Observations on the Lifetimes of the 3.37-Mev 2⁺ State of Be¹⁰ and of the 6.14-Mev 3⁻ State of O¹⁶

NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document. An upper limit for the lifetime of the 3.37-Mev 2+ state of Be10 has been established by use of a Doppler shift technique. Be10 nuclei were produced by the Be9 (d,p)Be10 reaction and those protons leaving the Be10 in its 3.37-Mev excited state were used to select [...] rays emitted by Be10* nuclei having a well defined recoil velocity. The energy of the [...] rays emitted by these nuclei was determined by scintillation spectroscopy. The experiment was designed to look for a possible difference between the [...]-ray Doppler shifts produced when the recoil nuclei were stopped in a metal foil and when the nuclei were allowed to recoil into vacuum. A small statistically insignificant difference in shift was observed which allowed only an upper limit of about 2.0 x 10(-13) seconds for the half-life [mean life: [...] seconds] to be inferred. This limit to the mean life is compared with theoretical estimates of the lifetime based on different nuclear models. The lifetime of the 6.14-Mev 3- state of O16 has been measured by means of a recoil technique. The spatial distribution of decays of recoiling O16 nuclei, produced by the F19[...]O16+ reaction, was studied with a highly collimated [...]-ray detector. Comparison with the corresponding results obtained when the [...] nuclei were stopped at the target surface by an evaporated metallic layer provided a convenient means of determining the lifetime. A value for this half-life of (8.6 +/- 4.0) x 10(-12) seconds [mean life: [...] = (1.2 +/- 0.6) x 10(-12) seconds] has been found, consistent with previously established limits. The measured value of the mean life is compared with the theoretical values of the lifetime according to various nuclear models