Session FTP1: Poster Session I (19:00-21:30)
7:00 PM–7:00 PM, Tuesday, October 14, 2008
Room: Salon F-J
Chair: I. Langmuir
Abstract ID: BAPS.2008.GEC.FTP1.94
Abstract: FTP1.00094 : High Resolution Studies of Low Energy Positron Collisions with Helium
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Abstract 
Authors:
Stephen Buckman
James Sullivan
Peter Caradonna
Adric Jones
Casten Makochekanwa
Daniel Slaughter
(Australian National University)
Mark Stevenson
Birgit Lohmann
(University of Adelaide)
A high resolution, trap-based beam of positrons has been used to study total scattering, positronium formation and direct ionization of He atoms. The energy resolution of the positron beam is typically 65 meV, and measurements have been carried out at incident positron energies between 1 and 60 eV. The experimental arrangement consists of a pulsed beam of positrons from a Surko trap combined with a gas cell containing the helium target gas and a retarding potential analyzer (RPA). ~The beam is confined radially using a 500 gauss magnetic field and the RPA allows absolute cross sections to be obtained by measuring the scattering rate for each process. Normalisation depends only on a measurement of the target gas pressure (in the milliTorr range) and ~the length of the scattering cell. Results will be compared with previous measurements and contemporary theory.
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2008.GEC.FTP1.94