Electro-produced slow positrons
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During the last 6 years it has been demonstrated that electro-produced intense beams of slow positrons are possible. High energy electrons from an accelerator generate bremsstrahlung in a thick conversion target of high element number Z. The photons produce electronpositron pairs and a small fraction of the positrons may be moderated to thermal energies. A review is given of the existing slow positron beam lines using this technique. At accelerator energies of 100 MeV total conversion efficiencies of several slow positrons per 106 primary electrons have been obtained, resulting in average intensities of several 109 slow positrons per second or more than 105 slow positrons in pulses having a duration of a few ns. A further increase in intensity by at least one order of magnitude seems possible at higher accelerator energies.
KeywordsThin Film Energy Electron Thermal Energy Conversion Efficiency Average Intensity
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