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The neutrinos emitted from supernovae contain information about the physics of stellar collapse and of the nature of the neutrinos themselves. Several large detectors exist that will be capable of observing some subset of those neutrinos. In addition, we have designed OMNIS, the Observatory for Multiflavour NeutrInos from Supernovae. OMNIS will detect the neutrinos from (a) neutral-current interactions from ν e , ν µ ,ν µ , ν τ andν τ , and (b) charged-current interactions from high-momentum ν e , with lead nuclei. It will utilize two types of detectors: (1) lead slabs alternating with vertical planes of neutron detectors, in which neutrons produced by neutrino-lead interactions will be detected, and (2) lead perchlorate, in which both the resulting neutrons and Cerenkov light will be detected. OMNIS will measure neutrino masses below 100 eV, provide new information on MSW or vacuum oscillations from ν µ /ν τ to ν e , especially to 13 , and possibly diagnose the process of collapse to a black hole. It will observe the late-time evolution of the neutrino distributions, and possibly see predicted late-time effects, e.g. a phase transition from neutron-star matter to kaon-condensed matter or quark matter. OMNIS is also sensitive to some modes of nucleon decay that should make it possible to improve significantly on present limits for those modes. Of crucial importance to OMNIS is an experiment, using neutrinos from a stopped pion beam, to determine the flavour and energy-dependent response of lead to neutrinos. This will provide important input into cross section calculations for which few data currently exist. We plan to perform this experiment using one of the lead perchlorate detector modules from OMNIS.

We present systematic case studies to investigate the sensitivity of axion searches by liquid xenon detectors, using the axio-electric effect (analogue of the photoelectric effect) on xenon atoms. Liquid xenon is widely considered to be one of the best target media for detection of WIMPs (Weakly Interacting Massive Particles which may form the galactic dark matter) using nuclear recoils. Since these detectors also provide an extremely low radioactivity environment for electron recoils, very weaklyinteracting low-mass particles (< 100 keV/c 2 ), such as the hypothetical axion, could be detected as well − in this case using the axio-electric effect. Future ton-scale liquid Xe detectors will be limited in sensitivity only by irreducible neutrino background (pp-chain solar neutrino and the double beta decay of 136 Xe) in the mass range between 1 and 100 keV/c 2 . Assuming one ton-year of exposure, galactic axions (as non-relativistic dark matter) could be detected if the axio-electric coupling g Ae is greater than 10 −14 at 1 keV/c 2 axion mass (or 10 −13 at 100 keV/c 2 ). Below a few keV/c 2 , and independent of the mass, a solar axion search would be sensitive to a coupling g Ae ∼ 10 −12 . This limit will set a stringent upper bound on axion mass for the DFSZ and KSVZ models for the mass ranges m A < 0.1 eV/c 2 and < 10 eV/c 2 , respectively. Vector-boson dark matter could also be detected for a coupling constant α /α > 10 −33 (for mass 1 keV/c 2 ) or > 10 −27 (for mass 100 keV/c 2 ).