Continuum effects on positron scattering of atomic hydrogen at intermediate energies

Abstract

An optical potential method to study the positron-hydrogen atom scattering system within the close-coupling framework that includes both the positron-hydrogen and positroniumproton channels has been implemented. Ionization, positronium formation and total cross sections are reported and are compared to other available theoretical and experimental data.

Rydberg transitions for positron–hydrogen collisions: asymptotic cross section and scaling law

“…this table we notice that transitions to p-states dominate over transitions to all other states. The fact that the cross section for the 1s − 2p transition is larger than the cross section for the 1s − 2s transition has also been found in earlier investigations [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27]. The enhancement of the total cross section is exhibited not only in the 1s − np transitions, but for any 'optically allowed' (dipole) transitions in which a change of the orbital angular momentum quantum number of the target hydrogen atom satisfies the selection rule | l| = 1.…”

“…This prevented the earlier workers from attempting the study of such problems until recently. Results for positron-hydrogen inelastic scattering are mostly reported for 1s → 2s and 1s → 2p transitions [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27], except a few [28][29][30][31][32]. Recently, Ghoshal and Mandal [30] and Nayek and Ghsohal [31] investigated ns → n s transitions of the hydrogen atom by positron impact.…”

Recommended Positron Scattering Cross Sections for Atomic Systems

“…In the late 1990s, Ratnavelu and Rajagopal [74] demonstrated an optical potential method (CCO(m,n)), within the CC two-centre formalism of Mitroy [37], that allowed for the continuum optical potentials in the positron-atom channels. Using a small basis calculation (CC (3,3) and CCO(3,3)), they reported ionization cross sections, Ps formation cross sections and total cross sections that were in good qualitative and reasonable quantitative agreement with the 31-state CC calculations of Mitroy [75] and the 33-state R-matrix calculations of Kernoghan et.…”