Singh Suvam, Dutta Sangita, Naghma Rahla, Antony Bobby
Atomic and Molecular Physics Lab, Department of Applied Physics, Indian School of Mines , Dhanbad 826004, India.
J Phys Chem A. 2016 Jul 21;120(28):5685-92. doi: 10.1021/acs.jpca.6b04150. Epub 2016 Jul 5.
A theoretical formalism is introduced in this article to calculate the total cross sections for positron scattering. This method incorporates positron-target interaction in the spherical complex optical potential formalism. The study of positron collision has been quite subtle until now. However, recently, it has emerged as an interesting area due to its role in atomic and molecular structure physics, astrophysics, and medicine. With the present method, the total cross sections for simple atoms C, N, and O and their diatomic molecules C2, N2, and O2 are obtained and compared with existing data. The total cross section obtained in the present work gives a more consistent shape and magnitude than existing theories. The characteristic dip below 10 eV is identified due to the positronium formation. The deviation of the present cross section with measurements at energies below 10 eV is attributed to the neglect of forward angle-discrimination effects in experiments, the inefficiency of additivity rule for molecules, empirical treatment of positronium formation, and the neglect of annihilation reactions. In spite of these deficiencies, the present results show consistent behavior and reasonable agreement with previous data, wherever available. Besides, this is the first computational model to report positron scattering cross sections over the energy range from 1 to 5000 eV.
本文介绍了一种理论形式体系来计算正电子散射的总截面。该方法将正电子与靶的相互作用纳入球形复光学势形式体系中。直到现在，正电子碰撞的研究都相当微妙。然而，最近，由于其在原子和分子结构物理学、天体物理学及医学中的作用，它已成为一个有趣的领域。利用当前方法，获得了简单原子C、N和O及其双原子分子C₂、N₂和O₂的总截面，并与现有数据进行了比较。与现有理论相比，本工作中获得的总截面在形状和大小上更为一致。由于正电子素的形成，在10 eV以下识别出了特征性的凹陷。本截面在能量低于10 eV时与测量值的偏差归因于实验中对前向角分辨效应的忽略、分子加和规则的无效性、正电子素形成的经验处理以及对湮灭反应的忽略。尽管存在这些不足，但本结果在任何可用的情况下都表现出一致的行为，并与先前的数据合理吻合。此外，这是第一个报告能量范围从1到5000 eV的正电子散射截面的计算模型。
