ar X iv : h ep - p h / 93 08 37 3 v 1 3 1 A ug 1 99 3 University of Wisconsin - Madison MAD / PH / 785 August 1993 Astroparticle Physics with High Energy

The first optical modules of the Baikal high energy neutrino telescope have recently been deployed. Commissioning of the AMANDA, DUMAND and NESTOR detectors will follow soon. Before discussing the detectors we review the arguments that pinpoint 0.1 km as the natural scale of a neutrino telescope. Though present detectors do not quite reach this goal, their techniques, if successful, can be exploited to build km detectors for a cost not exceeding one hundred million dollars. Motivations for the construction of km deep underground detectors include i) neutrino astronomy and the search for cosmic accelerators: we will focus our discussion on recent claims that active galactic nuclei are the accelerators of the highest energy cosmic rays. If this is true they are inevitably high-flux sources of very energetic neutrinos; ii) neutrino oscillations using the atmospheric neutrino beam: we emphasizing the unique capability of surface neutrino telescopes, i.e. detectors positioned at a depth of roughly 1 km, to detect neutrinos and muons of similar energy. In a νμ oscillation experiment one can therefore tag the π progenitor of the neutrino by detecting the muon produced in the same decay. This eliminates the model dependence of the measurement inevitably associated with the calculation of the primary cosmic ray flux. We will show that planned surface neutrino telescopes probe the parameter space ∆m >∼ 10 eV and sin 2θ >∼ 10 using this technique. Recently underground experiments have given hints for neutrino oscillations in this mass range. iii) the search for neutrinos from the annihilation of dark matter particles