ABSTRACT
This chapter discusses the direct methods of measuring the cosmic ray spectrum and composition is available. Placing detectors on the space shuttle allows for somewhat larger areas and much longer exposure times. Small detectors have also been placed on satellites. The charge detector is composed of 200–400 micron thick emulsions as well as some plastic detectors. The specific ionization is measured using the time-tested emulsion techniques of grain density, grain gap distribution counting, and delta ray distributions. The plastic detectors respond to the passage of heavily ionizing radiation by exhibiting a track of intensely damaged material along the particle trajectory. The calorimeter is seven radiation lengths deep and is composed of thin lead sheets, alternating with thin emulsion plates and X-ray film that is sensitive to high energy γ-rays. Analysis of the X-ray film density allows a measurement of individual γ-ray energies.
