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85-567: The Deep Underground Neutrino Experiment ( DUNE ) is a neutrino experiment under construction, with a near detector at Fermilab and a far detector at the Sanford Underground Research Facility that will observe neutrinos produced at Fermilab . An intense beam of trillions of neutrinos from the production facility at Fermilab (in Illinois ) will be sent over a distance of 1,300 kilometers (810 mi) with

170-425: A 5σ understanding of the mass ordering were more hopeful in a head-to-head competition with Hyper-K, with DUNE beating Hyper-K by two years if the 2022 schedule does not slip. This is because Hyper-K has a shorter baseline than DUNE, and capability of determining the mass-ordering depends on distance the neutrinos travel. However, both DUNE and Hyper-K are predicted to be scooped on the mass ordering by combination of

255-706: A US-only project called the Long Baseline Neutrino Experiment ( LBNE ); in around 2012–2014 a descope was considered with a near-surface detector to reduce cost. However, the Particle Physics Project Prioritization Panel (P5) concluded in its 2014 report that the research activity being pursued by LBNE "should be reformulated under the auspices of a new international collaboration, as an internationally coordinated and internationally funded program, with Fermilab as host". The LBNE collaboration

340-400: 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 packets develop relative phase shifts that change how they combine to produce

425-594: 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. Neutrinos are created by various radioactive decays ;

510-628: 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 or 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 would be allowed, while they would not if neutrinos are Dirac particles. Several experiments have been and are being conducted to search for this process, e.g. GERDA , EXO , SNO+ , and CUORE . The cosmic neutrino background

595-504: A gamma ray. The coincidence of both events—positron annihilation and neutron capture—gives a unique signature of an antineutrino interaction. In February 1965, the first neutrino found in nature was identified by a group including Frederick Reines and Friedel Sellschop . The experiment was performed in a specially prepared chamber at a depth of 3 km in the East Rand ("ERPM") gold mine near Boksburg , South Africa. A plaque in

680-597: A history of lower-than-requested congressional appropriations for the project, at the same November 2021 meeting, DOE presented a "conservative profile [for funding] that the Office of Science can support." In March, 2022, as part of the CD-1RR process, DOE announced that the project would be completed in two phases. The plan for phasing was announced during the Snowmass Process , an exercise periodically organized by

765-605: A laboratory, but is predicted to happen within stars and supernovae. The process affects the abundance of isotopes seen in the universe . Neutrino-induced disintegration of deuterium nuclei has been observed in the Sudbury Neutrino Observatory, which uses a heavy water detector. There are three known types ( flavors ) of neutrinos: electron neutrino ν e , muon neutrino ν μ , and tau neutrino ν τ , named after their partner leptons in

850-419: A muon or tau neutrino. The three mass values are not yet known as of 2024, but laboratory experiments and cosmological observations have determined the differences of their squares, an upper limit on their sum (<  2.14 × 10  kg ), and an upper limit on the mass of the electron neutrino. Neutrinos are fermions with spin of ⁠ 1  / 2 ⁠ . For each neutrino, there also exists

935-473: A new major field of research that still continues. Eventual confirmation of the phenomenon of neutrino oscillation led to two Nobel prizes, one to 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 A.B. McDonald of Sudbury Neutrino Observatory for their joint experiment, which confirmed

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1020-566: A process analogous to light traveling through a transparent material . This process is not directly observable because it does not produce ionizing radiation , but gives rise to the Mikheyev–Smirnov–Wolfenstein effect . Only a small fraction of the neutrino's energy is transferred to the material. Onia 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

1105-418: A proton, electron, and the smaller neutral particle (now called an electron antineutrino ): Fermi's paper, written in 1934, unified Pauli's neutrino with Paul Dirac 's positron and Werner Heisenberg 's neutron–proton model and gave a solid theoretical basis for future experimental work. By 1934, there was experimental evidence against Bohr's idea that energy conservation is invalid for beta decay: At

