Development of a cone-geometry positron moderator

Lynn, K. G.; Gramsch, E.; Usmar, S. G.; Sferlazzo, P.
July 1989
Applied Physics Letters;7/3/1989, Vol. 55 Issue 1, p87
Academic Journal
Results are presented on a new cone-shaped positron moderator which shows a high moderator efficiency (i.e., conversion of beta decay to emitted slow positrons). The moderator efficiencies for the cone moderators studied were found to be up to 0.14% compared to thin-foil measurements of 0.06% in the same experimental system including identical source and holder. These moderators are rugged and easily fabricated, however, they have a lower brightness than single-crystal foil moderators. Comparison of various geometries is presented as well as suggestions for further improvements to increase the total efficiencies.


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