Grant: Subatomic Physics Envelope - Project

This proposal supports the highly successful Canadian involvement in the T2K long baseline experiment, where an intense muon (anti)neutrino beam is produced at the J-PARC accelerator laboratory and directed 295 km away to the Super-Kamiokande detector to study their transition to other neutrino flavours arising from neutrino oscillations. Canadian members were founding members of the effort, introducing fundamental elements to the design of the experiment, and contributing key components such as the optical transition radiation detector, the fine-grained detectors and time projection chambers that form the core of the tracking system for the near detectors. With support from TRIUMF and ComputeCanada, Canadians provide other critical contributions such as the network, slow control, and databases for the near detector effort, large scale computing and data access, a new reconstruction framework for Super-Kamiokande, and beam line repair and maintenance. T2K has established strong track record of scientific achievements in the study of neutrinos including the discovery of the muon neutrino to electron neutrino appearance, the most precise measurements of the neutrino mixing angle theta23, and now the most sensitive probes of asymmetries in the neutrino vs. antineutrino oscillations which may provide clues on why the universe is matter-dominated. These scientific issues are among the most urgent facing particle physics today. Several important developments have recently converged to define the future of the T2K program. First, continuous improvements in the accelerator performance have resulted in the beam power nearly doubling to 420 kW over the past few years. With the approval of a major upgrade to the accelerator to occur in 2018, beam power is projected to double again. With further improvements, beam power of 1 MW and beyond is now projected. This has led to the proposal for ""T2K-II"", an extension of the T2K program to approximately three times the currently approved exposure in advance of next generation experiments that are scheduled to start ~2025. The additional data and statistical precision require commensurate improvements in the systematic uncertainties, leading Canadian collaborators to propose the construction of NuPRISM, a novel near detector to address the most important systematic uncertainties. The beam and near detector upgrades necessary for T2K-II were given highest priority in the 2016 KEK Project Implementation Plan, leading to Stage 1 status for T2K-II and NuPRISM in summer 2016. For FY2017-19, we propose to continue our commitments to essential parts of the experiment while starting construction of NuPRISM, for which a major request has been submitted to CFI.