Low-Energy Measurement of the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mmultiscripts><mml:mrow><mml:mi>B</mml:mi></mml:mrow><mml:mprescripts/><mml:mrow/><mml:mrow><mml:mn>7</mml:mn></mml:mrow><mml:mrow/><mml:mrow/></mml:mmultiscripts></mml:mrow><mml:mi>e</mml:mi><mml:mo>(</mml:mo><mml:mi mathvariant="italic">p</mml:mi><mml:mo>,</mml:mo><mml:mi mathvariant="italic">γ</mml:mi><mml:mo>)</mml:mo><mml:mrow><mml:mmultiscripts><mml:mrow><mml:mi>B</mml:mi></mml:mrow><mml:mprescripts/><mml:mrow/><mml:mrow><mml:mn>8</mml:mn></mml:mrow><mml:mrow/><mml:mrow/></mml:mmultiscripts></mml:mrow></mml:math>Cross Section

We have measured the cross section of the ${}^{7}\mathrm{Be}(p,\ensuremath{\gamma}{)}^{8}\mathrm{B}$ reaction for ${E}_{\mathrm{c}.\mathrm{m}.}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}185.8$, 134.7, and 111.7 keV using a radioactive ${}^{7}\mathrm{Be}$ target (132 mCi). Single and coincidence spectra of ${\ensuremath{\beta}}^{+}$ and $\ensuremath{\alpha}$ particles from ${}^{8}\mathrm{B}$ and ${}^{8}{\mathrm{Be}}^{*}$ decay, respectively, were measured using a large acceptance spectrometer. The zero energy $S$ factor inferred from these data is $18.5\ifmmode\pm\else\textpm\fi{}2.4\mathrm{eV}\mathrm{b}$ and a weighted mean value of $18.8\ifmmode\pm\else\textpm\fi{}1.7\mathrm{eV}\mathrm{b}$ (theoretical uncertainty included) is deduced when combining this value with our previous results at higher energies.

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