Abstract
The 7.656-Mev nuclear pair transition from the 0+ second excited state of has been observed in the reaction by means of an intermediate-image pair spectrometer. With a beam of 5.81-Mev alpha particles incident on a 0.7-Mev thick Be foil target the observed intensity ratio of the 7.656-Mev pair line to the 4.433-Mev pair line from the 2+ first excited state of was (5±1.5)×. Approximately the same intensity ratio was found with both 5.38- and 5.81-Mev alpha particles incident on thick (6 mg/) Be targets. By applying the appropriate factors for the spectrometer efficiency and for the internal pair conversion coefficient of the 4.433-Mev transition the derived ratio of pair to total widths of the 7.656-Mev level is where , the ratio of neutron populations in the reaction. As a rough estimate is assumed to be ∼8 based on the only information available. This leads to which is a factor of ∼15 smaller than estimates by Cook et al. in which the width for the alpha-particle decay of the level was taken as of the Wigner limit. The most plausible explanation of the data is that is close to the Wigner limit.
- Received 29 October 1959
DOI:https://doi.org/10.1103/PhysRev.118.235
©1960 American Physical Society