Positron spur structure emulated by variable energy slow positron beam

Abstract

Variable energy slow positron beam was used to probe the positronic spur processes in polymers: low density polyethylene and a polyimide (Kapton). A fraction of the injected positrons was re-emitted as positron or positronium, whose fraction was dependent on the energy of injected positrons. The energy of the re-emitted positrons could become quite large, even larger than the band-gap energies of the substance. This was considered to be the result of charge-up effect. This effect may provide a new concept for a «field assisted slow positron moderator»