1190-419: A total volume of 70-kilotons of liquid argon located deep underground, 1.5 kilometers (4,850 ft) under the surface. The current design divides the liquid argon between four LArTPC modules with a "fiducial volume" (the volume usable for physics analysis, which is smaller than the total volume to avoid interactions near detector edges) of 10 kilotons each. About 800,000 tons of rock will be excavated to create

1275-605: 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. There are other possibilities in which neutrinos could oscillate even if they were massless: If Lorentz symmetry were not an exact symmetry, neutrinos could experience Lorentz-violating oscillations . Neutrinos traveling through matter, in general, undergo

1360-497: A £65M investment in DUNE and LBNF. By 2022, the international partners providing in-kind contributions also included CERN , Brazil, Switzerland and Poland and the total foreign contribution to the $ 3B project was $ 570M, or about 20%. In August 2024, scientists detected the first neutrinos using a DUNE prototype particle detector at the U.S. Department of Energy’s Fermi National Accelerator Laboratory . The original scope and cost for

1445-415: 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 ). 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

1530-529: Is a 260 kton total volume detector under construction 295 km from the Japan Proton Accelerator Research Complex ( J-PARC ) neutrino source. Construction is estimated to be completed by 2027. The Japanese government has had strict cost controls and has not allowed the costs to Japan to extend beyond the original 2016 estimate of approximately $ 600M. The project has received about $ 150M in international contributions. Thus,

1615-472: Is also a probe of whether neutrinos are Majorana particles , since there should be a different number of cosmic neutrinos detected in either the Dirac or Majorana case. Neutrinos can interact with a nucleus, changing it to another nucleus. This process is used in radiochemical neutrino detectors . In this case, the energy levels and spin states within the target nucleus have to be taken into account to estimate

1700-493: 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. A neutrino created in a specific flavor eigenstate is in an associated specific quantum superposition of all three mass eigenstates. The three masses differ so little that they cannot possibly be distinguished experimentally within any practical flight path. The proportion of each mass state in

1785-463: Is important to understand because many neutrinos emitted by fusion in the Sun pass through the dense matter in the solar core (where essentially all solar fusion takes place) on their way to detectors on Earth. Starting in 1998, experiments began to show that solar and atmospheric neutrinos change flavors (see Super-Kamiokande and Sudbury Neutrino Observatory ). This resolved the solar neutrino problem:

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1870-519: Is integral to the "improved tritium management [that is] a major focus on the design of this new, higher beam power facility." Tritium produced by beamlines can enter the surface ground water, however rates at Fermilab are maintained at a level well below that allowed by regulations. In order to provide 1.2 MW of protons to LBNF, the second phase of the Proton Improvement Project ("PIP II"), which will increase proton delivery from

1955-533: Is no experimental evidence for a non-zero magnetic moment in neutrinos. Weak interactions create neutrinos in one of three leptonic flavors : electron neutrinos ( ν e ), muon neutrinos ( ν μ ), or tau neutrinos ( ν τ ), associated with the corresponding charged leptons, the electron ( e ), muon ( μ ), and tau ( τ ), respectively. Although neutrinos were long believed to be massless, it

2040-456: Is now known that there are three discrete neutrino masses; each neutrino flavor state is a linear combination of the three discrete mass eigenstates. Although only differences of squares of the three mass values are known as of 2016, experiments have shown that these masses are tiny compared to any other particle. From cosmological measurements, it has been calculated that the sum of the three neutrino masses must be less than one-millionth that of

2125-482: Is the longest continuously running LArTPC detector, having taken data from 2015 to 2021—considerably shorter than the time-period of 20 years expected for DUNE. The DUNE near detector will be located on the Fermilab site, downstream of LBNF, about 600 meters from where the neutrinos are produced. The DUNE near detector comprises several subdetectors that will sit side by side. One of these (SAND) will be installed along

