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This talk will present numerical and analytic studies of antihydrogen formation via radiative and three-body recombination of stationary antiprotons in a strongly magnetized pure positron plasma[1]. A classical Monte-Carlo calculation has been used to determine the collisional energy transition rate between excited atomic states. These transition rates are used to determine the mean collisional energy loss rate for an ensemble of weakly-bound atoms, assuming the ensemble ergodically populates available states. The rate decreases with increasing binding energy, but is larger than expected from dimensional arguments because of collisional drag on the E×B drift motion of the bound positron. The transition rates are also used in a numerical solution of the Master Equation for the collisional evolution of the energy distribution of bound atoms. Power law tails are observed at deep binding in the energy distribution, similar to those observed in previous simulations. The T9/2 temperature scaling expected for the equilibrium flux to deep binding (i.e. the equilibrium recombination rate) is not observed in these nonequilibrium power law tails. Rather, the observed nonequilibrium flux at deep binding is nearly independent of temperature. For atoms that enter the chaotic regime, radiation takes over as the dominant recombination mechanism. Estimates of the radiative energy loss rate will also be presented. The distribution of magnetic moments will also be discussed.
*Supported by grants from the National Science Foundation and Department of Energy. 1) Eric Bass and DHE Dubin, Phys. Plasmas 16, 012101 (2009). |
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