HPTPC - A High-Pressure Time Projection Chamber for Neutrino Physics

The precise characterisation of neutrino-nuclei interactions is vital for future long baseline neutrino experiments to meet their sensitivity goals. A time projection chamber (TPC) filled with a high-pressure gas is an ideal detector for making these measurements. Such a detector could achieve a lower energy threshold than a liquid or solid detector, while also allowing more neutrino events to be recorded than would be in a gas TPC operated at atmospheric pressure. High-pressure gas TPCs are also promising detectors for characterising neutrino beams in long baseline neutrino experiments. For this reason, the 2021 Deep Underground Neutrino Experiment (DUNE) near detector (ND) conceptual design report (CDR) includes a design for a high-pressure gas TPC as part of the DUNE ND complex. This thesis covers two high-pressure TPC set-ups which were operated at Royal Holloway, University of London between 2018 and 2022. The first half of the thesis covers the commissioning of a transparent TPC with hybrid optical and charge gain readout, based on the DMTPC (Dark Matter Time Projection Chamber) experiment. The second half investigates the suitability of multiwire proportional chambers (MWPCs) taken from the ALICE TPC for use as the readout chambers of a high-pressure gas TPC in the DUNE
ND. It reports the successful operation of an ALICE TPC outer readout chamber (OROC) at pressures so far up to 4 bar absolute with Ar-CH4 and Ar-CO2 gas mixtures. From these results, a study into the expected ability of the high-pressure TPC design from the DUNE ND CDR concludes that, given some further study, the TPC may be capable of reconstructing and separating final states by pion multiplicity with an efficiency of at least 70 %. This is a significant improvement to the reconstruction capabilities of the ND; without a high-pressure TPC, final states containing multiple pions would be expected to be correctly reconstructed only 50 % of the tim