Brightness enhancement of slow positron beams
The brightness of slow positron beams can be enhanced significantly by repeated stages of moderation, acceleration and focusing. Presently available data suggest that the source spot area should decrease by 10−4 after each stage with only a modest loss of intensity. Beams with very small angular divergence, which could be made with this technique, would be useful for characterizing surfaces by positron diffraction and microscopy. Using such beams it is possible to envision the study of new exotic systems such as thee +-e − plasma and the positronium molecule.
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- 2.For a recent review see S.Berko, K.F.Canter, A.P.Mills, Jr.: InProgress in Atomic Spectroscopy Part B, ed. by W.Hanle and H.Kleinpoppen (Plenum Press, New York 1979) p. 1427Google Scholar
- 7.The use of non-conservative forces to overcome the limitations of Liouville's theorem has found application in light collection from scintillators by wavelength shifting light pipes. [W.A.Schurcliff: J. Opt. Soc. Am.41, 209 (1951); R.L.Garwin: Rev. Sci. Instrum.31, 1010 (1960).] A similar technique for electrons could make use of negative electron affinity GaAs (CsO) surfaces. If a suitable moderator for ultracold neutrons  can be found, this would be another field which could benefit from brightness enhancementGoogle Scholar
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- 12a.A.P.Mills, Jr.: Appl. Phys. (to be published)Google Scholar