Shrock |first28=R. |last29=Takeuchi |first29=T.

|arxiv=hep-ph/0510213 |bibcode=2007RPPh...70.1757M

|s2cid=119092531 |doi=10.1088/0034-4885/70/11/R02

|last=Sample |first=Ian

|last1=Stancil |first1=Daniel D. |last2=Adamson |first2=Philip

|last3=Alania |first3=Marcos |last4=Aliaga Soplin |first4=Leo

|last5=Andrews |first5=Michael P. |last6=Araujo del Castillo |first6=Carmen

|last7=Bagby |first7=L. |last8=Bazo Alba |first8=J.L.

|last9=Bodek |first9=A. |last10=Boehnlein |first10=D.

|last11=Bradford |first11=R. |last12=Brooks |first12=W.K.

|last13=Budd |first13=H. |last14=Butkevich |first14=A.

|last15=Caicedo |first15=D.A.M. |last16=Capista |first16=D.P.

|last17=Castromonte |first17=C.M. |last18=Chamorro |first18=A.

|last19=Charlton |first19=E. |last20=Christy |first20=M.E.

|last21=Chvojka |first21=J. |last22=Conrow |first22=P.D.

|last23=Danko |first23=I. |last24=Day |first24=M.

|last25=Devan |first25=J. |last26=Downey |first26=J.M.

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== External links ==

|first2=Carlo |last2=Giunti

|first3=Marco |last3=Laveder

|first2=Irina V. |last2=Krivosheina

|first3=Alexander |last3=Dietz

|first4=Oleg |last4=Chkvorets

|last2=Copeland |first2=Ed |author-link2=Edmund Copeland

|last3=Bowley |first3=Roger

|website=[[YouTube]] |medium=lecture video