First inverse kinematics measurement of key resonances in the 22Ne(p,γ)23Na reaction at stellar temperatures
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abstract
In this Letter we report on the first inverse kinematics measurement of key
resonances in the ${}^{22}\text{Ne}(p,\gamma)^{23}\text{Na}$ reaction which
forms part of the NeNa cycle, and is relevant for ${}^{23}$Na synthesis in
asymptotic giant branch (AGB) stars. An anti-correlation in O and Na abundances
is seen across all well-studied globular clusters (GC), however, reaction-rate
uncertainties limit the precision as to which stellar evolution models can
reproduce the observed isotopic abundance patterns. Given the importance of GC
observations in testing stellar evolution models and their dependence on NeNa
reaction rates, it is critical that the nuclear physics uncertainties on the
origin of ${}^{23}$Na be addressed. We present results of direct strengths
measurements of four key resonances in
${}^{22}\text{Ne}(p,\gamma)^{23}\text{Na}$ at E$_{{\text c.m.}}$ = 149 keV, 181
keV, 248 keV and 458 keV. The strength of the important E$_{{\text c.m.}}$ =
458 keV reference resonance has been determined independently of other
resonance strengths for the first time with an associated strength of
$\omega\gamma$ = 0.439(22) eV and with higher precision than previously
reported. Our result deviates from the two most recently published results
obtained from normal kinematics measurements performed by the LENA and LUNA
collaborations but is in agreement with earlier measurements. The impact of our
rate on the Na-pocket formation in AGB stars and its relation to the O-Na
anti-correlation was assessed via network calculations. Further, the effect on
isotopic abundances in CO and ONe novae ejecta with respect to pre-solar grains
was investigated.
