The threshold energy of the ${\mathrm{O}}^{16}(d, n){\mathrm{F}}^{17}$ reaction has been measured in an absolute manner with a 2-meter radius electrostatic analyzer. The value, obtained from the intercept of the plot of ${\left(\mathrm{net}\mathrm{neutron}\mathrm{counts}\right)}^{\frac{2}{3}}$ as a function of bombarding energy, is 1829.2±0.6 kev. This threshold energy gives a reaction $Q$ value of -1.6246±0.0005 Mev, a ${\mathrm{F}}^{17}$ mass of 17.007 499 0±0.000 003 2 amu, and a mass excess of 6.9828±0.0030 Mev.

• Received 15 June 1960

DOI:https://doi.org/10.1103/PhysRev.120.889