TY - JOUR
T1 - Positronium scattering from closed-shell atoms and ions
AU - Mitroy, James
AU - Ivanov, Igor A.
PY - 2002
Y1 - 2002
N2 - The scattering of orthopositronium from He, Ne, Ar, Li+, Na+, and K+ is investigated with the fixed-core stochastic variational method. The scattering length for Ps-He scattering was 1.57a(0), a value consistent with the threshold cross sections derived from three positron lifetime experiments. The scattering lengths for the Ps-Ne and Ps-Ar systems were 1.55a(0) and 1.79a(0), respectively. That there was only a 15% variation among the scattering lengths is compatible with the experiment of Coleman et al. [J. Phys. B 27, 981 (1994)], who found the low-energy cross sections for He, Ne, and Ar to be about the same size. The scattering lengths for Ps scattering from Li+, Na+, and K+ were 12.9a(0), 28.5a(0), and -1.9a(0). The relatively small magnitude of the Ps-K+ scattering length strongly supports previous suggestions that the Ps-K+ system does not support a bound state. The annihilation parameter (1)Z(eff) has also been computed as part of the analysis. The present values of (1)Z(eff) are about 2.5-3 times smaller than the accepted experimental values since short-range electron-positron correlations were not taken into consideration when the annihilation matrix element was evaluated.
AB - The scattering of orthopositronium from He, Ne, Ar, Li+, Na+, and K+ is investigated with the fixed-core stochastic variational method. The scattering length for Ps-He scattering was 1.57a(0), a value consistent with the threshold cross sections derived from three positron lifetime experiments. The scattering lengths for the Ps-Ne and Ps-Ar systems were 1.55a(0) and 1.79a(0), respectively. That there was only a 15% variation among the scattering lengths is compatible with the experiment of Coleman et al. [J. Phys. B 27, 981 (1994)], who found the low-energy cross sections for He, Ne, and Ar to be about the same size. The scattering lengths for Ps scattering from Li+, Na+, and K+ were 12.9a(0), 28.5a(0), and -1.9a(0). The relatively small magnitude of the Ps-K+ scattering length strongly supports previous suggestions that the Ps-K+ system does not support a bound state. The annihilation parameter (1)Z(eff) has also been computed as part of the analysis. The present values of (1)Z(eff) are about 2.5-3 times smaller than the accepted experimental values since short-range electron-positron correlations were not taken into consideration when the annihilation matrix element was evaluated.
KW - transfer cross-section
KW - stochastic variational method
KW - temperature rare-gases
KW - few-body problems
KW - drift velocities
KW - elastic-scattering
KW - low energies
KW - argon atoms
KW - neon atoms
KW - helium
U2 - 10.1103/PhysRevA.65.012509
DO - 10.1103/PhysRevA.65.012509
M3 - Comment/debate
SN - 1094-1622
VL - 65
SP - 012509-1-012509-12
JO - Physical Review A (Atomic, Molecular and Optical Physics)
JF - Physical Review A (Atomic, Molecular and Optical Physics)
IS - 1
ER -