Measurements of the ¹³C(, n) ¹⁶O cross section up to E=8 MeV

We present results from direct measurements of the total C-13(alpha, n) O-16 cross section over laboratory energies E-alpha = 2.9-8.0 MeV, performed with the (HeBF3)-He-3 giant barrel neutron detector at the Edwards Accelerator Laboratory. The cross sections reported in this work are considerably lower than prior direct measurements for E-alpha > 5 MeV, in agreement with prior corrections based on Hauser-Feshbach estimates. However, applying branching ratios based on Hauser-Feshbach estimates to our data would not reproduce existing direct measurements for partial decay channels. This indicates both the promise and limitations of Hauser-Feshbach for branching ratio estimates of (alpha, n) reactions on light nuclides. The C-13(alpha, n) thick-target yields inferred from this work for E-alpha > 6 MeV are significantly larger than those currently employed in estimates of dark matter and neutrino detector backgrounds.