Formation of antihydrogen beams from positron–antiproton interactions

Abstract

The formation of a beam of antihydrogen atoms when antiprotons pass through cold, dense positron plasmas is simulated for various plasma properties and antiproton injection energies. There are marked dependences of the fraction of injected antiprotons which are emitted as antihydrogen in a beam-like configuration upon the temperature of the positrons, and upon the antiproton kinetic energy. Yields as high as 13% are found at the lowest positron temperatures simulated here (5 K) and at antiproton kinetic energies below about 0.1 eV. By 1 eV the best yields are as low as 10−3, falling by about two orders of magnitude with an increase of the positron temperature to 50 K. Example distributions for the antihydrogen angular emission, binding energy and kinetic energy are presented and discussed. Comparison is made with experimental information, where possible.