HOME

TheInfoList



OR:

The Deep Underground Neutrino Experiment (DUNE) is a
neutrino A neutrino ( ; denoted by the Greek letter ) is a fermion (an elementary particle with spin of ) that interacts only via the weak interaction and gravity. The neutrino is so named because it is electrically neutral and because its rest mass ...
experiment under construction, with a near detector at
Fermilab Fermi National Accelerator Laboratory (Fermilab), located just outside Batavia, Illinois, near Chicago, is a United States Department of Energy national laboratory specializing in high-energy particle physics. Since 2007, Fermilab has been oper ...
and a far detector at the
Sanford Underground Research Facility The Sanford Underground Research Facility (SURF), or Sanford Lab, is an underground laboratory in Lead, South Dakota. The deepest underground laboratory in the United States, it houses multiple experiments in areas such as dark matter and neutrino ...
that will observe neutrinos produced at
Fermilab Fermi National Accelerator Laboratory (Fermilab), located just outside Batavia, Illinois, near Chicago, is a United States Department of Energy national laboratory specializing in high-energy particle physics. Since 2007, Fermilab has been oper ...
. An intense beam of trillions of neutrinos from the production facility at Fermilab (in
Illinois Illinois ( ) is a state in the Midwestern United States. Its largest metropolitan areas include the Chicago metropolitan area, and the Metro East section, of Greater St. Louis. Other smaller metropolitan areas include, Peoria and Rock ...
) will be sent over a distance of with 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 *Investigation of neutrino oscillations to test
CP violation In particle physics, CP violation is a violation of CP-symmetry (or charge conjugation parity symmetry): the combination of C-symmetry (charge symmetry) and P-symmetry ( parity symmetry). CP-symmetry states that the laws of physics should be t ...
in the
lepton In particle physics, a lepton is an elementary particle of half-integer spin (spin ) that does not undergo strong interactions. Two main classes of leptons exist: charged leptons (also known as the electron-like leptons or muons), and neutr ...
sector, which explores why the universe is made of matter *Determination the ordering of the neutrino masses, which asks "which neutrino is lightest?"; *Studies of
supernova A supernova is a powerful and luminous explosion of a star. It has the plural form supernovae or supernovas, and is abbreviated SN or SNe. This transient astronomical event occurs during the last evolutionary stages of a massive star or whe ...
e and the formation of a
neutron star A neutron star is the collapsed core of a massive supergiant star, which had a total mass of between 10 and 25 solar masses, possibly more if the star was especially metal-rich. Except for black holes and some hypothetical objects (e.g. w ...
or
black hole A black hole is a region of spacetime where gravity is so strong that nothing, including light or other electromagnetic waves, has enough energy to escape it. The theory of general relativity predicts that a sufficiently compact mass can def ...
, even though the detector is deep underground with no direct view of the sky; *Search for
proton decay In particle physics, proton decay is a hypothetical form of particle decay in which the proton decays into lighter subatomic particles, such as a neutral pion and a positron. The proton decay hypothesis was first formulated by Andrei Sakharov ...
, which has never been observed but is predicted by theories that unify the fundamental forces. The science goals were sufficiently compelling in 2014 that the
Particle Physics Project Prioritization Panel The Particle Physics Project Prioritization Panel (P5) is a scientific advisory panel tasked with recommending plans for U.S. investment in particle physics research over the next ten years, on the basis of various funding scenarios. The P5 is a t ...
(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 the
Hyper-Kamiokande Hyper-Kamiokande is a neutrino observatory being constructed on the site of the Kamioka Observatory, near Kamioka, Japan. The project started in 2010 as a successor to Super-Kamiokande. It was ranked as among the 28 top priority projects of the Ja ...
experiment in Japan, scheduled to begin data-taking in 2027. The DUNE project, overseen by
Fermilab Fermi National Accelerator Laboratory (Fermilab), located just outside Batavia, Illinois, near Chicago, is a United States Department of Energy national laboratory specializing in high-energy particle physics. Since 2007, Fermilab has been oper ...
, has suffered delays to its schedule and growth of cost from less than $2B to $3B, leading to articles in the journals ''Science'' and ''Scientific American'' described the project as "troubled." In 2022, the DUNE experiment had a neutrino-beam start-date in the early-2030's, and the project is now phased.


