(d, p) Reaction on Heavy Elements at Low Deuteron Energies

Deuterons of 9.1, 8.3, and 7.4 Mev were used to produce ($d, p$) reactions in ${\mathrm{Pb}}^{206}$ and ${\mathrm{Bi}}^{209}$ targets. The proton differential cross section was measured for different $Q$ values, each of which corresponds to a final state of known assignment. With one exception, all of the observed angular distributions were broad peaks with maxima near 180°. The theoretical approximations which apply for low deuteron energy predict a Gaussian distribution peaked in the backward direction. Although the measured distributions are not of Gaussian form, a comparison of the measured and predicted width variation with $Q$ shows fair agreement with one theoretical result and poor agreement with the other. For the reaction with the highest $Q\left(\approx 4.5 \mathrm{Mev}\right)$ a peak near 120° was observed. This more forward peak would be expected both from a reduced Coulomb effect and from the influence of the nuclear potential on the proton. As expected when the Coulomb field is dominant, there was only a small observed correlation between the measured angular distribution and the angular momentum of the captured neutron. In a few cases, triton angular distributions from ($d, t$) reactions were measured, and these also showed peaks at large scattering angles.