INFLUENCE OF CHANNELING ON SCATTERING OF LOW-ENERGY ANTIPROTONS TRANSMITTED THROUGH THIN-CRYSTALS

A computer simulation study of the transmission of low-energy antiprot ons through a thin single crystal, along one of the axial directions, is reported. The angular distribution of the scattered antiprotons beh ind the crystal is analysed. As an example the scattering of 300 keV a ntiprotons moving along the [110] axis in 500 Angstrom and 2000 Angstr om thick silicon crystal is considered. The results of the calculation show the formation of the ring-shaped patterns (doughnuts) for the in cident angles of the order of the critical angle for channeling. A com parison of the angular distribution of antiprotons with that of proton s is made. It is shown that the randomization of the transverse moment um is much quicker for antiprotons than for protons, which leads to a more uniform azimuthal angular distribution. The blocking effect in th e transverse plane, known for protons, is not found for antiprotons. T he influence of the doughnut distribution on the results of the transm ission experiments with small acceptance angle detectors is discussed.