Chapter 4 DISCUSSION 4.1 ” FISSION PRODUCT ANALYSES —t irre, en Fission-product data for the events indicate that the close-in debris was not seriously fractionated. In some cases, the long-range results differed considerably from the close-in results; however, no clear-cut pattern of variability of isotopic ratios with distance from origin site is displayed by the data. 4-2 RARE EARTH ANALYSES With the exception of Shot 3, which cannot be considered 4 represent~ ative thermonuclear event, the rare-earth ratios were relatively constant, even though the yield of the events ranged from 2 to 14 megatons. It appears, then, that the rare-earth ratios can be used only in a qualitative manner to indicate a thermonuclear event. For example, if the heavy~ element, data shows that plutonium fissioning notsignificant consideration, ro , ' ——— a ge -——_ re - J a eo es ee [However,LRD Eu!58/sm!53, Tb '!¥%Sm'53, and Tbiéi/Eu 156 ratios for Shot 1 are consistent with the close-in results within the limits of reliability of the data. It was not possible to determine Ga? on LRD samples because of its low fission yield and short half-life. 37