Doppler-broadening measurements of positronium thermalization in gases
Doppler-broadening measurements of positronium thermalization in gases
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气体中正电子热化的多普勒展宽测量
DOI：
10.1103/physreva.67.022504
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发表时间：
2003
影响因子：
2.9
通讯作者：
D. Gidley
中科院分区：
文献类型：
--
作者：
M. Skalsey;J. Engbrecht;C. Nakamura;R. Vallery;D. Gidley
利用湮灭光子的时间分辨多普勒展宽测量，研究了气体中在几个eV下产生的正电子子（Ps）的形成和随后的热化。在Ps形成后，静态磁场将Ps熄灭，使多普勒能量测量能够在25至70 ns之间进行。改变气体密度可以观察到很大范围的热化过程。研究了七种不同的气体：He、Ne、Ar、H{sub 2}、N{sub 2}、异丁烷和新戊烷。一个经典的弹性散射模型可以很好地拟合所有的气体数据。根据经典模型拟合，确定了每种气体的弹性散射截面和平均Ps地层能量。当可以进行比较时，这些横截面通常比大多数量子力学理论预测和大多数先前使用角相关技术获得的实验结果要小得多。对仪器和分析进行了各种系统的测试，加强了与以往工作的差异。
The formation and subsequent thermalization of positronium (Ps) produced at a few eV in gases are investigated using time-resolved Doppler-broadening measurements of the annihilation photons. A static magnetic field quenches the Ps enabling Doppler energy measurements from 25 to 70 ns after the Ps is formed. Varying the gas density permits a significant range of the thermalization process to be observed. Seven different gases are studied, He, Ne, Ar, H{sub 2}, N{sub 2}, isobutane, and neopentane. A classical elastic scattering model fits all the gas data reasonably well. For each gas, an elastic scattering cross section and an average Ps formation energy are determined from the classical model fit. When comparisons can be made, these cross sections are often significantly smaller than most quantum-mechanical-theory predictions and most previous experimental results obtained using the angular correlation technique. Various systematic tests have been applied to the apparatus and the analysis, reinforcing the discrepancy with previous works.