[9]Not all nuclear reactors are appropriate for this work. For example, reactors designed for electric power production do not have the means built into them for inserting and removing small samples for a “short” period of irradiation. [10]A scintillation detector is a crystalline device, usually sodium iodide containing a small amount of thallium, which has the property of emitting light when energy is absorbed from nuclear radiation. [11]After a 10-minute irradiation and a 3-minute delay before counting, corrected for decay to a common time. [12]One mole is the atomic weight of an atom or molecule expressed in grams, or the weight of 6.02 × 10²³ atoms or molecules per mole. [13]ln 2 is the natural logarithm of 2. READING LIST General Information About Nuclear Science _Secrets of the Nucleus_, Joseph S. Levinger, McGraw-Hill Book Company, New York, 1967, 127 pp., $0.50. _Working With Atoms_, Otto R. Frisch, Basic Books, Inc., Publishers, New York, 1965, 96 pp., $3.50. _The Atom and Its Nucleus_, George Gamow, Prentice-Hall, Inc., Englewood Cliffs, New Jersey, 1961, 153 pp., $1.95. _Inside the Nucleus_, Irving Adler, The John Day Company, Inc., New York, 1963, 192 pp., $4.95. _Radioisotopes and Radiation_, John H. Lawrence, Bernard Manowitz, and Benjamin S. Loeb, Dover Publications, Inc., New York, 1964, 131 pp., $2.50. _Sourcebook on Atomic Energy_ (third edition), Samuel Glasstone, Van Nostrand Reinhold Company, New York, 1967, 883 pp., $15.00. The Semiconductor Revolution in Nuclear Radiation Counting, J. M. Hollander and I. Perlman, _Science_, 154: 84 (October 7, 1966). About Activation Analysis Popular Level Neutron Activation Analysis, Vincent P. Guinn, _International Science and Technology, Prototype Issue,_ 74 (1961). Distribution of Arsenic in Napoleon’s Hair, Hamilton Smith, Sten Forshufvud, and Anders Wassen, _Nature_, 194: 725 (May 26, 1962). Nuclear Activation Analysis, Richard E. Wainerdi and Norman P. DuBeau, _Science_, 139: 1027 (March 15, 1963). Neutron Activation Analysis, W. H. Wahl and H. H. Kramer, _Scientific American_, 68: 210 (April 1967). Technical Level _Activation Analysis Handbook_, Robert C. Koch, Academic Press, Inc., New York, 1960, 219 pp., $8.00. Neutron Activation Experiments in Radiochemistry, K. S. Vorres, _Journal of Chemical Education_, 37: 391 (August 1960). Radioactivation Analysis, H. J. M. Bowen and E. Gibbons, Oxford University Press, London, England, 1963, 295 pp., $8.00. _Neutron Irradiation and Activation Analysis_, Denis Taylor, Van Nostrand Reinhold Company, New York, 1964, 185 pp., $8.95. _Guide to Activation Analysis_, William A. Lyon (Ed.), Van Nostrand Reinhold Company, New York, 1964, 186 pp., $5.95.