Cover courtesy Los Alamos Scientific Laboratory (LASL) Figure 1 A, Argonne National Laboratory (ANL); B and C; LASL; D, Cornell University. Figure 2 LASL Figure 3 Brookhaven National Laboratory (BNL) Figure 5 LASL Figure 6 LASL Figure 7 BNL Figure 8 LASL Figure 9 LASL Figure 10 Dr. Charles E. Miller, ANL Figure 12 LASL Figure 13 National Reactor Testing Station Figure 18 BNL Figure 19 National Naval Medical Center Figure 20 LASL Figure 21 Colorado State University Figure 23 Cornell University Figure 24 Pacific Northwest Laboratory Center-spread Professor J. K. Miettinen, University of Helsinki This booklet is one of the “Understanding the Atom” Series. Comments are invited on this booklet and others in the series; please send them to the Division of Technical Information, U. S. Atomic Energy Commission, Washington, D. C. 20545. Published as part of the AEC’s educational assistance program, the series includes these titles: NUCLEAR POWER AND MERCHANT SHIPPING PLUTONIUM OUR ATOMIC WORLD NUCLEAR ENERGY FOR DESALTING CONTROLLED NUCLEAR FUSION WHOLE BODY COUNTERS PLOWSHARE POPULAR BOOKS ON NUCLEAR SCIENCE SNAP, NUCLEAR SPACE REACTORS NUCLEAR REACTORS ATOMS, NATURE, AND MAN MICROSTRUCTURE OF MATTER SYNTHETIC TRANSURANIUM ELEMENTS COMPUTERS RESEARCH REACTORS GENETIC EFFECTS OF RADIATION POWER FROM RADIOISOTOPES NONDESTRUCTIVE TESTING RARE EARTHS FOOD PRESERVATION BY IRRADIATION FALLOUT FROM NUCLEAR TESTS RADIOACTIVE WASTES RADIOISOTOPES IN INDUSTRY ATOMS AT THE SCIENCE FAIR RADIOISOTOPES AND LIFE PROCESSES ATOMIC FUEL ATOMIC POWER SAFETY DIRECT CONVERSION OF ENERGY CAREERS IN ATOMIC ENERGY RADIOISOTOPES IN MEDICINE ACCELERATORS NUCLEAR TERMS, A BRIEF GLOSSARY NEUTRON ACTIVATION ANALYSIS ATOMS IN AGRICULTURE NUCLEAR CLOCKS POWER REACTORS IN SMALL PACKAGES NUCLEAR POWER PLANTS YOUR BODY AND RADIATION A single copy of any one booklet, or of no more than three different booklets, may be obtained free by writing to: USAEC, P. O. BOX 62, OAK RIDGE, TENNESSEE 37830 Complete sets of the series are available to school and public librarians, and to teachers who can make them available for reference or for use by groups. Requests should be made on school or library letterheads and indicate the proposed use. Students and teachers who need other material on specific aspects of nuclear science, or references to other reading material, may also write to the Oak Ridge address. Requests should state the topic of interest exactly, and the use intended. In all requests, include “Zip Code” in return address. Printed in the United States of America USAEC Division of Technical Information Extension, Oak Ridge, Tennessee February 1967