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Uranium 234 and 235 were found to be highly enriched relative to uranium 238 in several rain samples collected at Fayetteville, Arkansas, during the months of April and May 1980. The anomalous uranium appears to have originated from the Soviet satellite Cosmos‐954, which fell over Canada on January 24, 1978. The uranium fallout occurred just about the time Mount St. Helens erupted on May 18, 1980. The concentration of 238U in rain increased markedly after the eruption of Mount St. Helens, and it appeared as if a large quantity of natural uranium was injected into the atmosphere by the volcanic eruption. The pattern of variation of the concentrations of uranium in rain after the eruption of Mount St. Helens was found to be similar to that of plutonium isotopes.

у RAYS FROM DECAY OF 35-DAY Nb 95 691been estimated to be about 1.5% that of the strong line. This intensity is consistent with about a 3% impurity of Zr 95 in the sample. Another well-known gamma ray 6 from the decay of Zr 95 has an energy of 760 keV and its intensity is about 80% of that of the 726-keV gamma ray. Its presence is suggested by a slight hump on the low-energy side of the line from the decay of Nb 95 . It is clear from the figures that no gamma ray of any ap preciable intensity is present in the spectrum near 753 keV. It has been estimated that such a gamma ray would have been detected if its intensity were ^ \°/ 0 of that of the strong line at 765.8 keV.The spectrometer was calibrated by observing the gamma ray 7 at 661.S95zbO.076 keV from Cs 137 (Fig. 2)