We explore approximations to the effective S factor for the ${}^7\mathrm{Be}(p,\gamma {)}^8\mathrm{B}$ reaction using different approximations for the integral over the Gamow peak. In the temperature range of interest for solar neutrino production, $S_{\mathrm{eff}}$ may be determined to within 0.5% from $S\left(20\right)\mathrm{}$ with no direct information on the derivatives of $S\left(E\right).$

• Received 6 July 1998

DOI:https://doi.org/10.1103/PhysRevC.58.3002