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Positronium annihilation in silica aerogel studied by a positron age-momentum correlation technique

Positronium annihilation in silica aerogel studied by a positron age-momentum correlation technique
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摘要 A high-performance positron age-momentum correlation (AMOC) spectrometer was newly developed. The counting rate is increased up to 200 cps much larger than the value 20 cps reported by other international groups. And at the same time, the time resolution still keeps at the international level of 220 ps. Furthermore, positronium (Ps) annihilation in silica aerogel was investigated by AMOC, which indicates: (1) Ps annihilation between the grains dominantly undergoes pick-off process and spin conversion from o-Ps to p-Ps; (2) Annealing below 400 ℃ changes the grain surface conditions, i. e. the desorption of hydrogen and the decrease of the defect centers concentration. A high-performance positron age-momentum correlation (AMOC) spectrometer was newly developed. The counting rate is increased up to 200 cps much larger than the value 20 cps reported by other international groups. And at the same time, the time resolution still keeps at the international level of 220 ps. Furthermore, positronium (Ps) annihilation in silica aerogel was investigated by AMOC, which indicates: (1) Ps annihilation between the grains dominantly undergoes pick-off process and spin conversion from o-Ps to p-Ps; (2) Annealing below 400 ℃ changes the grain surface conditions, i. e. the desorption of hydrogen and the decrease of the defect centers concentration.
出处 《Chinese Physics C》 SCIE CAS CSCD 2009年第1期81-84,共4页 中国物理C(英文版)
基金 Supported by NSFC (10575112, 10705031, 60606011)
关键词 positron age-momentum correlation positronium formation positron states silica aerogel positron age-momentum correlation, positronium formation, positron states, silica aerogel
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参考文献11

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