Total $L$ x-ray production cross sections of Y and Sn and $M$ x-ray production cross sections of Au and Bi for proton impact have been measured over the projectile-energy range 3.0-40 MeV and the ionization cross sections obtained for these shells are compared with calculations of the plane-wave Born approximation and the binary encounter approximation. The inner-shell ionizations by close and distant collisions are theoretically discussed in terms of the generalized oscillator strength and the contributions from these two kinds of collisions are separately estimated in the framework of the plane-wave Born approximation. Distant collisions in this energy region are not so effective as in the case of $K$-shell ionization, while at a very high energy the two kinds of collisions contribute nearly equally to the ionization. The experimental results show good agreement with the plane-wave Born approximation calculation except for the $M$-shell ionization of Bi.

• Received 25 February 1980

DOI:https://doi.org/10.1103/PhysRevA.22.2536