Antiproton and proton collisions with the alkali-metal atoms Li, Na, and K

Single-electron ionization and excitation cross sections as well as cross sections for excitation into the first excited p state of the alkali-metal atoms Li(2s), Na(3s), and K(4s) colliding with antiprotons and protons were calculated using a time-dependent channel-coupling approach. For antiprotons an impact-energy range from 0.25 to 1000 keV and for protons from 2 to 1000 keV was considered. The target atoms are treated as effective one-electron systems using a model potential. The results are compared with theoretical and experimental data from literature and calculated cross sections for antiproton-hydrogen collisions. For proton collisions a good overall agreement is found that confirms the present numerical approach, whereas discrepancies are found between the present antiproton cross sections and those calculated by Stary et al.