Michael Friedlander begins by quoting the introductory sentence from Cecil Powell's acceptance speech for the Nobel Prize in Physics in 1950: "Coming out of space and incident on the high atmosphere, there is a thin rain of charged particles known as primary cosmic radiation."
A Thin Cosmic Rain - Particles from Outer Space is a well-written, intriguing introduction to cosmic rays (CR) that will appeal to readers with a moderate technical background. The later chapters were especially fascinating.
Friedlander's text involves relatively little mathematics, but is packed with helpful technical graphs and charts, particle track photos, instrumentation diagrams, and astronomical photographs.
The early chapters provide a historical context that may be largely familiar to many readers: the discovery of cathode rays (electrons), x-rays, and radioactive decay; the high altitude balloon flights by Victor Hess that resulted in the discovery of cosmic rays, "an extra-terrestrial source of penetrating radiation"; the advances in particle tracking technology in the twentieth century; and the impact of satellite borne instrumentation on CR research, including the discovery of the Van Allen belts.
The middle chapters - Particles from the Sun, Cosmic Rays in the Galaxy, The Energy Spectrum, and Ultra-High Energies - are a little more technical and may require some study as they lay the foundation for the final chapters. These chapters immediately engaged my interest and I found myself reading late into the evening. I would finish one chapter and immediately begin another.
The remaining chapters, especially Nuclear Clues, The Origin of Cosmic Rays, Cosmic Electrons and Gamma Rays, and Cosmic Neutrinos, are also quite good. Professor Friedlander addressed such topics as the nucleosynthesis model, the galactic leaky box model, calculations of CR travel paths, the CR budget for our galaxy, the spectral shape of supernova emissions, and synchrotron radiation.
My hardcover copy of A Thin Cosmic Rain was published by Harvard University Press, 2000. An earlier version, Cosmic Rays, was published in 1989.
