Trapping positrons for low energy antihydrogen production

Abstract

A method of trapping large numbers of positrons at liquid helium temperatures in a 6 Tesla magnetic field is described. Positrons from a sodium-22 source are moderated to low energies with a tungsten reflection moderator. A Penning trap with hyperbolic electrodes holds the positrons in a magnetron (EXB) orbit. The positrons are then cooled via coupling to a tuned circuit that is in resonance with the axial oscillation of the positrons. At this point, many slow positrons are permanently trapped in the Penning trap. The positrons are centered in the trap by applying a radio-frequency field at a frequency near the sum of the axial and magnetron frequencies. This method promises to produce 106 trapped positrons at a density of 107 to 108 per cm3. Such densities of positrons would be useful in producing antihydrogen in combination with existing antiproton plasmas.