Low-energy cross section of the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mmultiscripts><mml:mi mathvariant="normal">Be</mml:mi><mml:mprescripts/><mml:none/><mml:mrow><mml:mn>7</mml:mn></mml:mrow></mml:mmultiscripts></mml:math>(<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>p</mml:mi><mml:mo>,</mml:mo><mml:mi>γ</mml:mi></mml:mrow></mml:math>)<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mmultiscripts><mml:mi mathvariant="normal">B</mml:mi><mml:mprescripts/><mml:none/><mml:mrow><mml:mn>8</mml:mn></mml:mrow></mml:mmultiscripts></mml:math>solar fusion reaction from the Coulomb dissociation of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mmultiscripts><mml:mi mathvariant="normal">B</mml:mi><mml:mprescripts/><mml:none/><mml:mrow><mml:mn>8</mml:mn></mml:mrow></mml:mmultiscripts></mml:math>

An exclusive measurement of the Coulomb breakup of $^{8}\mathrm{B}$ into $^{7}\mathrm{Be}$$+p$ at 254A MeV was used to infer the low-energy $^{7}\mathrm{Be}$($p,\ensuremath{\gamma}$)$^{8}\mathrm{B}$ cross section. The radioactive $^{8}\mathrm{B}$ beam was produced by projectile fragmentation of 350A MeV $^{12}\mathrm{C}$ and separated with the FRagment Separator (FRS) at Gesellschaft f\"ur Schwerionenforschung in Darmstadt, Germany. The Coulomb-breakup products were momentum-analyzed in the KaoS magnetic spectrometer; particular emphasis was placed on the angular correlations of the breakup particles. These correlations demonstrate clearly that $E1$ multipolarity dominates within the angular cuts selected for the analysis. The deduced astrophysical ${S}_{17}$ factors exhibit good agreement with the most recent direct $^{7}\mathrm{Be}$($p,\ensuremath{\gamma}$)$^{8}\mathrm{B}$ measurements. By using the energy dependence of ${S}_{17}$ according to the recently refined cluster model for $^{8}\mathrm{B}$ of P. Descouvemont [Phys. Rev. C 70, 065802 (2004)], we extract a zero-energy S factor of ${S}_{17}(0)=20.6\ifmmode\pm\else\textpm\fi{}0.8(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}1.2(\mathrm{syst})$ eV b. These errors do not include the uncertainty of the theoretical model to extrapolate to zero relative energy, estimated by Descouvemont to be about 5%.

Hali tarjima qilinmagan