Production of slow positrons using an electron linac

Intense pulsed slow-positron beams have been produced using electron linac beams of energy 25 MeV. Slow positorons were counted by complete separation from strong flashed signals produced directly by the primary electron pulsed beam. The yield of low-energy positrons was estimated as 2x106 slow positrons per second. The conversion efficiency of slow-positron production for 25 MeV electrons, epsilon, was 2.4x10-8, much lower than the value obtained by Howell et al. Several methods of overcoming the difficulties of practical application were attempted, and are discussed in the paper. (author)