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

TL;DR

This study presents a refined lifetime measurement of the 6792 keV state in 15O using an improved Doppler-shift attenuation method, crucial for astrophysical S factor calculations, but finds no evidence of a finite lifetime as previously suggested.

Contribution

The paper introduces an enhanced experimental technique for measuring lifetimes of excited states in 15O, providing more accurate data relevant for astrophysical models.

Findings

No confirmed finite lifetime for the 6792 keV state.

Measured lifetime upper limit tau<0.77 fs for the 6792 keV state.

Consistent lifetime measurement for the 5181 keV state with literature.

Abstract

We report on a new lifetime measurement of the E_x=6792 keV state in 15O via the Doppler-shift attenuation method at the E=259 keV resonance in the reaction 14N(p,g)15O. This subthreshold state is of particular importance for the determination of the ground state astrophysical S factor of 14N(p,g)15O at stellar energies. The measurement technique has been significantly improved compared with previous work. The conclusion of a finite lifetime drawn there cannot be confirmed with the present data. In addition, the lifetime of the two states at E_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_x =6172 and 6792 keV states, respectively, corresponding to tau<0.77 fs. The attenuation factor for the E_x=5181 keV state results in F(tau)=0.78+/-0.02 corresponding to tau=8.4+/-1.0 fs in excellent agreement with literature.