Developments Towards a νe CC Sterile Appearance Sensitivity in the Short-Baseline Neutrino Programme

The Short Baseline Neutrino (SBN) programme is an upcoming neutrino experiment situated on the Booster Neutrino Beam (BNB) at the Fermilab National Laboratory. One of the primary objectives of the SBN programme is to confirm or refute the low energy electron neutrino excess observed in previous neutrino experiments: LSND and MiniBooNE. It was postulated that this observed low energy electron neutrino excess was caused by the existence of one or more sterile neutrinos. If this is confirmed, it will alter our current understanding of physics as well as the standard model and the prescription of neutrino oscillations.

To achieve this primary objective, the SBN programme will perform studies which are sensitive to electron neutrino appearances. These are carried out assuming several sterile models, in particular the 3+1 model. To undertake the physics goals of the SBN programme, three Liquid Argon Time Projection Chambers (LArTPCs) are positioned at various points along the BNB beamline. These LArTPCs are known as The Short Baseline Near Detector (SBND) (110 m), Micro Booster Neutrino Experiment (MicroBooNE) (470 m), and the Imaging Cosmic And Rare Underground Signals (ICARUS) (600 m) detector. LArTPCs provide sophisticated calorimetric and topological information to identify the energy and flavour of charged particles in neutrino interactions. For an electron neutrino excess search, it is important to reconstruct and identify the resultant electron from neutrino Charge Current (CC) events. A new framework with new methods was developed to characterise electromagnetic showers to help identify electrons from background photon showers. The new methods were then employed in an oscillated electron neutrino selection upon simulated events in the SBN detectors. The resultant event distributions were then used to perform an electron neutrino appearance sensitivity analysis using the 3 + 1 sterile model in the VALencia-Oxford-Rutherford (VALOR) neutrino oscillation fitting framework.

The single-phase wire near detector of the SBN programme, SBND, is also viewed as a prototype for the upcoming Deep Underground Neutrino Experiment (DUNE) far detector. Due to the high rate of events at the location of the DUNE near detector, single-phase wire LArTPCs are not feasible. Therefore, alternative readout methods are being considered, such as a pixelated readout. To test these alternative readout methods, a research rig at the University of Sheffield has been developed.