Lifetime of the 6793-keV State in 15O -: art. no. 152501

The energy derived from the CN cycle at low stellar temperatures is regulated by the N-14(p,gamma)O-15 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-c.m. = -504 keV would correspond to the known E-x = 6793-keV state in O-15. We have measured a mean lifetime of 1.60(-0.72)(+0.75) fs (90% C.L.) 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.