Design of LBNF/DUNE


The Long Baseline Neutrino Facility

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 Fermi National Accelerator Laboratory (Fermilab), located just outside Batavia, Illinois, near Chicago, is a United States Department of Energy national laboratory specializing in high-energy particle physics. Since 2007, Fermilab has been opera ...
accelerator to be targeted in the LBNF beamline to produce
pions In particle physics, a pion (or a pi meson, denoted with the Greek letter pi: ) is any of three subatomic particles: , , and . Each pion consists of a quark and an antiquark and is therefore a meson. Pions are the lightest mesons and, more gene ...
and
kaons KAON (Karlsruhe ontology) is an ontology infrastructure developed by the University of Karlsruhe and the Research Center for Information Technologies in Karlsruhe. Its first incarnation was developed in 2002 and supported an enhanced version of ...
that are magnetically focused into a decay pipe via a
magnetic horn A magnetic horn or neutrino horn (also known as the Van der Meer horn) is a high-current, pulsed focusing device, invented by the Dutch physicist Simon van der Meer in CERN, that selects pions and focuses them into a sharp beam. The original applic ...
where they decay to neutrinos. The neutrinos will travel in a straight line through the Earth, reaching about 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 is integral to the "improved tritium management
hat is A hat is a head covering which is worn for various reasons, including protection against weather conditions, ceremonial reasons such as university graduation, religious reasons, safety, or as a fashion accessory. Hats which incorporate mecha ...
a major focus on the design of this new, higher beam power facility." Tritium produced by beamlines at can enter the surface ground water, however rates at Fermilab are maintained at a level well below that allowed by regulations.


Dependence of LBNF on the PIP II project

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 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

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 a total volume of 70-kilotons of liquid
argon Argon is a chemical element with the symbol Ar and atomic number 18. It is in group 18 of the periodic table and is a noble gas. Argon is the third-most abundant gas in Earth's atmosphere, at 0.934% (9340 ppmv). It is more than twice a ...
located deep underground, 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 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 European Organization for Nuclear Research, known as CERN (; ; ), is an intergovernmental organization that operates the largest particle physics laboratory in the world. Established in 1954, it is based in a northwestern suburb of Gen ...
. 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 the experiments are referred to as part of the Neutrino Platform in the laboratory's research programme. The
MicroBooNE MicroBooNE is a liquid argon time projection chamber (LArTPC) at Fermilab in Batavia, Illinois. It is located in the Booster Neutrino Beam (BNB) beamline where neutrinos are produced by colliding protons from Fermilab's booster-accelerator on a b ...
experiment and
ICARUS experiment ICARUS (Imaging Cosmic And Rare Underground Signals) is a physics experiment aimed at studying neutrinos. It was located at the Laboratori Nazionali del Gran Sasso (LNGS) where it started operations in 2010. After completion of its operations there ...
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 MicroBooNE is a liquid argon time projection chamber (LArTPC) at Fermilab in Batavia, Illinois. It is located in the Booster Neutrino Beam (BNB) beamline where neutrinos are produced by colliding protons from Fermilab's booster-accelerator on a b ...
is the longest continuously running LArTPC detector, having taken data from 2015 to 2021—a considerably shorter than time-period than the 20 years required for DUNE.


The DUNE near detector

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 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.


History leading to the international collaboration

The project was originally started as 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 The Particle Physics Project Prioritization Panel (P5) is a scientific advisory panel tasked with recommending plans for U.S. investment in particle physics research over the next ten years, on the basis of various funding scenarios. The P5 is a t ...
(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 Fermi National Accelerator Laboratory (Fermilab), located just outside Batavia, Illinois, near Chicago, is a United States Department of Energy national laboratory specializing in high-energy particle physics. Since 2007, Fermilab has been oper ...
as host". The LBNE collaboration 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 a £65M investment in DUNE and LBNF. By 2022, the international partners providing in-kind contributions also included
CERN The European Organization for Nuclear Research, known as CERN (; ; ), is an intergovernmental organization that operates the largest particle physics laboratory in the world. Established in 1954, it is based in a northwestern suburb of Gen ...
, Brazil, Switzerland and Poland and the total foreign contribution to the $3B project was $570M, or about 20%.


