Total-cross-section measurements for positron and electron scattering by O2, CH
Total-cross-section measurements for positron and electron scattering by O2, CH
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O2、CH 正电子和电子散射的总截面测量
DOI：
10.1103/physreva.38.1207
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发表时间：
1988
期刊：
影响因子：
--
通讯作者：
M. N. Uddin
中科院分区：
文献类型：
--
作者：
M. Dababneh;Y. Hsieh;W. Kauppila;C. Kwan;Steven J. Smith;T. Stein;M. N. Uddin
用束透射技术测量了1--500 eV正电子和电子被O/sub ~ 2/，CH/sub ~ 4/和SF/sub ~ 6/散射的总截面（Q/sub ~ T/s）。对于每种靶气体，将正电子Q/sub T/'s与相应的电子Q/sub T/'s进行比较。发现正电子的Q/sub T/s一般低于电子的结果。在低能量下的正电子散射中没有观察到与从各种分子（如SF/sub 6/）散射的电子所观察到的窄形状共振相当的突出结构。CH/sub 4/的正电子Q/sub T/曲线在其正电子偶素形成阈值附近显示出显著的增加，而O/sub 2/和SF/sub 6/曲线在此附近单调增加。在最高的能量调查，有迹象表明，合并的正电子和电子Q/子T/的这些气体的趋势。有趣的相似之处被发现在本正电子和电子Q/sub T/曲线CH/sub 4/与以前的比较测量氩的比较。
Total cross sections (Q/sub T/'s) have been measured for 1--500-eV positrons and electrons scattered by O/sub 2/, CH/sub 4/, and SF/sub 6/ using a beam-transmission technique. The positron Q/sub T/'s are compared with the corresponding electron Q/sub T/'s for each target gas. It is found that the positron Q/sub T/'s are, in general, lower than the electron results. There are no prominent structures observed for positron scattering at low energies that would be comparable to the narrow shape resonances observed for electrons scattering from various molecules, such as SF/sub 6/. The positron Q/sub T/ curve for CH/sub 4/ reveals a significant increase in the vicinity of its positronium formation threshold, while the O/sub 2/ and SF/sub 6/ curves are monotonically increasing in this vicinity. At the highest energies investigated, there are indications of a tendency toward merging of the positron and electron Q/sub T/'s for these gases. Interesting similarities are found in a comparison of the present positron and electron Q/sub T/ curves for CH/sub 4/ with prior comparison measurements for argon.