Total-cross-section measurements for positrons and electrons colliding with H2, N2, and CO2
Total-cross-section measurements for positrons and electrons colliding with H2, N2, and CO2
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正电子和电子与 H2、N2 和 CO2 碰撞的总截面测量
DOI：
10.1103/physreva.25.1393
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发表时间：
1982
影响因子：
2.9
通讯作者：
T. Stein
中科院分区：
文献类型：
--
作者：
K. Hoffman;M. Dababneh;Y. Hsieh;W. Kauppila;V. Pol;J. H. Smart;T. Stein
使用束传输技术在同一装置中测量了正电子和电子与 H/sub 2/、N/sub 2/ 和 CO/sub 2/ 碰撞的总散射截面。射弹冲击能量范围为 1--500 eV（e/sup +/-H/sub 2/）、2--500 eV（e/sup -/-H/sub 2/）、0.5--750 eV（e/sup +/-N/sub 2/）、2.2--700 eV（e/sup -/-N/sub 2/）、0.5--60 eV 用于 e/sup +/-CO/sub 2/，2--50 eV 用于 e/sup -/-CO/sub 2/。通过正电子在各自的正电子素形成阈值处与每个分子碰撞的总横截面的突然上升，可以清楚地看到正电子素形成的开始。将 H/sub 2/ 和 N/sub 2/ 的正电子测量值与中间能量的电子测量值进行比较。该比较揭示了 H/sub 2/ 在高于 200 eV 的能量下横截面的合并，而对于 N/sub 2/ 在所有能量下电子结果仍然高于正电子结果。对潜在的实验误差以及以小前角散射的弹丸进行区分的实验分辨率进行了估计。
Total scattering cross sections have been measured in the same apparatus for positrons and electrons colliding with H/sub 2/, N/sub 2/, and CO/sub 2/ using a beam transmission technique. The projectile impact energies range from 1--500 eV for e/sup +/-H/sub 2/, 2--500 eV for e/sup -/-H/sub 2/, 0.5--750 eV for e/sup +/-N/sub 2/, 2.2--700 eV for e/sup -/-N/sub 2/, 0.5--60 eV for e/sup +/-CO/sub 2/, and 2--50 eV for e/sup -/-CO/sub 2/. The onset of positronium formation is clearly seen by an abrupt rise in the total cross sections for positrons colliding with each of the molecules at the respective positronium-formation thresholds. The positron measurements are compared with the electron measurements at intermediate energies for H/sub 2/ and N/sub 2/. This comparison reveals a merging of the cross sections for H/sub 2/ at energies above 200 eV, while for N/sub 2/ the electron results remain higher than the positron results at all energies. Estimates are made of potential experimental errors, as well as the experimental resolution for discrimination against projectiles scattered at small forward angles.