Direct measurement of the low-energy resonances in 22Ne(a, ?) 26Mg reaction

The Ne-22(alpha, gamma) Mg-26 is an important reaction in stellar helium burning environments as it competes directly with one of the main neutron sources for the s-process, the Ne-22(alpha, n) Mg-25 reaction. The reaction rate of the 22Ne(alpha, gamma) 26Mg is dominated by the low-energy resonances at E ( lab)(alpha)= 650 and 830 keV, respectively. The E-alpha(lab) = 830-keV resonance has been measured previously, but there are some uncertainties in the previous measurements. We confirmed the measurement of the E-alpha(lab) = 830-keV resonance using implanted Ne-22 targets. We obtained a resonance strength of w gamma = 35 +/- 4 mu eV and provide a weighted average of the present and previous measurements of w gamma = 35 +/-; 2 mu eV with reduced uncertainties compared to previous studies. We also attempted to measure the strength of the predicted resonance at E-alpha(lab) = 650 keV directly for the first time and found an upper limit of w gamma < 0.15 mu eV for the strength of this resonance. In addition, we also studied the E (lab )(P)= 851-keV resonance in Ne-22(p, gamma) Na-23 and obtained a resonance strength of w gamma = 9.2 +/- 0.7 eV with significantly lower uncertainties compared to previous measurements.