We directly measure the absolute cross section of ${}^{11}\mathrm{B}(p,\gamma ){}^{12}\mathrm{C}$ in the energy region of $E_{\mathrm{c}.\mathrm{m}.}=130$–257 keV by using a thin target for the first time. This work is performed on a 320-kV platform at the Institute of Modern Physics in Lanzhou. The astrophysical $S$ factors of this reaction are obtained for capture to the ground and first excited states of ${}^{12}\mathrm{C}$. The properties of the known resonance at $\sim 150$ keV are derived and agree with the previous results. However, in the energy region of 170–240 keV, our $S$ factors are about 15%–50% larger than the adopted values in NACRE II and are also larger than the upper limits of NACRE II by up to $\sim 20\%$. This indicates that our new reaction rate is enhanced by about 15%–50% compared to the NACRE II adopted rate in the temperature region 0.32–0.62 GK.

• Received 5 February 2016
• Revised 16 March 2016

DOI:https://doi.org/10.1103/PhysRevC.93.055804