Properties of Excited States inC14

Abstract

The 6.59-, 6.72-, 6.89-, and 7.34-MeV levels of ${\mathrm{C}}^{14}$, formed in the ${\mathrm{C}}^{13}(d, p){\mathrm{C}}^{14}$ reaction, have been studied by means of proton-gamma and gamma-gamma coincidence techniques, magnetic-pair spectrometer measurements, and observations with a Ge(Li) gamma-ray detector. Transition branches from the 6.59-MeV level are 6.59 → 6.09 [(99.0±0.4)%] and 6.59 → 0[(1.0±0.4)%]. Gamma-ray branches determined for the 6.72-MeV level are 6.72 → 6.09 [(7±2)%] and 6.72 → 0[(93±2)%]. For the 7.34-MeV level the gamma-ray branches are 7.34 → 6.72 [(35±7)%], 7.34 → 6.09 [(47±4)%], and 7.34 → 0[(18±4)%]. Multipolarity measurements with the magnetic pair spectrometer have shown that the 6.72-MeV transition is almost certainly $E3\mathrm{}$ and that the 7.34-MeV transition is not $E1\mathrm{}$. Gamma rays observed with the Ge(Li) detector from the 6.72 → 0 and 6.59 → 6.09 transitions are neither Doppler-broadened nor Doppler-shifted, whereas the gamma rays from the 7.34 → 0, 7.34 → 6.09, and 6.89 → 6.09 transitions exhibit Doppler effects. Accurate gamma-ray energies were measured for some of the cascade transitions. By combining the various observations with previous work, it is concluded that the 6.72-MeV level is $J^{\pi }=3^{-}$ and the 7.34-MeV level is $J^{\pi }=2^{-}$. Theoretical calculations have been made for the various transition rates in ${\mathrm{C}}^{14}$ and are compared with the experimental results. An incidental experimental result is a value of 495.33±0.10 keV for the energy of the first excited state of ${\mathrm{F}}^{17}$.