Calculated Born and four-state cross sections of low lying Ar levels excited by proton and electron impact

The excitation of (3p) 5 4s and (3p) 5 4p levels of Ar is investigated by use of the Born approximation and a four-state calculation including 1 S 0 (3p) 6 , 1 S 0 (3p) 5 4p and P 1 (3p) 5 4s (M=0,1). HF-type wavefunctions are used. The spin-orbit coupling is treated in a rather semiempirical way.