# Review of Liquid Argon Detector Technologies in the Neutrino Sector
## 2 Single-Phase Experiments
### DUNE (Single-Phase Far Detector)
Each front-end motherboard is designed to gather the signals from 128 wires, with 20 motherboards therefore required per APA. Cold cables will then carry the collected signals out of the cryostat through feedthroughs, with each feedthrough serving two APAs (40 motherboards). The wire biases are also provided through these feedthroughs, as are the connections to and from the PDS (described below) [47]. Additional signal processing will be performed in WIECs mounted on the external sides of the feedthroughs, before the readouts are passed to the off-detector acquisition systems. Due to the layout of the DUNE-SP drift volumes, the PDS is extremely constrained in terms of design and available hardware. Since any light-sensitive detectors must of course have an unobstructed view of the drift volumes but be located outside the volumes themselves, the PDS components must be situated within the APA frames, which are only 12 cm across [47]. This therefore rules out the use of large-diameter PMTs. At the time of writing, the final design of the DUNE-SP PDS is still to be confirmed, but two families of light collection devices are under consideration due to their size and relatively high photon detection efficiencies: (X)-ARAPUCA ([37; 38], which are to be used on SBND as previously noted) and optical lightguides (similar in concept to those in use in the MicroBooNE detector). Both of these devices will, by their very design, naturally incorporate TPB wavelength shifter, but additional visible light yield may be found (if required) by installing a TPB-coated reflective foil on the CPAs [47], much like in the LArIAT and SBND detectors. Figure 25: A completed APA, with all wire planes in place and on-frame electronics installed. This particular APA is currently installed at the single phase ProtoDUNE (ProtoDUNE-SP) (see Section 2.6), but the design is identical to that of single-phase DUNE (DUNE-SP). Taken from [47]. The light collection device that is eventually implemented in DUNE-SP must of course be coupled to a photo-sensitive detector of some nature, and studies are also underway to find and procure a device (or devices) that satisfies the DUNE-SP physics, design and operational requirements [47]. The colossal scale of the DUNE far detectors-both individually and when considered as a single experiment-will allow DUNE to study a broad range of Particle Physics topics at unparalleled high precision and with high statistics [45]. The primary focus will be the study of neutrino oscillations, including measurement of the \(\theta_{23}\) mixing angle, the neutrino mass hierarchy, and testing for the existence of sterile neutrinos. Other topics of interest include (but are by no means limited to) supernovae neutrinos, interaction cross-sections and dark matter searches. Two of the far detector modules are tentatively expected to begin operating in the late 2020s, with the remaining two modules following later as development and funding allow. The order in which the single- and dual-phase modules begin operation is not set, but will depend on the development, operation and results from ProtoDUNE-SP and ProtoDUNE-DP.