s . in s - de t ] 3 0 Ju n 19 99 Physics of Particle Detection 1

In this review the basic interaction mechanisms of charged and neutral particles are presented. The ionization energy loss of charged particles is fundamental to most particle detectors and is therefore described in more detail. The production of electromagnetic radiation in various spectral ranges leads to the detection of charged particles in scintillation, Cherenkov and transition radiation counters. Photons are measured via the photoelectric effect, Compton scattering or pair production, and neutrons through their nuclear interactions. A combination of the various detector methods helps to identify elementary particles and nuclei. At high energies absorption techniques in calorimeters provide additional particle identification and an accurate energy measurement. INTRODUCTION The detection and identification of elementary particles and nuclei is of particular importance in high energy, cosmic ray and nuclear physics [1–6]. Identification means that the mass of the particle and its charge is determined. In elementary particle physics most particles have unit charge. But in the study e.g. of the chemical composition of primary cosmic rays different charges must be distinguished. Every effect of particles or radiation can be used as a working principle for a particle detector. The deflection of a charged particle in a magnetic field determines its momentum p; the radius of curvature ρ is given by ρ ∝ p z = γm0βc z (1) where z is the particle’s charge, m0 its rest mass and β = v c its velocity. The particle velocity can be determined e.g. by a time-of-flight method yielding β ∝ 1 τ , (2) 1) ICFA Instrumentation School, Istanbul, Turkey, June 28 July 10, 1999