Lifetime of the 6793-keV State inO15

The energy derived from the CN cycle at low stellar temperatures is regulated by the ${}^{14}\mathrm{N}(p,\gamma {)}^{15}\mathrm{O}$ reaction. A previous direct measurement of this reaction has been interpreted as showing evidence for a subthreshold resonance which makes a major contribution to the reaction rate at low temperatures. This resonance, at $E_{\mathrm{c}.\mathrm{m}.\mathrm{}}=-504\mathrm{}\mathrm{keV}$ would correspond to the known $E_x=6793\mathrm{}-\mathrm{keV}$ state in ${}^{15}\mathrm{O}$. We have measured a mean lifetime of ${1.60}_{-0.72\mathrm{}}^{+0.75\mathrm{}}\mathrm{fs}$ $(90\%\mathrm{C}.\mathrm{L}.\mathrm{})$ for this state using the Doppler-shift attenuation method. This lifetime is a factor of 15 longer than that inferred from the $(p,\gamma )$ data and implies that the contribution of the subthreshold resonance is negligible.