We have measured the cross section for the important fusion-energy reaction ${}_{}{}^2{}_{}{}^{}\mathrm{H}(\mathrm{t},\alpha )\mathrm{n}$ at 17 energies over the triton bombarding energy range of 12.5-117 keV. This corresponds to an equivalent deuteron bombarding energy range of 8.3-78.1 keV and to a plasma temperature ($\mathrm{kT}$) range of 0.7-18.8 keV. The cross section is accurate to 1.4% over most of the energy range, with the error rising to 4.8% at the lowest energy. These data are considerably more accurate than the previous d + t measurements in this energy range. We compare our data with those of other measurements and with an existing $R$-matrix analysis of the mass-5 system. We have also performed a single-level $R$-matrix analysis of a restricted data base that contains our data and have used that analysis to compute Maxwellian reactivities up to a plasma temperature of 20 keV. In addition, for calibration purposes, we measured to better than 1% absolute error the ${}_{}{}^2{}_{}{}^{}\mathrm{H}$(p,p)${}_{}{}^2{}_{}{}^{}\mathrm{H}$ elastic differential cross section at six laboratory angles at a proton bombarding energy of 10.04 MeV.

• Received 13 March 1984

DOI:https://doi.org/10.1103/PhysRevC.29.2031