The Role of Particle Channelling in Detector Systems

The orientation dependence of the energy loss rates of energetic protons and alpha particles in thin silicon crystals was first reported at the last Semiconductor and Scintillation Counter Symposium two years ago. Since that time the effect has been extensively and systematically studied in several laboratories. Particle channeling, as the effect is now called, can be manifest as anomalous energy loss rate, anomalous range, anomalous charge production, anomalous radiation damage, anomalous scattering or anomalous reaction yield. These phenomena can affect appreciably the results obtained from the use of crystalline detectors for charged particles and can also affect general nuclear and atomic scattering measurements independent of the type of detector used. It is important therefore that the nuclear experimentalist be aware of the nature and causes of particle channeling and be familiar with the techniques to test for, eliminate or in some cases use the effect in his measurements.