The ProtoDUNE experiment is a prototype for

DUNE A dune is a landform composed of wind- or water-driven sand. It typically takes the form of a mound, ridge, or hill. An area with dunes is called a dune system or a dune complex. A large dune complex is called a dune field, while broad, flat ...

in development by

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 Meyrin, western suburb of Gene ...

, which will measure

neutrino A neutrino ( ; denoted by the Greek letter ) is an elementary particle that interacts via the weak interaction and gravity. The neutrino is so named because it is electrically neutral and because its rest mass is so small ('' -ino'') that i ...

interactions with target atoms. DUNE will use a liquid-

argon Argon is a chemical element; it has 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 as abu ...

time projection chamber In physics, a time projection chamber (TPC) is a type of particle detector that uses a combination of electric fields and magnetic fields together with a sensitive volume of gas or liquid to perform a three-dimensional reconstruction of a particle ...

as a target for these neutrinos, also known as a LArTPC. Neutrino collisions knock

electrons The electron (, or in nuclear reactions) is a subatomic particle with a negative one elementary charge, elementary electric charge. It is a fundamental particle that comprises the ordinary matter that makes up the universe, along with up qua ...

off of

atoms Atoms are the basic particles of the chemical elements. An atom consists of a nucleus of protons and generally neutrons, surrounded by an electromagnetically bound swarm of electrons. The chemical elements are distinguished from each other ...

in the LArTPC and release

light energy In physics, and in particular as measured by radiometry, radiant energy is the energy of electromagnetic and gravitational radiation. As energy, its SI unit is the joule (J). The quantity of radiant energy may be calculated by integrating radian ...

, both of which can be measured by ProtoDUNE. Scientists use a negatively-charged

anode An anode usually is an electrode of a polarized electrical device through which conventional current enters the device. This contrasts with a cathode, which is usually an electrode of the device through which conventional current leaves the devic ...

plane array (APA) to attract and record the path of the electrons, thereby recording information about the collision itself. The ProtoDUNE detector is around the size of a three-storey house, and the DUNE project will use modules twenty times the size of ProtoDUNE. ProtoDUNE was successfully tested in 2018; as of 2023 it is the largest LArTPC ever constructed. Two detectors have been built at the neutrino platform, each containing around 800 metric tons of liquid argon. A

cryostat A cryostat (from ''cryo'' meaning cold and ''stat'' meaning stable) is a device used to maintain low cryogenic temperatures of samples or devices mounted within the cryostat. Low temperatures may be maintained within a cryostat by using various ...

is used to insulate the detector, which needs to be kept at temperatures of -184°C (-300°F) for the argon to remain liquid.

Construction

It took two years to build the first ProtoDUNE detector, and another eight weeks to fill it with 800 tons of liquid argon. Originally, one detector was built to be single-phase (ProtoDUNE-SP), using only liquid argon, while the other was built to be dual-phase (ProtoDUNE-DP), using both liquid and gaseous argon. The goal of the prototypes is to solve any engineering problems that DUNE might face before construction begins. A group led by Bob Paulos in the

University of Wisconsin–Madison The University of Wisconsin–Madison (University of Wisconsin, Wisconsin, UW, UW–Madison, or simply Madison) is a public land-grant research university in Madison, Wisconsin, United States. It was founded in 1848 when Wisconsin achieved st ...

Physical Sciences Lab designed the APA for the single-phase detector, and the APAs were built by the UW–Madison group and the Science and Technology Facilities Council’s

Daresbury Laboratory Daresbury Laboratory is a scientific research laboratory based at Sci-Tech Daresbury campus near Daresbury in Halton, Cheshire, England. The laboratory began operations in 1962 and was officially opened on 16 June 1967 as the Daresbury Nuclea ...

. In addition, CERN designed a cathode plane that would repel electrons. The dual-phase detector operated similarly, but with a slightly different array configuration. Although DUNE's neutrinos will be provided by the Long-Baseline Neutrino Facility, CERN expanded their existing network to use a particle beam to test the detectors. The beam window system that allowed researchers to test ProtoDUNE was designed, fabricated, and installed by the Department of Energy's

Lawrence Berkeley National Laboratory Lawrence Berkeley National Laboratory (LBNL, Berkeley Lab) is a Federally funded research and development centers, federally funded research and development center in the Berkeley Hills, hills of Berkeley, California, United States. Established i ...

Testing

In 2018, ProtoDUNE recorded its first particle tracks. In 2020, researchers published a paper regarding the testing of the ProtoDUNE-SP detector. They used an 800-

GeV In physics, an electronvolt (symbol eV), also written electron-volt and electron volt, is the measure of an amount of kinetic energy gained by a single electron accelerating through an electric potential difference of one volt in vacuum. When us ...

beam of

protons A proton is a stable subatomic particle, symbol , H+, or 1H+ with a positive electric charge of +1 ''e'' ( elementary charge). Its mass is slightly less than the mass of a neutron and approximately times the mass of an electron (the pro ...

and electrons from CERN's SPS accelerator to test the capabilities of the ProtoDUNE-SP detector. In the test, the results from ProtoDUNE-SP were cross-checked with those from particle detectors located just before the detector. ProtoDUNE uses reconstruction software to differentiate an actual interaction from noise. This test revealed that the detector had a signal-to-noise ratio of fifty to one and that over 99% of the detector channels were working properly. As of 2023, CERN is building ProtoDUNE II, which will include a vertical drift detector (ProtoDUNE-VD). ProtoDUNE II will contain four APAs and light sensors.

References

{{reflist CERN experiments Neutrino experiments Lawrence Berkeley National Laboratory