Abstract
We have measured total ( ) and positronium formation ( ) cross sections for 1–302-eV positrons ( 's) and 's for electrons ( 's) scattered by hydrogen atoms and molecules. A beam transmission technique is used to measure 's where the projectile beam passes through a low-temperature scattering cell containing a mixture of hydrogen atoms and molecules generated in an adjacent radio-frequency discharge region. 's are measured using the same scattering cell by detecting coincidences of 511-keV annihilation γ rays produced by the decay of para-Ps and by the interaction of ortho-Ps with the walls of the scattering cell in which the Ps is formed. The present -H 's and 's agree very well with theoretical calculations. Comparisons of the present and -H 's show a merging to within 20% for energies above 12 eV.
- Received 12 August 1996
DOI:https://doi.org/10.1103/PhysRevA.55.361
©1997 American Physical Society