The Past, Present And Future Of Neutrino Near Detectors

This thesis covers two accelerator-driven long-baseline neutrino experiments. The Tokai-to-Kamioka (T2K) experiment uses a 0.6 GeV neutrino beam produced at the J-PARC beamline in Tokai, Japan to measure neutrino oscillation parameters. These parameters can be found by comparing the neutrino interaction rates at the ND280 near detector and the Super-Kamiokande far detector at 280 meters and 295 kilometers from the neutrino beam source, respectively. Accurately measuring these interaction rates and subsequently the oscillation probability is limited by the systematic uncertainties associated with the neutrino-nucleus interaction cross-sections. Hence, these interactions are studied in the high event rate environment of the ND280 near detector.

In muon-neutrino-induced charged-current single positive pion production on hydrocarbon, both a muon and a positively charged pion are produced in the final state. The four dimensional differential cross-section for this process has been measured in muon and pion kinematic parameters for the full solid angle in the past, but has always been statistically limited. Here it is presented with the full available statistics including the use of pion properties derived from Michel electrons of their subsequent decay, which improved the statistics for pion momenta between 50-400 MeV by 50%. The cross-section extraction is done with a binned log-likelihood minimization returning a $\chi 2/Ndf$ of 1.25, showing good agreement with the nominal Monte Carlo models.

The future Deep Underground Neutrino Experiment (DUNE) relies on liquid argon as target material for the neutrino interactions in the near and far sites. The liquid argon near detector (NDLAr) has been given a modular design consisting of 35 modules (70 time-projection chambers) in a 7 by 5 array with novel pixelated charge readout systems in order to deal with the high interaction rates in the world's most intense neutrino beam. To understand the behavior of the drift fields and the pixel charge collection efficiencies inside these time-projection chambers, a series of prototypes have been studied. These studies ultimately converged into a diagnostic tool capable of identifying misbehavior in pixel trigger rates during operation.