The DUNE Far Detector
The DUNE collaboration will use state-of-the-art Liquid Argon Time-Projection Chamber (LArTPC) technology for the massive — but extremely sensitive — neutrino detector planned at the Sanford Lab site, called the DUNE Far Detector. This detector will be constructed and operated almost a mile (1.5 km) underground. Cosmic ray muons, which constantly bombard Earth’s surface, would generate tracks in the detector if it were at the surface, complicating the data analysis. The large amount of rock above the Far Detector will absorb virtually all the incident cosmic rays before they reach the DUNE Far Detector.
The detector is planned to consist of four separate modules to be installed in two long caverns. Groundbreaking for the excavation of the caverns took place in July 2017. The detector modules will hold a combined total of 68,000 tons of liquid argon (LAr), which is the target material for neutrino interactions. Argon, a gas at room temperature, condenses to a liquid when cooled below -186°C (-303°F) and requires containment in well insulated cryostats and a sophisticated cooling infrastructure.
Within the fluid volume of each cryostat, neutrino interactions with argon atoms will produce ionization electrons that drift under the influence of a high-voltage electric field to detection elements that are either fully or partially immersed in the LAr, depending on the design: single-phase (fully immersed in LAr) or dual-phase (immersed partially in LAr, partially in gaseous argon). DUNE plans to construct the first module using the single-phase technology, with the choice for the other detectors coming at a later time.
The four 17,000-ton DUNE Far Detector modules will comprise by far the largest liquid argon neutrino detector ever built. The DUNE collaboration is pursuing an aggressive program of building and testing detector components in preparation for Far Detector construction.
DUNE’s single-phase ProtoDUNE detector will consist of a small number of full-scale components of the single-phase Far Detector module design. DUNE’s dual-phase ProtoDUNE detector will test an innovative modification of LArTPC technology in preparation for use in the Far Detector module. This prototype detector features signal amplifiers that operate in a layer of gaseous argon above the volume of liquid argon. This detector is preceded by the construction and operation of a smaller, 25-ton dual-phase prototype detector, also at CERN, in 2016-17.
The DUNE Near Detector
A design effort is underway for a fine-grained neutrino detector, referred to as the DUNE Near Detector, to be located at Fermilab a few hundred meters downstream of the neutrino source powered by the accelerator complex at Fermilab.
This detector’s principal role is to characterize the neutrino beam in its initial state — before it travels 800 miles (1,300 km) to the far site — in order to better understand the signals collected at the Far Detector, and thus to maximize the neutrino oscillation physics potential of the DUNE experiment. In addition, the Near Detector will enable a rich program of particle physics measurements independent of the Far Detector and provide the data for many PhD theses.
The Near Detector design is not yet finalized.