Compound-Nucleus and DeuteronD-State Effects Observed in theT20Analyzing Power of (d,p) Reactions

The tensor-analyzing power $T_{20}$ of ($d,p$) reactions on ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$, ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$, and ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$ are measured at small angles as a function of bombarding energy. Measurements are carried out for ${\theta }_{\mathrm{lab}}$ from 0-15° and $E_d$ from 5-12 MeV. Strong fluctuations of $T_{20}$ with energy are observed. The measurements are not explained by distorted-wave calculations which neglect the deuteron $D$ state. Inclusion of the $D$ state leads to better agreement with the data. The remaining discrepancy between the $D$-state calculation and the measured $T_{20}$ can be explained by a compound-nucleus contribution to the reaction mechanism.