The crystal conduction counter

Whenever a nuclear physicist observes a new effect caused by an atomic particle, he tries to make a counter out of it. After all, neutrons, protons, and their ilk are elusive little beasties and their detection and measurement form the life blood of experimental nuclear physics. The fact that charged particles can ionize gas molecules has been exploited to produce the ionization chamber, the proportional counter, and the Geiger counter. The fact that certain solids luminesce when bombarded with high‐speed particles made possible many of the early studies in nuclear physics where the observer peered at a zinc sulphide screen through a microscope and laboriously counted the minute light flashes caused by alpha particles striking the screen. Recently, a photomultiplier tube has supplanted the eye‐weary observer, resulting in the modern scintillation counter which plays an important role in all nuclear physics laboratories today. Thus it is only logical that attempts should be made to utilize the electrical effects produced in solids by ionizing particles—the solid state equivalent of an ionization chamber. Indeed, such effects have been sought for many years, yet it is only since World War II that new theory and new techniques have demonstrated that the crystal counter is actually a potentially useful measuring instrument. That its application is potential is an unfortunate consequence of the complexity of the solid state and the lack of an adequate understanding of the detailed electrical behavior of real crystals.