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The improved Fock-Tani T-matrix element for the electron-capture in positive ion-hydrogen atom collision and a second-order Born correction

Thesis/Dissertation ·
OSTI ID:5828915

The Fock-Tani Hamiltonian is obtained by a unitary transformation of the second-quantized Hamiltonian. It describes all the composites explicitly in the unperturbed terms, and the perturbed terms correspond to the true interaction of the scattering-reactive processes. This is very convenient to apply to any scattering or rearrangement channel. The improved Fock-Tani transition amplitude for rearrangement collisions, resulting from the addition of the new generators to satisfy the subsidiary condition for nonzero density systems, completely eliminates the post and prior discrepancy, which is more physical when the three particles approach the collision region. A d-matrix method and diagram formalism is used to check the transformation. The author has applied the symmetrical T-matrix to calculate the cross sections of the electron transfer between the positive ion (proton or positron) and the hydrogen atom for final ground state and excited n= 2 states. The results show a good agreement with the experimental data and with the other theoretical works. In addition, the cross sections from the post and prior amplitudes are compared. Some dominant second Born terms in the range of low and intermediate energies are included in which the author the plane waves for the free ion and the translational part of the bond atom plus the bound ground state as the intermediate state. Twelve dimensional integrals can be reduced to three dimensions, and the complex singularities coming from the Green's operators are removed by means of the Feynman parameterization and Dalitz's method. It was found that the second-order terms have a large effect at large angles.

Research Organization:
Oregon Univ., Eugene, OR (USA)
OSTI ID:
5828915
Country of Publication:
United States
Language:
English