Search for nonresonant capture in theO16(α,γ)20Ne reaction at low energies

${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$ recoils produced from the ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$(α,γ${)\mathrm{}}^{20}$Ne reaction were detected in coincidence with capture γ rays using a recoil separator, NaI(Tl) γ-ray detectors, and a helium gas target. Total cross sections for cascade and ground state capture were measured in the range $E_{\mathrm{c}.\mathrm{m}.\mathrm{}=1.7\mathrm{}–}$2.35 MeV. Improved measurements of the total width and resonance strength of the $E_{\mathrm{c}.\mathrm{m}.\mathrm{}=1.99\mathrm{}}$ MeV ($J^{\pi }$ ${=0\mathrm{}}^{+}$) resonance and the resonance strength of the $E_{\mathrm{c}.\mathrm{m}.\mathrm{}=1.054\mathrm{}}$ MeV ($J^{\pi }$ ${=1\mathrm{}}^{\mathrm{-}}$) resonance are reported. The astrophysical S factor for nonresonant capture into the ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$ ground state was measured to be 0.26±0.07 MeV b, assuming an energy-independent S factor between $E_{\mathrm{c}.\mathrm{m}.\mathrm{}=1.7\mathrm{}}$ and 2.35 MeV. Using theoretical estimates for the energy dependence and branching ratios for the nonresonant capture, a best estimate for the total S factor at 300 keV of 0.7±0.3 MeV b is determined.