Each of seven Australasian tektites contains about 1 x l0(8) atoms of beryllium-10 (half-life, 1.53 x 10(6) years) per gram. Cosmic-ray bombardment of the australites cannot have produced the measured amounts of beryllium-10 either at the earth's surface or in space. The beryllium-10 contents of these australites are consistent with a sedimentary precursor that adsorbed from precipitation beryllium-10 produced in the atmosphere. The sediments must have spent several thousand years at the earth's surface within a few million years of the tektite-producing event.

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A study was made of electric monopole transitions from the 0+ first excited states of certain nuclei. A search for 6.05-Mev O' EO conversion electrons gave an upper limit of 1&(10 4 for the ratio of the probability for conversion electrons to that of pair emission.Ca 0 EO conversion electrons were observed and a ratio of W"""""/W~, ;, = (6.94&0.20)X 10 ' was obtained. The momentum distributions of both components of pairs from the first excited state were observed. An upper limit of 6X10 ' was placed on the ratio of double gamma emission to pair emission. The energy of the first excited state was found to be 3.353~0.003Mev by measurement of the conversion electron energy. An excitation function for population of the first excited state of Ge'~b y inelastic scattering of protons was observed between 2.3 and 6.2-Mev proton bombarding energy. The E and (X+M +I&7+0) EO conversion electrons were resolved and the ratio Wrr/W&z+sr+&v+o& 8 70+0 06 was. obtained. The energy of the erst excited state was found to be 0.690+0.001 Mev.An excitation function for population of the first excited state of Zrgo by inelastic scattering of protons was obtained between 3.35 and 6.5 Mev proton bombarding energy. The momentum distributions of both components of pairs were observed. The energy of the first excited state was measured as 1.762~0.002Mev. 2.38&0.08 was obtained for the ratio W", """"/W~", . The X and (L+M+I&'/+0) conversion electrons were resolved and the ratio Wz/W&IyM~Nyo& 7 06+0.08 was obtained.All results are consistent within experimental errors with theoretical predictions.A study was made of the relative decay rates of the electronic decay modes in the cases of 0' y Ca ) Ge ', and Zr". Nuclei with 0+ first excited states were chosen because of the absence of competing gamma cascades and because of the relatively high (p, rs) thresholds in these magic nuclei. In addition, a search for double gamma emission was made in the case of Ca".