2210-475: The 1995 Nobel Prize . 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 neutrons and positrons: The positron quickly finds an electron, and they annihilate each other. The two resulting gamma rays (γ) are detectable. The neutron can be detected by its capture on an appropriate nucleus, releasing

2295-537: The Hyper-Kamiokande experiment in Japan, scheduled to begin data-taking in 2027. The DUNE project, overseen by Fermilab , has suffered delays to its schedule and growth of cost from less than $ 2B to more than $ 3B, leading to articles in the journals Science and Scientific American that described the project as "troubled." In 2022, the DUNE experiment had a neutrino-beam start-date in the early-2030's, and

2380-664: The JUNO experiment in China and a set of atmospheric neutrino experiments that exist or are now under construction. Fermilab Director Merminga was confronted about the potential for DUNE to be scooped by the competition in a presentation to the House Science Committee in June 2022. In response, Merminga claimed that the projects are complementary, with DUNE providing more precise reconstructions of neutrino interactions due to

2465-455: The Solvay conference of that year, measurements of the energy spectra of beta particles (electrons) were reported, showing that there is a strict limit on the energy of electrons from each type of beta decay. Such a limit is not expected if the conservation of energy is invalid, in which case any amount of energy would be statistically available in at least a few decays. The natural explanation of

2550-520: The Standard Model (see table at right). The current best measurement of the number of neutrino types comes from observing the decay of the Z boson . This particle can decay into any light neutrino and its antineutrino, and the more available types of light neutrinos, the shorter the lifetime of the Z ;boson. Measurements of the Z lifetime have shown that three light neutrino flavors couple to

2635-523: The cosmic neutrino background (CNB). R. Davis and 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 . SN 1987A represents

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2720-489: The electromagnetic interaction or the strong interaction . Thus, neutrinos typically pass through normal matter unimpeded and undetected. Weak interactions create neutrinos in one of three leptonic flavors : Each flavor is associated with the correspondingly named charged lepton . 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 ), but

2805-529: The muon neutrino (already hypothesised with the name neutretto ), which earned them the 1988 Nobel Prize in Physics . When the third type of lepton, the 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

2890-405: 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. James Chadwick discovered a much more massive neutral nuclear particle in 1932 and named it a neutron also, leaving two kinds of particles with the same name. The word "neutrino" entered

2975-454: The 2015 Nobel Prize for Physics for their landmark finding, theoretical and experimental, that neutrinos can change flavors. As well as specific sources, a general background level of neutrinos is expected to pervade the universe, theorized to occur due to two main sources. Around 1 second after the Big Bang , neutrinos decoupled, giving rise to a background level of neutrinos known as

3060-775: The Division of Particles and Fields (DPF) of the American Physical Society to plan the future of particle physics. Nominally, Phase I would consist of the first two far detector modules, a subset of the near detector system, and the 1.2 MW beamline, to be completed by 2032 for the estimated $ 3.1B cost. The CD-1RR process was completed on February 16, 2023, with an estimated cost for the project of $ 3.3B and an upper allowed cost range of $ 3.7B. To meet this cost, detector module 2 will be only 40% filled with liquid argon at project completion, and therefore not immediately usable for physics. The $ 3.3B cost does not include

3145-545: The Earth, reaching about 30 kilometers (19 mi) underground near the mid-point, to arrive at the underground laboratory in Lead, South Dakota. To point the neutrinos toward the underground laboratory, the beam must be directed into the earth at a steep angle. LBNF construction will include a 58-foot-high hill made of compacted soil, connecting to a 680-foot-long tunnel that will contain a 635-foot-long particle decay pipe. The hill

3230-546: The Fermilab accelerator chain by 60%, must be completed. The cost of this Fermilab upgrade as of 2022 is $ 1.28B. Thus, the PIP II and DUNE Phase I combined costs exceed $ 4B. The PIP II project received approval to begin construction in April 2022 and is expected to be completed by 2028. The DUNE far detector design is based on state-of-the-art Liquid Argon Time Projection Chamber (LArTPC) technology. The far detector will consist of

