Laser-induced antiproton–positron recombination in traps

Abstract

We present analytical expression for the differential cross-section of laser-induced recombination in positron–antiproton plasma in traps taking into account the polarization of laser radiation, laser beam direction and Zeeman splitting of discrete states. Due to the large magnetic field the Zeeman splitting leads to optical resonances individual for each magnetic sublevel, and the differential cross-section depends on the laser polarization. The interference of the initial states leads to anisotropy of the cross-section dependence on the positron relative velocity direction. Numerical calculations of direct laser-induced recombination rates were made assuming equilibrium velocity distribution of the positrons. It was shown that the laser-induced recombination rate is equal to the spontaneous one at intensities about dozens of W/cm 2. Saturation intensities for the transitions from n=100, 10 to n=3 which can be used for the estimations of the cascade recombination from the continuum or high Rydberg states via states n≈10 are presented also.