Development and applications of time-bunched and velocity-selected positron beams

We describe the development of an instrument for the production of low energy positron beams that are bunched in time, and the use of a velocity selection device. The bunching unit was constructed from forty seven separate elements, coupled in series in a capacitor chain to reduce the delay time for...

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Veröffentlicht in:Review of scientific instruments 2003-07, Vol.74 (7), p.3284-3292
Hauptverfasser: Merrison, J. P., Charlton, M., Aggerholm, P., Knudsen, H., van der Werf, D. P., Clarke, J., Poulsen, M. R.
Format: Artikel
Sprache:eng
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Zusammenfassung:We describe the development of an instrument for the production of low energy positron beams that are bunched in time, and the use of a velocity selection device. The bunching unit was constructed from forty seven separate elements, coupled in series in a capacitor chain to reduce the delay time for propagation of the applied voltage pulse along the electrode system and to facilitate operation at frequencies up to 100 kHz. A parabolic potential distribution for time focusing was used. Tests with a dc positron beam produced from a radioactive source are described, together with measurements in which the buncher was used to compress positron pulses produced from an electron accelerator-based beam. Computer simulations of particle trajectories in the buncher have been performed resulting in a detailed evaluation of the factors that govern and limit the time resolution of the instrument. A sector magnet used to velocity-select intermediate energy positrons is described and its performance discussed.
ISSN:0034-6748
1089-7623
DOI:10.1063/1.1581390