3315-595: The LBNE project was established in step-1 of the Department of Energy "Critical Decision" process. Approval of CD-1 occurred in December 2012 The approved design significantly scaled back the physicist's request, which cost $ 1.7B. The CD-1 approval was for a budget of $ 850M, the proposed near detector was not included and the far detectors were recommended to be located on the surface rather than underground. Following

3400-515: The MiniBooNE low-energy excess, one under a single photon hypothesis and under an electron hypothesis. No evidence for either of these explanations was found within MicroBooNE's sensitivity, which is set by the statistics and systematic uncertainty. The Fermilab press release accompanying the results claimed that the electron hypothesis test dealt "a blow to a theoretical particle known as

3485-603: The Open Cut due to DUNE construction led to complaints from businesses, homeowners, and users of a nearby park. Complaints continued through spring 2022 without adequate response from Fermilab management, resulting in the South Dakota Science and Technology Authority shutting down excavation on March 31, 2022. An investigation ensued in which the Fermilab management team admitted to failures in protocols, and instigated new measures to prevent black dust from leaving

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3570-460: The Open Cut. With these assurances in place, Fermilab was allowed to resume rock dumping on April 8, 2022 and the project was completed two years later. Neutrino A neutrino ( / nj uː ˈ t r iː n oʊ / new- TREE -noh ; denoted by the Greek letter ν ) is an elementary particle that interacts via the weak interaction and gravity . The neutrino is so named because it

3655-547: The P5 recommendation for a more robust project scope that included underground detectors, the project received a first CD-1 reaffirmation ("CD-1R") under the name LBNF/DUNE in November 2015. The scope of LBNF/DUNE was published in the 2016 Conceptual Design Report called for the first two far detector modules to be completed in 2024, the beam to be operational in 2026, and the four modules to be operational in 2027. The DOE estimated

3740-537: The Z. The correspondence between the six quarks in the Standard Model and the six leptons, among them the three neutrinos, suggests to physicists' intuition that there should be exactly three types of neutrino. There are several active research areas involving the neutrino with aspirations of finding: International scientific collaborations install large neutrino detectors near nuclear reactors or in neutrino beams from particle accelerators to better constrain

3825-401: The approximately $ 1B price of the PIP II upgrade that is required for DUNE, nor $ 660M promised as of February, 2023, from international partners for DUNE. Including these funds, the total cost for Phase I of LBNF/DUNE at the end of the CD-1RR review process was close to $ 5B. Phase II would complete the full scope by adding the additional two far modules, completing the suite of subdetectors at

3910-529: 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 collaboration at Fermilab ; its existence had already been inferred by both theoretical consistency and experimental data from the Large Electron–Positron Collider . In the 1960s, the now-famous Homestake experiment made the first measurement of

3995-471: The beta decay spectrum as first measured in 1934 was that only a limited (and conserved) amount of energy was available, and a new particle was sometimes taking a varying fraction of this limited energy, leaving the rest for the beta particle. Pauli made use of the occasion to publicly emphasize that the still-undetected "neutrino" must be an actual particle. The first evidence of the reality of neutrinos came in 1938 via simultaneous cloud-chamber measurements of

4080-534: The caverns for the far detectors. Since LArTPCs are relatively new technology, extensive R&D and prototyping have been required. Prototype detectors are being constructed and tested at CERN . The first of the two prototypes, the single-phase ProtoDUNE (CERN experiment NP04), recorded its first particle tracks in September 2018. CERN's participation in DUNE marked a new direction in CERN's neutrino's research and

4165-409: 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; what experiments observe as

4250-466: The context of preventing the proliferation of nuclear weapons . Because antineutrinos and neutrinos are neutral particles, it is possible that they are the same particle. Rather than conventional Dirac fermions , neutral particles can be another type of spin  ⁠ 1  / 2 ⁠ particle called Majorana particles , named after the Italian physicist Ettore Majorana who first proposed

