Lifetime measurement of the 6792 keV state in {sup 15}O, important for the astrophysical S factor extrapolation in {sup 14}N(p,{gamma}){sup 15}O

We report on a new lifetime measurement of the E{sub x}=6792 keV state in {sup 15}O via the Doppler-shift attenuation method at the E=259 keV resonance in the reaction {sup 14}N(p,{gamma}){sup 15}O. This subthreshold state is of particular importance for the determination of the ground state astrophysical S factor of {sup 14}N(p,{gamma}){sup 15}O at stellar energies. The measurement technique has been significantly improved over that used in previous work. The conclusion of a finite lifetime drawn there cannot be confirmed with the present data. In addition, the lifetimes of the two states at E{sub x}=5181 and 6172 keV have been measured with the same technique in order to verify the experimental method. We observe an attenuation factor F({tau})>0.98 for the E{sub x}=6172 and 6792 keV states, respectively, corresponding to {tau}<0.77 fs. The attenuation factor for the E{sub x}=5181 keV state results in F({tau})=0.78{+-}0.02 corresponding to {tau}=8.4{+-}1.0 fs, which is in excellent agreement with literature.