Optimisation of the thickness of the moderator for positron annihilation process study in Ar gas

Toshitaka Oka; Yosuke Sano; Yasushi Kino; Tsutomu Sekine

doi:10.1140/epjd/e2014-40807-2

EPJ

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2023 Impact factor 1.5

Atomic, Molecular, Optical and Plasma Physics

Topical issue: Electron and Positron Induced Processes. Guest editors: Michael Brunger, Radu Campeanu, Masamitsu Hoshino, Oddur Ingólfsson, Paulo Limão-Vieira, Nigel Mason, Yasuyuki Nagashima and Hajime Tanuma

Eur. Phys. J. D (2014) 68: 156
https://doi.org/10.1140/epjd/e2014-40807-2

Regular Article

Optimisation of the thickness of the moderator for positron annihilation process study in Ar gas^*

Toshitaka Oka¹^,2^a, Yosuke Sano², Yasushi Kino² and Tsutomu Sekine¹

¹ Institute for Excellence in Higher Education, Tohoku University, 980–8576 Sendai, Japan
² Department of Chemistry, Tohoku University, 980–8578 Sendai, Japan

^a e-mail: kotobuki@m.tohoku.ac.jp

Received: 17 December 2013
Received in final form: 3 February 2014
Published online: 23 June 2014

Abstract

To investigate the deceleration and annihilation processes of positron in noble gas, we attempted to optimise the thickness of the positron moderator. The results of the decreasing trend of free positron intensity and ortho-positronium intensity with the thickness, and the annihilation rate suggest that the energy of almost all the positrons passed through the metal foils was much above the positronium formation threshold of 9 eV. Total thickness of 0.1 g cm^-2 of the moderator and the Ar gas was required to stop almost all the positron in Ar gas.

Contribution to the Topical Issue “Electron and Positron Induced Processes”, edited by Michael Brunger, Radu Campeanu, Masamitsu Hoshino, Oddur Ingólfsson, Paulo Limão-Vieira, Nigel Mason, Yasuyuki Nagashima and Hajime Tanuma.

© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2014