Electromagnetic dissociation of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow/><mml:mrow><mml:mn>8</mml:mn></mml:mrow></mml:msup></mml:mrow><mml:mi mathvariant="normal">B</mml:mi></mml:math>and the rate of the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow/><mml:mrow><mml:mn>7</mml:mn></mml:mrow></mml:msup></mml:mrow><mml:mi mathvariant="normal">Be</mml:mi><mml:mo>(</mml:mo><mml:mi>p</mml:mi><mml:mo>,</mml:mo><mml:mi>γ</mml:mi><mml:mrow><mml:msup><mml:mrow><mml:mo>)</mml:mo></mml:mrow><mml:mrow><mml:mn>8</mml:mn></mml:mrow></mml:msup></mml:mrow><mml:mi mathvariant="normal">B</mml:mi></mml:math>reaction in the Sun

In an effort to better determine the ${}^{7}\mathrm{Be}(p,\ensuremath{\gamma}{)}^{8}\mathrm{B}$ reaction rate, we have performed inclusive and exclusive measurements of the Coulomb dissociation of ${}^{8}\mathrm{B}.$ The former was a study of longitudinal momentum distributions of ${}^{7}\mathrm{Be}$ fragments emitted in the Coulomb breakup of intermediate energy ${}^{8}\mathrm{B}$ beams on Pb and Ag targets. Analysis of these data yielded the $E2$ contribution to the breakup cross section. In the exclusive measurement, we determined the cross section for the Coulomb breakup of ${}^{8}\mathrm{B}$ on Pb at low relative energies in order to infer the astrophysical S factor for the ${}^{7}\mathrm{Be}(p,\ensuremath{\gamma}{)}^{8}\mathrm{B}$ reaction. Interpreting the measurements with first-order perturbation theory, we obtained ${S}_{E2}{/S}_{E1}{=4.7}_{\ensuremath{-}1.3}^{+2.0}\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$ at ${E}_{\mathrm{rel}}=0.6 \mathrm{MeV},$ and ${S}_{17}{(0)=17.8}_{\ensuremath{-}1.2}^{+1.4} \mathrm{eV}\mathrm{}\mathrm{b}.$ Semiclassical first-order perturbation theory and fully quantum mechanical continuum-discretized coupled channels analyses yield nearly identical results for the $E1$ strength relevant to solar neutrino flux calculations, suggesting that theoretical reaction mechanism uncertainties need not limit the precision of Coulomb breakup determinations of the ${}^{7}\mathrm{Be}(p,\ensuremath{\gamma}{)}^{8}\mathrm{B}$ S factor. A recommended value of ${S}_{17}(0)$ based on a weighted average of this and other measurements is presented.

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