Excitation Function and Recoil Ranges ofAt211Produced ThroughAr40+Bi209Transfer Reactions

The excitation function and projected recoil ranges for ${}_{}{}^{211}{}_{}{}^{}\mathrm{At}$ produced through ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ar}$+${}_{}{}^{209}{}_{}{}^{}\mathrm{Bi}$ reactions have been measured for ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ar}$ beam energies from 190 to 270 MeV. A substantial value (25 mb) was found for the cross section at high energies. The general features of the reaction (excitation function, magnitude of the cross section, variation of recoil range versus incident energy) are very similar to the results for lighter projectiles, and show unambiguously a noncompound-nucleus process. The possibility that various transfer mechanisms may lead to ${}_{}{}^{211}{}_{}{}^{}\mathrm{At}$ is discussed with the help of a kinematic analysis.