Eur. Phys. J. D (2012) 66: 108
https://doi.org/10.1140/epjd/e2012-20668-5

Regular Article

Pick-off quenching probability of ortho-positronium per collision with atoms and molecules

¹ Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, 305-0801 Ibaraki, Japan
² Institute of Physics, Graduate School of Arts and Sciences, University of Tokyo, 3-8-1 Komaba, Meguro, 153-8902 Tokyo, Japan
³ Faculty of Health Sciences, Yamaguchi University School of Medicine, 1-1-1 Minami-Kogushi, Ube, 755-8554 Yamaguchi, Japan

^a e-mail: ken.wada@kek.jp

Received: 17 November 2011
Received in final form: 1 March 2012
Published online: 30 April 2012

Abstract

Positronium quenching through its collisions with gaseous atoms and molecules is discussed. It is found that the values of the normalized pick-off quenching parameter, ¹Z_eff, at room temperature are roughly proportional to the geometric collisional cross-sections estimated from the radius of the positronium and those of the atoms and molecules derived from the viscosity. This suggests that the probabilities of the pick-off quenching of the thermalized positronium per collision with various atoms and molecules are almost constant.