# Review of Liquid Argon Detector Technologies in the Neutrino Sector
## 2 Single-Phase Experiments
### Sbnd  
The Short-Baseline Near Detector (SBND) is the newest LArTPC experiment at Fermilab. As its name implies, it is intended to be the near detector of the SBN Program on Fermilab's Booster Neutrino Beamline, and as such it will receive the full unoscillated contents of the beam-more than 6.5 million \(\
u_{\mu}\) events and 55,000 \(\
u_{e}\) events over three years of operation [33]. Such high statistics will allow SBND to perform high precision measurements across a wide range of topics in Neutrino Physics-including LAr interaction cross sections, the search for light and heavy sterile neutrinos, and observation of rare and non-standard interactions. The SBND LArTPC structure is shown schematically in Figure 13. Sharing a similar design to the two ICARUS T600 modules, the 4 \(\times\) 4 \(\times\) 5 m detector contains an active LAr  
Figure 12: The MicroBooNE light collection system mounted on the interior of the cryostat. The two subsystems can be seen: the primary array of 32 8-inch diameter Hamamatsu R5912-02 MOD PMTs with attached Tetra-Phenyl Butadiene (TPB)-coated acrylic disks, and the secondary set of 4 (vertically orientated) lightguide paddles. Taken from [12]. mass of 112 tonnes, and features a vertically-orientated \"cathode plane assembly\" (CPA) with two independent drift volumes positioned back-to-back and wire-based APAs located on the outer sides. The various elements of the photon detection system [34], which is once again used to directly observe the prompt scintillation light, are mounted behind the wires of the APAs. The entire LArTPC structure is suspended from the lid of the SBND membrane cryostat, as shown in Figure 14, and cosmic ray taggers comprised of multiple planes of scintillator bars surround the structure [20]. The use of a membrane cryostat instead of a more standard vacuum vessel allows SBND to act as a prototype and testing platform for the expected use of membrane cryostats by the (Proto)Deep Underground Neutrino Experiment (DUNE) single- and dual-phase detectors. The SBND CPA consists of 16 stainless steel mesh panels held in a stainless steel support frame [20]. The cathode bias-nominally of \(-100\) kV-is transferred via a high voltage feedthrough of similar design to that used by ICARUS T600, which connects to the CPA at a contact point made between the feedthrough's spring-loaded tip and a torus that is welded to the support frame. Rather than using continuous electrode loops like those employed on ICARUS T600 and MicroBooNE, the field-shaping in the SBND drift volumes is performed by a series of roll-formed aluminium profiles [20] mounted onto a structural framework positioned around the perimeter of the CPA, as shown in Figure 13. This field cage design is the same as that of the ProtoDUNE detectors, and will also be used in both the single- and dual-phase DUNE LArTPCs as well. The nominal drift field in SBND is 500 V/cm, giving a maximum drift time of 1.3 ms in each of the 2 m wide drift volumes [20]. Figure 13: The Short-Baseline Near Detector (SBND) LArTPC structure, with some of the major components labelled: the cathode plane assembly (CPA), the wire-based anode plane assemblies (APAs), the field cage and the HV-FT (high voltage feedthrough). Taken from [35]. In terms of the fundamental design, each of the SBND APAs [36] is identical to that of MicroBooNE: three parallel planes of wires denoted as U, V and Y in order of innermost to outermost, respectively orientated at angles of \(+60^{\circ}\), \(-60^{\circ}\) and \(0^{\circ}\) in relation to vertical, and with both wire-to-wire and inter-plane spacings of 3 mm. This is depicted schematically in Figure 15 (left) and photographed in Figure 15 (right). The planes are biased at \(-200\) V, \(0\) V and \(+430\) V (U, V and Y respectively) [36], once again resulting in two induction planes and one collection plane.