The connection between cosmic rays and particle physics has experienced a renewal of interest in the past decade. Large detectors, deep underground, sample groups of coincident cosmic ray muons and study atmospheric neutrinos while searching for proton decay, monopoles, neutrino oscillations, etc. Detector arrays at the surface measure atmospheric cascades in the effort to identify sources of the most energetic naturally occurring particles. This book is an introduction to the phenomenology and theoretical background of this field of particle astrophysics. The book is directed to graduate students and researchers, both experimentalists and theorists, with an interest in this growing interdisciplinary field.

The book is divided into an introductory section and three main parts. The two introductory chapters give a brief background of cosmic ray physics and particle physics. Chapters 5 through 8 concern cosmic rays in the atmosphere – hadrons, photons, muons and neutrinos. The second major part (chapters 9–13) is about propagation, acceleration and origin of cosmic rays in the galaxy. Air showers and related topics are the subject of the last four chapters.

I am grateful to many colleagues at Bartol and elsewhere for discussions which have helped me learn about aspects of the field. I thank Alan Watson, Raymond Protheroe, Paolo Lipari, Francis Halzen, David Seckel, Todor Stanev, Floyd Stecker and Carl Fichtel for reading various chapters and offering helpful suggestions.

I thank Leslie Hodson, Jack van der Velde, Jay Perrett and Sergio Petrera for providing me with photographs to illustrate the book.