06.02.2023

DUNE Collaboration Meeting Held at CERN

In late January 2023, CERN, the European Organization for Nuclear Research, hosted the meeting of the collaboration of the mega-science project DUNE. It was attended by scientists from the Experimental Department of Particle Physics of the Dzhelepov Laboratory of Nuclear Problems (EDPP of DLNP). At the meeting, the project status and different scenarios of accelerator upgrade to achieve desired results at the earliest possible date were considered. Also, plans were vividly discussed for processing and analyzing the first data from the prototype of one of the DUNE near-detector complex facilities at the Fermi National Accelerator Laboratory (Fermilab, USA), and also the data from the prototype far detector at CERN accumulated over previous years.

DUNE is a next-generation (anti)neutrino accelerator experiment being constructed with the aim to refine neutrino oscillation parameters and measure those still unknown. Its main objectives are measuring the neutrino mass ordering and CP invariance violation in the lepton sector. Thus, it continues the experimental programmes of currently ongoing NOvA (the USA) and T2K (Japan). DUNE will be dealing with muon (anti)neutrinos produced at the Fermilab accelerator complex as a result of interaction between the ejected proton beam and fixed target. Neutrinos produced in this way will have to cover a distance of 1300 km. There they will be recorded at the Sanford Underground Research Facility (the USA) with a 70-kt far detector. After covering this distance, the beam composition will change due to oscillations. The control measurement of the initial neutrino beam will be taken at the near detector complex consisting of three facilities. The first one, the ND-LAr (Near Detector Liquid Argon), is a modular liquid-argon time projection chamber similar in methodology to the far detector. The second detector, the ND-GAr (Near Detector Gaseous Argon), will be located close to the first one. This is a gas time projection high-pressure chamber located inside the magnet, which will allow determining the lepton charge and momentum during neutrino interaction inside the ND-LAr. Both detectors will be placed on the movable platform in order to measure the beam composition at a distance of up to 33 m away from the axis (DUNE−PRISM concept). The third facility of the DUNE near-detector complex, SAND (System for on-Axis Neutrino Detection), a straw-tube tracker (STT) inside the solenoid magnet of the KLOE experiment (Frascati, Italy), will be fixed on the beam axis. The DUNE physics programme is multifaceted due to various detecting methods and goes beyond the mere measurement of neutrino oscillation parameters.

The workshop on the analysis of ND-LAr prototype data was held at the University of Bern on 19−21 January in advance of the collaboration meeting. During this year, four scaled-down ND-LAr modules are planned to be installed in the cryostat at Fermilab, along with plastic scintillator cell modules of the MINERvA experiment with the neutrino beam intended for the NOvA experiment. Apart from methodological research, this prototype will be used to solve physics problems, such as measurements of neutrino interaction cross sections, charged particle multiplicity and others. The full-sized ND-LAr will contain 35 modules. The EDPP group is responsible for development of the ND-LAr light readout system and is involved in testing and assembling the modules at the University of Bern.

At present, the construction is going on at the Sanford research centre – the far-detector underground hall and the laboratory are half-completed. The DUNE experiment will start operating with two far-detector modules. The proton beam power planned for the launch is 1.2 MW. Due to the complexity of the ND-GAr manufacture, it will be temporarily replaced first with The Muon Spectrometer (TMS) made of scintillator with iron layers. At the next stage, two other far-detector modules will be installed, ND-GAr assembled and the accelerator upgraded to the beam power of 2.4 MW. The SAND facility will ensure a reliable monitoring of the neutrino beam, allow its flux and energy spectrum shape to be measured during a short time. In addition, the detector structure of thin layers of graphite (C) and polypropylene (CH₂) will ensure the measurement of cross sections of neutrino interactions (and other processes) on the hydrogen target free of intranuclear interactions using the subtraction method. Already during the first years of DUNE operation, it will be possible to measure the neutrino mass ordering. It will take longer to accumulate statistics to measure the CP violation phase.

The experiment is being prepared with participation of specialists from several subdivisions of our Institute. EDPP scientists not only contribute methodologically but also perform simulations, develop reconstruction and DUNE data analysis programmes. At CERN, at the test bench developed by LHEP specialists for the SAND detector, methodological work with straw tubes is being conducted. MLIT specialists are developing computational infrastructure for data storage and processing.

This comprehensive professional contribution makes JINR staff participation in the DUNE project especially valuable and noticeable for collaboration.

Meeting attendees
from the DLNP Experimental Department of Particle Physics

EDPP specialists, attendees of the workshop on the ND-LAr prototype at the University of Bern | Credits: Alexander Selyunin

Nikolay Anfimov and Alexander Selyunin (DLNP of JINR) at the University of Bern near the time projection chamber module placed in the cryostat. This module will turn part of the ND-LAr prototype at Fermilab | Credits: Liudmila Kolupaeva

Collective photo of attendees of the workshop held on 19−21 January at the University of Bern on the ND-LAr prototype | Credits: from the personal archive of ND-LAr consortium members