Monte Carlo simulation and Boltzmann equation analysis of non-conservative positron transport in H2

Banković, A., Dujko, S., White, R.D., Buckman, S.J., and Petrović, Z.Lj. (2012) Monte Carlo simulation and Boltzmann equation analysis of non-conservative positron transport in H2. Nuclear Instruments & Methods in Physics Research Section B, 279. pp. 92-95.

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Abstract

This work reports on a new series of calculations of positron transport properties in molecular hydrogen under the influence of spatially homogeneous electric field. Calculations are performed using a Monte Carlo simulation technique and multi term theory for solving the Boltzmann equation. Values and general trends of the mean energy, drift velocity and diffusion coefficients as a function of the reduced electric field E/n0 are reported here. Emphasis is placed on the explicit and implicit effects of positronium (Ps) formation on the drift velocity and diffusion coefficients. Two important phenomena arise; first, for certain regions of E/n0 the bulk and flux components of the drift velocity and longitudinal diffusion coefficient are markedly different, both qualitatively and quantitatively. Second, and contrary to previous experience in electron swarm physics, there is negative differential conductivity (NDC) effect in the bulk drift velocity component with no indication of any NDC for the flux component. In order to understand this atypical manifestation of the drift and diffusion of positrons in H2 under the influence of electric field, the spatially dependent positron transport properties such as number of positrons, average energy and velocity and spatially resolved rate for Ps formation are calculated using a Monte Carlo simulation technique. The spatial variation of the positron average energy and extreme skewing of the spatial profile of positron swarm are shown to play a central role in understanding the phenomena.

Item ID: 22306
Item Type: Article (Research - C1)
ISSN: 1872-9584
Keywords: positrons, hydrogen, Monte Carlo, Boltzmann equation, transport coefficients, Ps formation, non-conservative collisions
Additional Information:

This paper appears in the special issue: Proceedings of the Fifth International Conference on Elementary Processes in Atomic Systems Belgrade, Serbia, 21-25 June 2011 edited by Bratislav Marinković and Károly Tőkési.

Date Deposited: 11 Jul 2012 09:37
FoR Codes: 02 PHYSICAL SCIENCES > 0202 Atomic, Molecular, Nuclear, Particle and Plasma Physics > 020201 Atomic and Molecular Physics @ 80%
02 PHYSICAL SCIENCES > 0202 Atomic, Molecular, Nuclear, Particle and Plasma Physics > 020204 Plasma Physics; Fusion Plasmas; Electrical Discharges @ 20%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970102 Expanding Knowledge in the Physical Sciences @ 100%
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