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Second order Born calculation for charge transfer

Thesis/Dissertation ·
OSTI ID:6209200
Charge transfer cross sections, from the ground state of the target to the ground state of the projectile, have been computed in a second order Born approximation for protons incident upon hydrogen at energies of 1, 10, and 50 MeV. The exact second order matrix element is evaluated numerically, and the results are compared to a standard peaking approximation (SP), as well as to a new peaking approximation (LP) developed herein. At 50 MeV two distinct second order effects are evident in the differential cross section. For very small (center of mass) scattering angles (THETA approx. = .032/sup 0/) the second order cross section is smaller than the first order cross section, while at larger angles (THETA approx. = .054/sup 0/) a second Born peak occurs. This peak can be kinematically associated with a classical two step process which gives rise to the well known dominating v/sup -11/ asymptotic velocity dependence of the total cross section. The reduction of the differential cross section at smaller angles serves to decrease the total cross section, as is predicted by the asymptotic expression. At 10 MeV second order effects become less important, and at 1 MeV the kinematic peak has all but disappeared, while the second order cross section has here become larger than the first order cross section. At intermediate energies experimental results indicate that the first order cross section used here is itself too large.
Research Organization:
Kansas State Univ., Manhattan (USA)
OSTI ID:
6209200
Country of Publication:
United States
Language:
English