Search for neutrino bursts from gravitational stellar collapses

Theoretical models of stellar evolution predict that massive stars should end their lives with core implosion, eventually followed by envelope explosion. The gravitational collapse is brought about by many effects among which the most important ones are thermonuclear burning in the shells surrounding the core (which makes the core mass M/sub c/ to exceed the Chandrasekar limit mass and neutronization of matter (which reduces both the electron pressure and the lepton fraction y/sub e/ in the core). The main features of neutrino emission which are important for burst detection at the earth in an underground laboratory are summarized