Revisions to Scope, Cost and Schedule

The original scope and cost for 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 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 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 The High Energy Physics Advisory Panel (HEPAP) is a permanent advisory committee to the United States Department of Energy and the National Academy of Sciences, created in 1967 and organized under the Federal Advisory Committee Act The Federal Advi ...
that although DUNE had secured $570M in international funding, 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 a history of lower-than-requested congressional appropriations for the project, at the same November 2021 meeting, DOE presented a "conservative profile
or funding Or or OR may refer to: Arts and entertainment Film and television * "O.R.", a 1974 episode of M*A*S*H * Or (My Treasure), a 2004 movie from Israel (''Or'' means "light" in Hebrew) Music * ''Or'' (album), a 2002 album by Golden Boy with Miss ...
that the Office of Science can support." In March, 2022, DOE announced that the project would be completed in two phases. The plan for phasing was announced during the
Snowmass Process The Snowmass Process is a particle physics community planning exercise sponsored by the Division of Particles and Fields of the American Physical Society. During this process, scientists develop a collective vision for the next seven to ten years ...
, an exercise periodically organized by 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 $3B.1 cost. However, the project schedule indicates that far detector module 2 will only be 40% filled with liquid argon at project completion, and therefore not immediately useable for physics. In addition to the $3.1B cost to the US, which does not include the cost of the PIP II upgrade that is required for DUNE, the project is promised about from international partners. Therefore, the cost for Phase I of LBNF/DUNE to reach its physics goal is close to $5B. Phase II would complete the full scope by adding the additional two far modules, completing the suite of subdetectors at 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. The LBNF/DUNE project was reviewed throughout 2022. However, at the end of 2022, it was announced that the necessary approval from the DOE Energy Science Aquisition Advisory Board would occur in 2023. The delay in approval partially reflects fact that the $3.1B cost estimate was made in 2021, prior to the steep rise in inflation in 2022 and before delays due to the Covid-19 pandemic could be fully assessed. Physicists expressed concern that the two phase plan may lead to DUNE falling far behind its primary competition, the
Hyper-Kamiokande Hyper-Kamiokande is a neutrino observatory being constructed on the site of the Kamioka Observatory, near Kamioka, Japan. The project started in 2010 as a successor to Super-Kamiokande. It was ranked as among the 28 top priority projects of the Ja ...
experiment, and that Phase II may not ever be constructed.


Stiff Competition with Hyper-K and Other Experiments

The primary competition to DUNE is the
Hyper-Kamiokande Hyper-Kamiokande is a neutrino observatory being constructed on the site of the Kamioka Observatory, near Kamioka, Japan. The project started in 2010 as a successor to Super-Kamiokande. It was ranked as among the 28 top priority projects of the Ja ...
(Hyper-K) experiment. Hyper-K is a 260 kton total volume detector under construction 295 km from the Japan Proton Accelerator Research Complex (
J-PARC J-PARC (Japan Proton Accelerator Research Complex) is a high intensity proton accelerator facility. It is a joint project between KEK and JAEA and is located at the Tokai campus of JAEA. J-PARC aims for the frontier in materials and life scienc ...
) neutrino source. Construction is estimated to be completed by 2028. 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, 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 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 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 the JUNO experiment in China and as 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 the liquid argon technology than can be achieved in the water-based Hyper-K water detector.


Construction at the Sanford Underground Research Facility

The
Sanford Underground Research Facility The Sanford Underground Research Facility (SURF), or Sanford Lab, is an underground laboratory in Lead, South Dakota. The deepest underground laboratory in the United States, it houses multiple experiments in areas such as dark matter and neutrino ...
makes use of, and is extending, the facilities of the
Homestake Mine (South Dakota) The Homestake Mine was a deep underground gold mine (8,000 feet or 2,438 m) located in Lead, South Dakota. Until it closed in 2002 it was the largest and deepest gold mine in North America. The mine produced more than of gold during its lifetime ...
, which ceased operations at the end of 2001, to accommodate the far detector modules. Excavation of the DUNE far detector cavities began on July 21, 2017. Rock removed from underground is deposited in the Open Cut in the center of the city of
Lead, South Dakota Lead ( ) is a city in Lawrence County, South Dakota, United States. The population was 2,982 at the 2020 census. Lead is located in western South Dakota, in the Black Hills near the Wyoming state line. History The city was officially founded ...
. Project management for the construction is overseen by Fermilab. In June 2021, plumes of dust rising from 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 the Open Cut. With these assurances in place, Fermilab was allowed to resume rock dumping on April 8, 2022.


References


External links

* {{Neutrino detectors Accelerator neutrino experiments Neutrino experiments Fermilab experiments International science experiments Fixed-target experiments