APS » PROLA » Phys. Rev. A » Volume 67 » Issue 5
< Previous article | Next article >

Phys. Rev. A 67, 052712 (2003) [4 pages]

Enhancement of direct positron annihilation due to temporal capture by an atom

Download: PDF (66 kB) or Buy this Article (Use Article Pack) Export: BibTeX or EndNote (RIS)

Nobuhiro Yamanaka *
RIKEN (Institute of Physical and Chemical Research), Wako, Saitama 351-0198, Japan

Yasushi Kino †, Yasushi Takano, and Hiroshi Kudo
Department of Chemistry, Tohoku University, Sendai 980-8578, Japan

Atsushi Ichimura
Institute of Space and Astronautical Science, Sagamihara, Kanagawa 229-8510, Japan

Received 14 December 2002; published 30 May 2003

We investigate direct positron annihilation during a collision in a gas; this is physically separable from indirect annihilation, i.e., via formation of positronium (Ps) and its decay. The cross section of direct annihilation is calculated from the evolution of a wave packet with a time width much shorter than the Ps lifetime, where the direct contribution is extracted through the time dependence of the survival probability. The cross section obtained for a hydrogen atom is found to be enhanced in energies around 10 eV well above the Ps formation threshold. This enhancement is shown to be due to temporal positron capture with electronic excitation in the atom.


©2003 The American Physical Society

URL: http://link.aps.org/doi/10.1103/PhysRevA.67.052712
DOI: 10.1103/PhysRevA.67.052712
PACS: 34.85.+x, 78.70.Bj, 71.60.+z, 36.10.Dr

* Electronic address: yam@postman.riken.go.jp
† Electronic address: kino@mail.cc.tohoku.ac.jp

[ Abstract  |  Previous article  |  Next article  |  Issue 5 ]