4335-529: The cost of Hyper-K is approximately equal to the CD-1 approved cost for LBNE (the DUNE predecessor) in the early 2010's. In comparison the DUNE Phase I detector is much smaller---only 17 kt---and the distance from the Fermilab neutrino source to the detector is longer---1300 km. This leads to a much lower expected rate of interactions in DUNE than Hyper-K. Also, the timescale of Hyper-K remains on-track, and so

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4420-553: The detector can be expected to start taking data 4 to 5 years earlier than the present projections for DUNE. The premiere result from DUNE on CP violation is predicted to lag the result from Hyper-K by 5 years. The final report of the Snowmass 2021 Topical Group Report on Three-Flavor Neutrino Oscillations released on June 15, 2022 estimated that a 5σ (hence discovery level) result on CP violation would be released from Hyper-K in 2034 and from DUNE in 2039. Estimations on reaching

4505-417: The electron and the recoil of the nucleus. In 1942, Wang Ganchang first proposed the use of beta capture to experimentally detect neutrinos. In the 20 July 1956 issue of Science , Clyde Cowan , Frederick Reines , Francis B. "Kiko" Harrison, Herald W. Kruse, and Austin D. McGuire published confirmation that they had detected the neutrino, a result that was rewarded almost forty years later with

4590-572: The electron neutrino, with other approaches to this problem in the planning stages. MicroBooNE MicroBooNE's two main physics goals are to investigate the MiniBooNE low-energy excess and neutrino - argon cross sections . As part of the Short Baseline Neutrino program (SBN), it will be one of a series of neutrino detectors along with the new Short-Baseline Near Detector (SBND) and moved ICARUS detector. MicroBooNE

4675-405: The electron neutrinos produced in the Sun had partly changed into other flavors which the experiments could not detect. Although individual experiments, such as the set of solar neutrino experiments, are consistent with non-oscillatory mechanisms of neutrino flavor conversion, taken altogether, neutrino experiments imply the existence of neutrino oscillations. Especially relevant in this context are

4760-451: The electron. More formally, neutrino flavor eigenstates (creation and annihilation combinations) are not the same as the neutrino mass eigenstates (simply labeled "1", "2", and "3"). As of 2024, 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 2 being lighter than mass 3

4845-600: The existence of all three neutrino flavors and found no deficit. A practical method for investigating neutrino oscillations was first suggested by Bruno Pontecorvo in 1957 using an analogy with kaon oscillations; over the subsequent 10 years, he developed the mathematical formalism and the modern formulation of vacuum oscillations. In 1985 Stanislav Mikheyev and Alexei Smirnov (expanding on 1978 work by Lincoln Wolfenstein ) noted that flavor oscillations can be modified when neutrinos propagate through matter. This so-called Mikheyev–Smirnov–Wolfenstein effect (MSW effect)

4930-481: The experiments are referred to as part of the Neutrino Platform in the laboratory's research programme. The MicroBooNE experiment and ICARUS experiment detectors are a pair of 100-ton-scale LArTPCs in the Fermilab program that also act as R&D platforms for DUNE detector development. These experiments have provided important input, but are more than 20 times smaller than the DUNE modules. MicroBooNE

5015-467: The far detector modules. Excavation of the DUNE far detector cavities began on July 21, 2017. Seven years later, on August 15, 2024, the completion of the caverns was announced. Delays in completion arose from both the complexity of the project underground and from issues with dust release at the surface. Rock removed from underground was deposited in the Open Cut in the center of the city of Lead, South Dakota . In June 2021, plumes of dust rising from

5100-486: 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

5185-399: The following list is not exhaustive, but includes some of those processes: 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 × 10 ) solar neutrinos , per second per square centimeter. Neutrinos can be used for tomography of the interior of the Earth. The neutrino

