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34 A
detect light flashes too feeble for visual detection and produce large pulses of very short duration. These early results by Curran and Baker and independently by Kallmann opened up the whole field of modern scintillation counting. It was soon found that successful scintillation counting was by no means limited to the old stand-bys such as zinc sulfideor calcium tungstate, but t h a t many organic solids, liquids, and solutions afforded interesting possibilities. Some years ago, we mentioned in this column that nuclear physicists would do well to enlist the aid of good organic chemists in this search. This must have occurred to hundreds of others, because, at present, the subject is in a high state of development and lias enlisted the efforts of organic chemists, students of solid state physics, and, of course, the full resources of modern electronics. Not only has the choice of substance been reinvestigated, but it has been produced in clear, single crystals. A good scintillator produces large pulses of short duration, is trans parent to its own light pulses, and emits in a spectral region to which the photomultiplier is most sensitive. The entire subject is now so well advanced t h a t special monographs have appeared and have filled the need of classifying and ordering our present knowledge. J. B. Berks ("Scin tillation Counters," 148 + viii pages, New York, McGraw-Hill Book Co., Lon don, Pergamon Press, Ltd., 1953), in eight concise chapters discusses the principles of the scintillation counter and the latest de velopments in photomultiplier tubes, many of which are concerned directly with this problem. Other questions dealt with are pulse height and time resolution. Separate chapters cover inorganic phos phors, organic crystalline phosphors, and organic plastic and solution phosphors. A final chapter deals with applications, many of which are distinctive, such as the spec trometry of gamma and x-radiations. In the measurement of decay times, or of in tervals between ionizing events, the scin tillation counter offers an improvement of more than 1000-fold in resolving times of gas counters and will discriminate to the order of 10 ~9 second. Another timely and informative mono graph is by S. C. Curran of the University of Glasgow ("Luminescence and the Scin tillation Counter," 219 + χ pages, London, Butterworths Scientific Publications, New York, Academic Press, 1953). Of the twelve chapters, the first three are concerned with the general principles of the scintillation counter, radiations, and ANALYTICAL
CHEMISTRY
