ArgonCube paving the way to a near site LArTPC

The test TPC used for the meaurements with cosmic ray muons. Photo: LHEP, University of Bern

Spearheaded by the Laboratory for High Energy Physics at the University of Bern and made up of existing DUNE member institutions, ArgonCube is a collaboration for LArTPC detector R&D, with a focus on the technical needs for the DUNE physics program.  ArgonCube emerged from the earlier ArgonTube effort, which studied LArTPCs with long drift distances at high drift fields and achieved what is to date the longest drift length  —  5 m at about 1 kV/cm.

DUNE’s current plans include a LArTPC component in the Near Detector, but the high-intensity environment of the DUNE near site would pose problems for a standard LArTPC.  ArgonCube innovations can solve them.

The ArgonCube R&D program is currently pursuing detector modularization, pixelated charge readout, and new light detection techniques.  Modularization addresses issues such as drift field stability, stored energy, and liquid argon purity.  Pixelated readout has the potential to provide true 3D imaging of particle interactions, removing the ambiguities present in current readout techniques.  New approaches to light detection could increase photon yields and improve the localization of light signals.  ArgonCube has made excellent progress on all these fronts.

The ArcLight light detection technique, using dichroic and reflective films, shows high efficiency and enables instrumentation of the field cage walls.  More recently, a new approach for the LArTPC field cage, relying on thin resistive film, has yielded positive results.

In 2016 the collaboration demonstrated the feasibility of pixelated readout using a 60-cm-drift pixel TPC located at Bern.  LArIAT operated a scaled-up version of this readout technique (also known as PixLAr) at a Fermilab test beam in 2017.  In parallel, the LArPix effort at LBNL developed new cryogenic electronics to enable complete instrumentation for pixelated readout.  The success of LArPix prototype has led to a DOE Early Career Award to Dan Dwyer of LBNL to further develop the innovative readout technology.

Some members of the ArgonCube collaboration during the most recent meeting in Bern. Photo: LHEP, University of Bern

The next step in the ArgonCube program is the design and construction of a mid-scale (1.4 m by 1.4 m by 1.2 m) modular LArTPC, called the ArgonCube 2×2 Demonstrator.  Its four modules will serve as a test bed for techniques in TPC modularity and also as demonstrators for the scalability of the new charge and light detection systems.  The goal is to move the 2×2 Demonstrator to Fermilab, with the intent to operate it in the NuMI beam as a “Near Detector ProtoDUNE.”

Lessons learned from this program could lead to enhancements for the DUNE Far Detector, too. ArgonCube presented a proposal to DUNE at the May collaboration meeting to adopt the technologies it is developing for the fourth DUNE Far Detector module.