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5270-489: The goal of understanding the role of neutrinos in the universe. More than 1,000 collaborators work on the project. The experiment is designed for a 20-year period of data collection. The primary science objectives of DUNE are In 2014 the Particle Physics Project Prioritization Panel (P5) ranked this as "the highest priority project in its timeframe" (recommendation 13). The importance of these goals has led to proposals for competing projects in other countries, particularly

5355-593: 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, do not need to be considered for the detection experiment. Within a cubic meter 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. Very much like neutrons do in nuclear reactors , neutrinos can induce fission reactions within heavy nuclei . So far, this reaction has not been measured in

5440-513: The initial state, then the final state has only matched lepton and anti-lepton pairs: electron neutrinos appear in the final state together with only positrons (anti-electrons) or electron antineutrinos, and electron antineutrinos with electrons or electron neutrinos. 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 (i.e., only one of

5525-490: The liquid argon technology than can be achieved in the water-based Hyper-K water detector. However, Merminga did not explain why more precise reconstruction is required given that the water detectors can reach the same physics goals. The Sanford Underground Research Facility makes use of, and is extending, the facilities of the Homestake Mine (South Dakota) , which ceased operations at the end of 2001, to accommodate

5610-505: The main building commemorates the discovery. The experiments also implemented a primitive neutrino astronomy and looked at issues of neutrino physics and weak interactions. The antineutrino discovered by Clyde Cowan and Frederick Reines was the antiparticle of the electron neutrino. In 1962, Leon M. Lederman , Melvin Schwartz , and Jack Steinberger showed that more than one type of neutrino exists by first detecting interactions of

5695-419: The near site and upgrading the beam power to 2.4 MW. Phase II represents cost beyond the $ 3.1B estimate for Phase I and has been estimated to be at least an additional $ 900M. Physicists have expressed concern that the two phase plan may lead to DUNE falling far behind its primary competition, the Hyper-Kamiokande experiment, and that Phase II may not ever be constructed. Project Manager Chris Mossey reported on

5780-460: The neutrino beam axis. The others (NDLAr and NDGar) are movable and can be shifted in the direction perpendicular to the beam to detect neutrinos at different production angles. The primary purpose is to monitor and characterize the beam as the neutrinos are created in the LBNF line, so as to make accurate predictions for interaction rates at the DUNE far detector. The project was originally started as

5865-462: The neutrino masses and the values for the magnitude and rates of oscillations between neutrino flavors. These experiments are thereby searching for the existence of CP violation in the neutrino sector; that is, whether or not the laws of physics treat neutrinos and antineutrinos differently. The KATRIN experiment in Germany began to acquire data in June 2018 to determine the value of the mass of

5950-404: The neutrinos by having opposite signs of lepton number and opposite chirality (and consequently opposite-sign weak isospin). As of 2016, no evidence has been found for any other difference. So far, despite extensive and continuing searches for exceptions, in all observed leptonic processes there has never been any change in total lepton number; for example, if the total lepton number is zero in

6035-578: The only verified detection of neutrinos from a supernova. However, many stars have gone supernova in the universe, leaving a theorized diffuse supernova neutrino background . Neutrinos have half-integer spin ( ⁠ 1  / 2 ⁠ ħ ); therefore they are fermions . Neutrinos are leptons. They have only been observed to interact through the 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

6120-409: The probability for an interaction. In general the interaction probability increases with the number of neutrons and protons within a nucleus. 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

6205-477: The project is now phased. The beamline for DUNE is called the "Long Baseline Neutrino Facility" (LBNF). The final design calls for a 2.4 MW proton beam from the Main Injector accelerator to be targeted in the LBNF beamline to produce pions and kaons that are magnetically focused into a decay pipe via a magnetic horn where they decay to neutrinos . The neutrinos will travel in a straight line through

