Abstract
Using the reaction as the source of Doppler-broadened 2.14-Mev gamma radiation, resonance fluorescence from the first excited state of has been observed. For a bombarding energy of 3.0 Mev and a thick target of C, the shape of the cone containing gamma rays capable of exciting the 2.14-Mev level was determined. It agrees with the expectation based on the known excitation curve and the kinematics of the reaction assuming an isotropic distribution of the recoils. From the experimental resonance scattering cross section a mean life of 4.8× second was calculated for the first excited state of , assuming the spin of this level to be ½. A self-absorption experiment yielded second when a value of 1250° was used for the Debye temperature of C. A final value of (4.7±0.6)× second was adopted for the mean life of the 2.14-Mev first excited state of . This value of the lifetime further strengthens the argument for spin ½, but it does not allow any conclusion about the or character of the gamma-ray transition and thus about the parity of the 2.14-Mev level.
- Received 17 January 1958
DOI:https://doi.org/10.1103/PhysRev.110.906
©1958 American Physical Society