LOW-ENERGY POSITRON INJECTOR

Abstract

The LEPTA low-energy positron accumulator, which is to be used for producing directed fluxes of positronium and antihydrogen atoms, is under development at the Joint Institute of Nuclear Research. The monochromatic positron injector, operating in the pulsed mode, in the accumulator must generate a positron beam with intensity 10 8 ‐10 9 particles in a pulse with duration less than 300 nsec, the positron energy is 10 keV, the relative energy spread in the beam is less than 2·10 ‐3 , and the beam radius is 0.5 cm. Radioactive 22 Na serves as a positron source. The positrons at the exit from the source are decelerated in a solid target and enter the magnetic trap. There they are once again decelerated in a gas to thermal velocity and accumulate in ~100 sec. For injection into the accumulator, the positrons are pulled out of the trap by a pulsed electric field and acclerated up to the required energy.