6290-643: The project's cost to be between $ 1.26 billion to $ 1.86 billion. At the time of CD-1R, the DOE required that if the projected baseline cost rise to exceed $ 2.79 billion, or 50% above the range’s upper bound, then CD-1R must be revisited---a situation that was already being realized by 2020. In November 2021, Department of Energy (DOE) Office of Science officials reported to the High Energy Physics Advisory Panel that although DUNE had secured $ 570M in international funding at that time,

6375-688: The pure flavor states produced has been found to depend profoundly on the flavor. The relationship between flavor and mass eigenstates is encoded in the PMNS matrix . Experiments have established moderate- to low-precision values for the elements of this matrix, with the single complex phase in the matrix being only poorly known, as of 2016. A non-zero mass allows neutrinos to possibly have a tiny magnetic moment ; if so, neutrinos would interact electromagnetically, although no such interaction has ever been observed. Neutrinos oscillate between different flavors in flight. For example, an electron neutrino produced in

6460-428: The reactor experiment KamLAND and the accelerator experiments such as MINOS . The KamLAND experiment has indeed identified oscillations as the neutrino flavor conversion mechanism involved in the solar electron neutrinos. Similarly MINOS confirms the oscillation of atmospheric neutrinos and gives a better determination of the mass squared splitting. Takaaki Kajita of Japan, and Arthur B. McDonald of Canada, received

6545-947: The scientific vocabulary through Enrico Fermi , who used it during a conference in Paris in July ;1932 and at the Solvay Conference in October ;1933, where Pauli also employed it. The name (the Italian equivalent of "little neutral one") was jokingly coined by Edoardo Amaldi during a conversation with Fermi at the Institute of Physics of via Panisperna in Rome, in order to distinguish this light neutral particle from Chadwick's heavy neutron. In Fermi's theory of beta decay , Chadwick's large neutral particle could decay to

6630-454: The source of the rising costs to the 2023 Particle Physics Project Prioritization Panel at a meeting held at Fermilab in March 2023. He stated that the sources were: Apart from the project management issues identified above, one can also identify sociological issues that contributed to the rising costs: The primary competition to DUNE is the Hyper-Kamiokande (Hyper-K) experiment. Hyper-K

6715-412: 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

6800-476: The total cost of the project was at the point of triggering a CD-1R rereview, called CD-1RR. DOE reviews held in January and June 2021 concluded that even a descoped version of the project consisting of only two far detectors and a near detector would exceed the DOE upper allowed range of total project cost growth of $ 2.75B. The CD-1RR process was to establish an improved cost range and schedule by mid-2022. Due to

6885-449: The two possible spin states has ever been seen), while neutrinos were all left-handed. Antineutrinos were first detected as a result of their interaction with protons in a large tank of water. This was installed next to a nuclear reactor as a controllable source of the antineutrinos (see Cowan–Reines neutrino experiment ). Researchers around the world have begun to investigate the possibility of using antineutrinos for reactor monitoring in

6970-494: Was filled with argon in July 2015 and began data taking. The collaboration announced that they had found evidence of the first neutrino interactions in the detector in November 2015. MicroBooNE collected five years of physics data, ending its run in 2021 as the longest continually operating liquid argon time projection chamber to date. In October 2021 the results of the first three years of operation were reported. Analyses examined

7055-506: Was officially dissolved on January 30, 2015, shortly after the new collaboration recommended by P5 was formed on January 22, 2015. The new collaboration selected the name Deep Underground Neutrino Experiment (DUNE). In response to the P5 call for more international involvement, as of 2022, scientists from over 30 countries were involved in the construction of LBNF and DUNE. In 2017, the UK's Science and Technology Facilities Council (STFC) announced

7140-423: Was postulated first by Wolfgang Pauli in 1930 to explain how beta decay could conserve energy , momentum , and angular momentum ( spin ). In contrast to Niels Bohr , who proposed a statistical version of the conservation laws to explain the observed 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

7225-404: 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

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