At ultra-high energy the radiation is produced by interactions of cosmic ray particles accelerated in explosive events such as supernovae or hypernovae, black holes or, possibly, the big bang. This work introduces young researchers to the field of ultra-high energy astrophysics including charged particles, gamma rays and neutrinos.

This volume comprises selected lectures presented in the Ninth Course of the International School ofCosmic-Ray Astrophysics held at the Ettore Majorana Centre in Erice, Sicily, May 7-18,1994. Director ofthe Centre is A. Zichichi, assisted by M. Zaini. Director ofthe School is M. M. Shapiro. 1. P. Wefel was co-director of the Ninth Course, which was also a NATO Advanced Study Institute (ASI), and NATO support is gratefully acknowledged. Devoted to problems and prospects in high-energy astrophysics and cosmology, the major areas explored in this course were: gamma-ray, X-ray, and neutrino...

The symbiosis between particle physics and cosmology has virtually become a conjugal relationship. Hence the 9th biennial Course of the International School of Cosmic-Ray Astrophysics was designed to bridge these formerly dispa- rate disciplines. This NATO Advanced Study Institute (ASI) took place at the Ettore Majorana Centre in Erice, Italy, June 20-30, 1992. Seventy participants from 17 countries enjoyed the opportunities for lively interactions as much as they benefitted from the stimulating lectures. This volume is based on a selection of lectures and shorter talks presented at the...