ABSTRACT
Neutrinos mostly originate from the decay of secondaries like pions resulting from “beam dump” interactions of protons with other protons or photons as in accelerator experiments. Like photons, neutrinos are not affected by the presence of a magnetic field and thus could point to sources. The search for high-energy neutrinos can be split into two categories. One is the obvious search for point sources, in the hope that a signal will shed light on the question of what the sources of cosmic rays are. The second one is a diffuse neutrino flux like the one observed in gamma rays. Active galactic nuclei are the brightest sources in the universe. It is anticipated that the beams accelerated near a central black hole are dumped on the ambient matter in the active galaxy. Gamma Ray Bursters may have become the best motivated source for high-energy neutrinos.
