Improved Slow-Positron Yield using a Single Crystal Tungsten Moderator

A. Vehanen, K. G. Lynn, P. J. Schultz, Morten Mostgaard Eldrup

    Research output: Contribution to journalJournal articleResearchpeer-review


    A well-annealed W(110) single crystal was used as a fast-to-slow positron moderator. The measured moderator efficiency at room temperature using a58Co positron source in the backscattering geometry isɛ =(3.2±0.4)×10−3, roughly a factor of three better thanɛ for the best previously reported Cu(111)+S moderator. We find a stable positron moderation efficiency over a period of several weeks when maintained at pressures around 10−9 Torr and an energy spreadΔE = 0.7 eV of the emitted slow positrons. An initial attempt was made to fabricate a hybrid Cu on W(110) moderator, which yieldedɛ of about 1.2×10−3 after annealing.
    Original languageEnglish
    JournalApplied Physics A: Materials Science & Processing
    Issue number3
    Pages (from-to)163-167
    Publication statusPublished - 1983


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