Lifetime of the 6793-keV State in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mmultiscripts><mml:mrow><mml:mi>O</mml:mi></mml:mrow><mml:mprescripts/><mml:mrow/><mml:mrow><mml:mn>15</mml:mn></mml:mrow><mml:mrow/><mml:mrow/></mml:mmultiscripts></mml:mrow></mml:math>

The energy derived from the CN cycle at low stellar temperatures is regulated by the ${}^{14}\mathrm{N}(p,\ensuremath{\gamma}{)}^{15}\mathrm{O}$ 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 ${E}_{\mathrm{c}.\mathrm{m}.}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}\ensuremath{-}504\mathrm{keV}$ would correspond to the known ${E}_{x}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}6793\ensuremath{-}\mathrm{keV}$ state in ${}^{15}\mathrm{O}$. We have measured a mean lifetime of ${1.60}_{\ensuremath{-}0.72}^{+0.75}\mathrm{fs}$ $(90%\mathrm{C}.\mathrm{L}.)$ for this state using the Doppler-shift attenuation method. This lifetime is a factor of 15 longer than that inferred from the $(p,\ensuremath{\gamma})$ data and implies that the contribution of the subthreshold resonance is negligible.

Hali tarjima qilinmagan