Slow positron beams generally employ a radioactive β+ emitter with a crystal moderator in which the positrons thermalize. A small fraction of the thermalized positrons are desorbed at low (1–3 eV) energy, characteristic of the positron work function in the crystal. The energy width of the emitted positrons from W(110) and Ni(111) moderators can be narrowed significantly by cooling to liquid N2 temperatures. A practical configuration for a cooled moderator positron gun is presented which produces a narrow energy positron beam with good efficiency.
No takes yet. Share an insight, caveat, or question.
Brown et al. (1986) studied this question.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: