Application of Recoil Techniques to Study of the ReactionsRa226(α, 4n)Th226,Pb208(α, 2n)Po210, andPb207(α, n)Po210

Abstract

The ranges and angular distributions of the recoiling residual nuclei from the systems ${\mathrm{Ra}}^{226}(\alpha , 4n){\mathrm{Th}}^{226}$, ${\mathrm{Pb}}^{208}(\alpha , 2n){\mathrm{Po}}^{210}$, and ${\mathrm{Pb}}^{207}(\alpha , n){\mathrm{Po}}^{210}$ have been examined to obtain information about the reaction mechanisms. The experimental angular distributions were compared with distributions calculated by a Monte Carlo method based upon the compound nucleus and statistical models. The results from the ${\mathrm{Ra}}^{226}(\alpha , 4n)$ reactions are in agreement with the calculations; the ${\mathrm{Pb}}^{208}(\alpha , 2n)$ and ${\mathrm{Pb}}^{207}(\alpha , n)$ data require substantial contributions from direct-interaction mechanisms.