Monte Carlo study of coherent scattering effects of low-energy charged particle transport in Percus-Yevick liquids

Abstract

We generalize a simple Monte Carlo (MC) model for dilute gases to consider the transport behavior of positrons and electrons in Percus-Yevick model liquids under highly non-equilibrium conditions, accounting rigorously for coherent scattering processes. The procedure extends an existing technique [Wojcik and Tachiya, Chem. Phys. Lett. 363, 3-4 (1992)], using the static structure factor to account for the altered anisotropy of coherent scattering in structured material.We identify the effects of the approximation used in the original method, and develop a modified method that does not require that approximation. We also present an enhanced MC technique that has been designed to improve the accuracy and flexibility of simulations in spatially-varying electric fields. All of the results are found to be in excellent agreement with an independent multiterm Boltzmann equation solution, providing benchmarks for future transport models in liquids and structured systems.

Benchmark for the Determination of the Positronium Formation Fraction in Interstellar Media

“…These codes have been developed independently by us and provide a consistency check. One of these codes has been verified against several other benchmarks (Ness & Robson 1986;Reid 1979;Tattersall et al 2015) for steady-state transport of electrons in gases and liquids.…”

“…In short, the codes select a random initial energy for the positron from a normal distribution. During the propagation of the positron, it undergoes a series of collisions, determined by randomly sampling the time to collision (Tattersall et al 2015) from the collision frequency ν(ε)=n 0 vσ(ε). These collisions shift the positron toward lower energies, and the simulation is stopped when the positron either forms Ps or falls below the Ps threshold ε Ps .…”

Simulating the Feasibility of Using Liquid Micro-Jets for Determining Electron–Liquid Scattering Cross-Sections

“…LµJs inherently require specific and precise spatial variation in terms of the neutral density, and hence, an MC simulation is well suited for the task. The simulation technique is discussed in detail in [ 47 ], hence, here, we detail its application to LµJs, while a section of benchmark results is presented in Appendix A .…”

“…Utilising a similar NN methodology, along with energy loss spectra from a LµJ experiment, we propose the generation of cross-section sets for electrons within a liquid environment. To facilitate this, a benchmarked Monte Carlo simulation technique, for simulating electron transport in liquid environments [ 47 ], has been developed and implemented for this study, with extensions to calculate EELS arising from the scattering of electrons from an LµJ.…”

Unified solution of the Boltzmann equation for electron and ion velocity distribution functions and transport coefficients in weakly ionized plasmas

“…For all regimes, we focus on convergence of the solution, quantified by the transport quantities and the distribution function F 1 (v). These are compared with identical quantities sampled from Monte-Carlo (MC) simulations, which have been extensively benchmarked [27] and include temperature effects of the neutral background [28].…”