Positronium formation in positron-hydrogen scattering

Hewitt, R N; Noble, C. J.; Bransden, B H

doi:10.1088/0953-4075/23/22/019

Cited by 72 publications

(34 citation statements)

References 25 publications

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“…However, these calculations did not allow for positronium formation and it is doubtful whether these calculations are accurate in the energy region where the positronium formation cross section is the largest cross section. Just recently, there have been some calculations that have explicitly allowed for the coupling between the hydrogen and positronium states (Hewitt et al 1990;Mitroy andStelbovics 1994b, 1994c;McAlinden et al 1994;Sarkar and Ghosh 1994), however, for the most part the size of the channel space has been relatively small. One of the features of these calculations was the presence of numerous resonances above the ionisation threshold (Higgins and Burke 1991;Kernoghan et al 1994;Mitroy and Stelbovics 1994a).…”

Section: Introductionmentioning

confidence: 99%

Positron - Hydrogen Scattering at Intermediate Energies

Mitroy¹

1996

Aust. J. Phys.

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Calculations of positron-hydrogen scattering at intermediate energies up to a maximum energy of 10 Ryd are performed using the close coupling (CC) approach. A large L2 basis of positron-hydrogen channels (28 states) is supplemented by the Ps(1s), Ps(2s) and Ps(2p) channels. The inclusion of the positronium states in the CC expansion leads to a model which can describe most of the physics of the positron-hydrogen system with a reasonable degree of accuracy. In particular, the positronium formation cross section, the total reaction cross section and the ionisation cross section are all in agreement with experiment. The elastic scattering cross section and the cross sections for positron impact excitation of the H(2s) and H(2p) levels are also reported.

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Section: Introductionmentioning

confidence: 99%

Positron - Hydrogen Scattering at Intermediate Energies

Mitroy¹

1996

Aust. J. Phys.

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“…In 1990, Hewitt et al (1990) attempted the first realistic coupled-channels calculations with explicit coupling to the positronium channels in the intermediate energy region. More recently, there have been some 18-state R-matrix calculations (McAlinden et al 1994, Kernoghan et al 1995 that have provided a set of cross sections for both the low and intermediate energy regions.…”

Section: Introductionmentioning

confidence: 99%

Positron - hydrogen and positronium - proton scattering at intermediate and high energies

Ratnavelu

Mitroy

Stelbovics

1996

J. Phys. B: At. Mol. Opt. Phys.

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Abstract. Positron scattering from atomic hydrogen is studied at energies ranging from 4 to 100 Ryd using the close-coupling approach and cross sections from both the e + -H and Psp entrance channels are reported in a basis comprising 1s, 2s and 2p states of the hydrogen and positronium atoms. Comparative studies with widely used approximation methods such as the first Born, unitarized Born and second Born approximations are presented. With the exception of elastic scattering for the Ps(1s)-p entrance channel, it was found that on-shell approximations such as the first Born and the unitarized Born approximations are reasonably accurate for collisions not involving particle transfer provided the energy is sufficiently high. Rearrangement collisions on the other hand are dominated by off-the-energy-shell scattering and the accurate approximation at high energies is the second Born approximation. Further, the effects of positronium channels on the direct reactions are investigated and we conclude that the positronium formation channels can be omitted for energies greater than 20 Ryd. Elastic scattering in the Ps(1s)-p entrance channel is seen to be unique, the high-energy behaviour of the phase shifts is different from any other quantum system.

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“…Because of this, the positron-hydrogen and positronium-proton collision systems form one of the simplest possible scattering systems in which a genuine rearrangement collision is possible. While there have recently been a number of calculations of positron-hydrogen scattering (Archer et ale 1990;Hewitt et ale 1990;Higgins and Burke 1993;McAlinden et ale 1994;Mitroy andStelbovics 1994a, 1994b;Mitroy and Ratnavelu 1995;Roy and Mandal 1993;Zhou et ale 1994), the same cannot be said for positronium-proton scattering. This is despite the fact that the behaviour of the positronium-proton elastic phase shift is quite unusual at high energies (Mitroy et ale 1995), and the positronium-antiproton to electron-antihydrogen reaction has been promoted as one of the most efficient ways to form antihydrogen (Charlton et ale 1994;Deutch et ale 1988Deutch et ale , 1993).…”

Section: Introductionmentioning

confidence: 99%

Positronium-Proton Scattering at Low Energies

Mitroy¹

1995

Aust. J. Phys.

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Calculations of low energy positronium-proton scattering using the close coupling approach are reported at energies below the three-body breakup energy of 0·5 Rydberg. The channel space includes nine physical hydrogen and positronium states and in addition twelve hydrogen and positronium pseudo-states. Total elastic and electron-transfer cross sections are reported at incident energies below the ionisation threshold. Cross sections for electron transfer to the H(n=2) and H(n=3) levels are also reported.

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Positronium formation in positron-hydrogen scattering

Cited by 72 publications

References 25 publications

Positron - Hydrogen Scattering at Intermediate Energies

Positron - Hydrogen Scattering at Intermediate Energies

Positron - hydrogen and positronium - proton scattering at intermediate and high energies

Positronium-Proton Scattering at Low Energies

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