Showing papers by "Eric M. Gullikson published in 1986"
TL;DR: In this paper, it was shown that solid Ne makes a more efficient moderator than any other material known to date, achieving an efficiency of (0.30±0.02)% for a flat layer of Ne covering a 22Na deposit.
Abstract: Slow positrons can be obtained by moderating the energetic β+ particles from a radioactive source. We find that solid Ne makes a more efficient moderator than any other material known to date. The efficiency e, defined as the number of slow positrons per β+ emitted by the source, is (0.30±0.02)% for a flat layer of Ne covering a 22Na deposit. In a cylindrical geometry, e is (0.70±0.02)%, more than twice the previous best efficiency obtained with single‐crystal tungsten. The energy spectrum for Ne has a full width at half‐maximum of 0.58 eV, somewhat broader than the spectrum of positrons from a single‐crystal metal. Moderators made from the other solid rare gases have a much lower efficiency and a larger energy spread.
223 citations
TL;DR: Estimation de la vitesse de perte d'energie et du libre parcours moyen du positon et determination des seuils inelastiques correspondant a la formation d'exciton, de paire electron-trou et de positonium dans Ne, Ar, Kr and Xe solides, a partir de mesures de the distribution de l'ener energy de positons reemis.
Abstract: Estimation de la vitesse de perte d'energie et du libre parcours moyen du positon et determination des seuils inelastiques correspondant a la formation d'exciton, de paire electron-trou et de positonium dans Ne, Ar, Kr et Xe solides, a partir de mesures de la distribution de l'energie de positons reemis, utilisant un faisceau de positons lent sous ultravide. Interpretation satisfaisante des resultats par un modele de positon chaud
59 citations