Eur. Phys. J. D (2014) 68: 4
https://doi.org/10.1140/epjd/e2013-40473-x

Regular Article

Simulation study of indirect positron generation by an ultra-short laser

¹ School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000, P.R. China
² Science and Technology on Plasma Physics Laboratory, Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900, P.R. China

^a e-mail: yanyh05@gmail.com

Received: 5 August 2013
Received in final form: 14 October 2013
Published online: 22 January 2014

Abstract

Positron generation by an ultra-short ultra-intense laser in an indirect manner has been studied with two-dimensional particle-in-cell (PIC) and Monte Carlo (MC) simulations. In this generation scheme, positrons are produced with energetic electrons accelerated by an ultra-shot laser pulse propagating through an underdense plasma. The dependence of the positron beam properties on the plasma length and secondary target (converter) thickness was investigated in detail. The simulation results reveal that the positron yield is strongly correlated with the total energy of laser-accelerated electrons; both the temperature and divergence of the positron beam are sensitive to the plasma length; and the positron beam has a pulse duration comparable to the incident electron beam. In addition, it is indicated that even with the optimal converter thickness, only a small fraction (11.4%) of positrons can escape out and most of the detected positrons originate from the back edge of the converter.