EXCITED STATES OF O18 STUDIED BY THE REACTION

Authors:
  • ALA. E. Litherland
    A. E. Litherland
  • RBR. Batchelor
    R. Batchelor
  • AFA. J. Ferguson
    A. J. Ferguson
  • HGH. E. Gove
    H. E. Gove
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Abstract
Gamma rays from the excited states of O18 at 3.63 and 3.92 Mev have been observed using the reaction [ ] at an incident O16 energy of 14 Mev. Both states were observed to emit gamma rays to the 1.98-Mev 2+ first excited state of O18. No evidence for crossover transitions was found and in each case the crossover transition was estimated to be [ ] of the cascade transition. Angular correlations of the gamma rays were obtained and these strongly support an assignment of spin 0 to the 3.63-Mev state and a spin of 2 for the 3.92-Mev state. These assignments have been confirmed by a recent experiment on the O16(H3, p)O18 reaction which gives the assignments 0+ and 2+ for these two states. Thus the states at 3.55, 3.63, and 3.92 Mev form a triplet with assignments 4+, 0+, and 2+ which strongly resembles the vibrational spectra found in heavier nuclei. However, the measured angular correlations of the gamma rays from the 3.92-Mev state show only a small admixture of electric quadrupole in the 1.94-Mev gamma ray with relative amplitude +0.1 ±.1. A lower limit of ~10−12 seconds on the lifetime of the 3.63-Mev state was obtained from the absence of a doppler shift of the 1.65-Mev cascade gamma ray.

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