The first absolute experimental determinations of the differential cross sections for the formation of ground-state positronium are presented for He, Ar, , and near 0°. Results are compared with available theories. The ratio of the differential and integrated cross sections for the targets exposes the higher propensity for forward emission of positronium formed from He and .
DOI:https://doi.org/10.1103/PhysRevLett.115.033401
© 2015 American Physical Society
The Ps beam production efficiency (bullet) of at a Ps energy of 20 eV. The corresponding prediction (triangle) using the weighted mean of (from the data in Fig. 2) is also shown.
Reuse & PermissionsExample of the absolute differential cross section for Ps formation near zero degrees obtained using Eq. (5): the target is and the positron incident energy is 27 eV. Mean (long dash); standard deviations from the mean (short dash).
Reuse & PermissionsThe experimental absolute differential formation cross section for positron scattering from atoms compared with theoretical results: (bullet) this work. He: (diamond) FBA [16]; (square) DWA [16]; (dotted line) close-coupling [19]; (dash dot) eikonal approximation [21]; (double dash) DWA [25]; (solid line) second order DWA [26]; (triangle) 27-state coupled-pseudostate approach [29, 58]; (thick line near the threshold), Kohn variational method [59]. Ar: (triangle) truncated coupled static [24].
Reuse & PermissionsExperimental absolute differential cross sections for Ps formation from and (bullet). Two theories are also shown for : (hollow circle) FBA [18]; (square) second-order Born approximation [17].
Reuse & PermissionsA comparison of the ratio for the atoms and molecules investigated in this work. (a): (bullet) He; (diamond) Ar. Also shown in (a) are for the He theories shown in Fig. 3: (dash double dot) FBA [16]; (dash dot) DWA [16]; (dotted line) close-coupling [19, 65]; (double dash) DWA [25]; (solid line) second order DWA [26]; (dash) eikonal approximation [21]; (triangle) 27-state coupled pseudostate [29, 58]; (thick line near the threshold), Kohn variational method [59]. (b): (square) ; (bullet) .
Reuse & Permissions
