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Abstract
The present thesis is an investigation of the scattering of the protons and antiprotons by hydrogen atoms, when the latter are initially in the excited 2p-state. We apply the impact parameter method. The cross sections for excitation to n=3 states are calculated, taking into account the coupling between n=1 , 2 , 3 , and 4 states of the target atom. The first chapter is an introduction in which we give a brief account of a historical background of the ion-atom collision, particularly the interaction of protons and antiprotons-hydrogen atoms. The second chapter includes a brief account on the wave function of the hydrogen atom and the wave-treatment technique. It includes also a discussion of the impact parameter model and calculation of the matrix elements of interaction that has been used in the calculation. The scattering cross section of the protons and antiprotons collision with the hydrogen atoms are expressed in terms of the incomplete Gamma functions and the Clebsh-Gordan coefficients. A number matrix elements corresponding to some hydrogen states are calculated. In the third chapter we discussed the numerical solution of the system of coupled differential equations arising from the impact parameter method. Finally we discuss the results give the figures needing for explaining them. Our main conclusion is that including n=4 states improves the results by reducing the cross-sections. We have also observed that the sign of the projectile charge is important while its influence varies from one channel to another. The effect of the sign of the projectile charge on the 3d excitation cross-sections is greater than its effect on the 3s and 3p ones. However, the effect becomes smaller as the incident energy increases and may asymptotically be neglected, as the calculations converge to the first Born approximation .