Direct measurement of the parapositronium lifetime in alpha-SiO2.
Direct measurement of the parapositronium lifetime in alpha-SiO2.
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DOI：
10.1103/physrevlett.90.193401
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发表时间：
2003-05
影响因子：
8.6
通讯作者：
H. Saito;T. Hyodo
中科院分区：
文献类型：
--
作者：
H. Saito;T. Hyodo
利用一台新研制的基于BaF_2晶体和快速数字示波器的正电子寿命谱仪，首次直接测定了α-SiO_2中离域仲正电子素的平均寿命。其寿命为156+/-4ps，比其本征寿命125 ps长得多。这清楚地表明，在α-SiO2中对正电子偶素的主要多体效应是介质中的电子对组成粒子之间的库仑相互作用的屏蔽，并且正电子偶素中的电子和正电子之间的平均距离变得大于其真空值。
The mean lifetime of delocalized parapositronium in alpha-SiO2 has been determined directly for the first time using a newly developed positron lifetime spectrometer based on BaF2 scintillators and a fast digital oscilloscope. The lifetime is found to be 156+/-4 ps, which is much longer than its intrinsic lifetime of 125 ps. This indicates clearly that the primary many-body effect on positronium in alpha-SiO2 is the screening of the Coulomb interaction between the constituent particles by electrons of the medium and that the average distance between the electron and positron in positronium becomes larger than its vacuum value.