Effective cross sections for anisotropic collisional relaxation of polarization moments of excited hydrogen atoms with allowance for the fine structure and the lamb shift

Based on numerical integration of equations of the impact-parameter method, effective cross sections are calculated for the processes of anisotropic c ollisional relaxation of polarization moments for a group of energy levels of excited hydrogen atoms with the principal quantum number n = 2 in collis ions with a beam of slow protons. The calculations are carried out for a fu ll potential of interaction of colliding particles, taking into account the fine structure and the Lamb shift of energy levels. In spite of its small magnitude, it is the Lamb shift that makes values of the effective cross se ctions finite by removing the logarithmic divergence of integrals with resp ect to an impact parameter. On account of real values of the fine-structure splitting and the Lamb shift, it is necessary to integrate numerically the system of equations of the impact-parameter method for tens of thousands o f impact parameter values over a region extending up to 10(5) au. An analys is is given for all symmetry- allowed processes of joint anisotropic collis ional relaxation of polarization moments p(q)(kappa) for the group of hydro gen levels with n = 2, which occur with the conservation of projections q o f these moments on a beam of incident charged particles but with a possible mixing of their ranks kappa. Numerical values obtained for the effective c ross sections allow us to calculate quantitatively these processes of relax ation and their optical manifestations-destruction, interconversion, and ge neration of the linear and circular polarization of light under the action of anisotropic collisions, as well as the beats of polarizations of light i nduced by such collisions.