ProtoDUNE-SP

ProtoDUNE-SP
Name	ProtoDUNE Single-Phase
Location	CERN, Geneva
Facility	CERN Neutrino Platform
Detector type	Liquid argon time projection chamber
Volume	780 m³
Start	2018
Collaboration	DUNE collaboration, CERN

ProtoDUNE-SP is a large-scale prototype liquid argon time projection chamber constructed at the CERN Neutrino Platform in the EIROforum framework to demonstrate technologies for the Deep Underground Neutrino Experiment and to validate designs for the Long-Baseline Neutrino Facility. The project brought together institutions from the DUNE collaboration, Fermilab, SLAC National Accelerator Laboratory, Brookhaven National Laboratory, and universities such as University of Oxford, University of Geneva, and University of California, Berkeley. The prototype operated in the North Area, CERN test beam area to study detector response to charged particles relevant for neutrino oscillation measurements and supernova neutrino detection.

Background and objectives

The initiative originated from planning activities within the DUNE collaboration and the Neutrino Physics community to mitigate technical risk for the Long-Baseline Neutrino Facility far detector modules to be sited at the Sanford Underground Research Facility. Goals included demonstrating electron lifetime and argon purity achievable in large cryostats, validating high-voltage delivery and field cage stability, and testing readout electronics and data acquisition systems developed by groups at Fermilab and Brookhaven National Laboratory. ProtoDUNE-SP also aimed to provide calibration samples using charged pions, protons, kaons and muons from the CERN SPS test beams and to exercise software stacks from collaborations such as LArSoft and reconstruction frameworks used by DUNE collaboration and ICARUS teams.

Detector design and components

The prototype implemented a single-phase liquid argon time projection chamber concept with an active volume instrumented by Anode Plane Assemblies fabricated by consortia including University of Manchester and Università di Padova. Ionization electrons drifted under an electric field provided by a high-voltage system designed by Fermilab engineers, with a cathode and modular field cage panels developed with input from Lawrence Berkeley National Laboratory and Stanford University (Stanford). Charge readout used cold electronics instruments based on ASIC designs from Brookhaven National Laboratory and SLAC National Accelerator Laboratory; photon detection systems employed wavelength-shifting bars and silicon photomultipliers supplied by groups at Colorado State University and TRIUMF. Cryostat and cryogenics infrastructure were provided by industrial partners under coordination by CERN cryogenics teams, while purity monitors and recirculation pumps incorporated designs tested at Gran Sasso National Laboratory and Fermilab. The detector control systems integrated software from CERN and Fermilab operations groups.

Construction and commissioning

Assembly took place in the EHN1 experimental hall at CERN with mechanical engineering contributions from Cavendish Laboratory, ETH Zurich, and industrial vendors experienced with cryostat fabrication. Key milestones included installation of Anode Plane Assemblies, cathode panels, field cage modules, and immersion of cold electronics in liquid argon. Commissioning sequences validated cryogenics, purification, and high-voltage systems, with assistance from teams at Fermilab and Brookhaven National Laboratory and instrumentation specialists from CERN and SLAC National Accelerator Laboratory. Safety reviews involved regulatory bodies such as the European Organization for Nuclear Research safety committees and local Geneva authorities. Initial cool-down and argon fill operations followed procedures developed with input from SNOLAB and Sanford Underground Research Facility engineers to ensure thermal gradients and material compatibility.

Test beam operations and data collection

ProtoDUNE-SP received charged particle beams from the CERN Super Proton Synchrotron (SPS) providing hadron and muon beams in momentum ranges relevant for DUNE reconstruction. Beam instrumentation included Cherenkov counters, time-of-flight systems, and wire chambers supplied by collaborations with the CERN NA61/SHINE teams and universities such as University of Birmingham and University of Sheffield. Data acquisition integrated readout electronics tested by Fermilab and Brookhaven National Laboratory teams and recording to storage systems coordinated with CERN IT and the Worldwide LHC Computing Grid. Physics runs yielded samples of pions, kaons, protons and muons for calorimetry, particle identification, and cross-section studies used by analysis groups from University of Oxford, University of Manchester, University of California, Berkeley, University of Texas at Austin, and University of Pennsylvania.

Calibration, reconstruction, and analysis

Calibration efforts combined cosmic-ray muon datasets, test-beam tagged samples, and deployed pulser systems to tune energy scale, electron lifetime, and drift-velocity measurements. Reconstruction software used the LArSoft framework alongside pattern-recognition algorithms developed by teams at Argonne National Laboratory, Lawrence Berkeley National Laboratory, and SLAC National Accelerator Laboratory. Analyses included studies of electron recombination, charge attenuation, space-charge effects known from MicroBooNE experience, and photon detection timing performance in collaboration with groups from Columbia University and MIT. Systematic studies engaged statisticians and software engineers from Fermilab and CERN to validate simulation chains based on GEANT4 and generator inputs from GENIE and hadron-production data from NA61/SHINE.

Results and impact on DUNE design

ProtoDUNE-SP demonstrated sustained electron lifetimes and argon purity consistent with requirements for the DUNE far detector modules, validated high-voltage delivery schemes, and informed choices for Anode Plane Assembly production and cold electronics strategies coordinated by Fermilab and Brookhaven National Laboratory. Operational experience influenced cryostat procurement, safety practices adopted for the Sanford Underground Research Facility installations, and reconstruction requirements for oscillation and supernova neutrino analyses pursued by the DUNE collaboration. The prototype produced public performance results that guided funding and technical decisions involving agencies such as the U.S. Department of Energy, European Research Council, and national laboratories including Fermilab and Brookhaven National Laboratory, while providing a training ground for students and postdocs from institutions like University of Oxford, University of Geneva, and University of California, Berkeley.

Category:Particle detectors Category:Neutrino experiments