Academics: Dr Steve Boyd, Dr Ben Richards
Postdoctoral Fellows : Dr David Hadley
Students: Mr Nicholas Latham
Hyper-K is a successor project to Super-K with the capability of making definitive measurements of the main outstanding questions in oscillation physics: CP-violation, mass hierarchy and the θ 23 octant. The detector will also have a world leading sensitivity to nucleon decay and the observation of cosmic origin neutrinos. The experiment will operate in the same beamline as T2K with the same off-axis configuration. The Hyper-K detector baseline design (pictured below) will be a third generation water Cherenkov detector in Kamioka with a 1.0 (0.56) Mt total (fiducial) mass - making it 20 (25) times larger than Super-K. Hyper-K construction will begin in 2022 and first data is expected in 2025-2026.
Based on an exposure of 7.5 MW x 107 sec, and assuming the mass hierarchy is known and sin2 2θ13=0.1, the expected CP-violation coverage is illustrated in the plot below: a 3σ (5 σ) measurement can be made for 76% (58%) of all CP-phase values.
Neutrino Flavour Oscillations and CP violation
Hyper-K's goals are to determine the mass hierarchy (which of the three known mass states is the heaviest?), to measure CP violation in the lepton sector; a measurement which may hold a possible explanation for the matter-antimatter asymmetry of our universe—and to make high-precision measurements of the oscillation parameters that T2K and previous the generation of neutrino flavour oscillation experiments have pioneered.
Solar Neutrino Physics
The sun is a prolific generator of neutrinos. Super-K and previous solar neutrino experiments have already shown the existence of effects of earth matter on the oscillation of neutrinos as they travel through the earth. Hyper-K will measure these effects ever more precisely. This will lead us to a better understanding of the earth's interior and the solar atmosphere.
Computer simulations of core collapse supernovae is a complicated process and is known not to reproduce the characteristics of supernovae that have been observed on Earth. The number, flavour, energy and arrival time of neutrinos from a core-collapse Galactic supernova are probes of the physics of the supernova explosion process. Observation of these neutrinos in Hyper-K, and other neutrino detectors around the planet will afford us a unique probe of the supernova environment. However, Galactic supernovae do not happen regularly - the last was in 1987. Hyper-K would observe more than 60,000 supernova neutrinos in a time window 10 seconds wide should one explore within a radius of 30,000 light years.
It is well-known that the Standard Model of Particle Physics is only part of a new, larger, and yet still undeveloped theory. Grand Unified Theories tend to predict that protons can decay in lighter yet currently unobserved particles. Hyper-K will provide the largest source of possible decaying protons, and is expected to be able to increase the current minimum proton decay time by an order of magnitude.