The ${}^{10}\mathrm{B}\left(\vec{p},\gamma \right){}^{11}\mathrm{C}$ reaction was studied by detecting the $\gamma$-rays produced when 100-, 130-, and $160\text{−}\text{keV}$ polarized protons were stopped in a thick ${}^{10}\mathrm{B}$ target. Polarized and unpolarized incident beams were used to measure the cross section and vector analyzing power as a function of angle and energy for capture to the ground $\left(J^{\pi }=3∕2^{-}\right)$, the second $\left(E=4319\mathrm{keV},J^{\pi }=5∕2^{-}\right)$, and the fifth $\left(E=6478\text{keV},J^{\pi }=7∕2^{-}\right)$ excited states of ${}^{11}\mathrm{C}$. The data were analyzed to obtain the amplitudes and phases of the contributing transition-matrix elements at each measured energy for all three transitions. Values of the astrophysical $S$ factors were obtained from the cross section data and are compared to previous results. A direct capture plus resonance model calculation was performed in an attempt to account for all measured quantities. It was found that the large $\left(\sim 32\%\right)$ value of $A_y\left(90°\right)$ observed in the case of capture to the ground state could be accounted for by including the sub-threshold resonance at $8420\text{keV}$.

• Received 23 April 2003

DOI:https://doi.org/10.1103/PhysRevC.68.045803