Journal of Physics Conference Series

Detecting Positron-Atom Bound States through Resonant Annihilation and Scattering

V. V. Flambaum, V. A. Dzuba, G. F. Gribakin, C. Harabati

Published Sep 7, 2015• 0 citations

Abstract

A method is proposed for detecting positron-atom bound states by observing enhanced positron annihilation due to electronic Feshbach resonances. Relativistic coupled-cluster single-double approximation with third-order corrections is used to calculate positron binding energies and resonances for all atoms in Periodic Table.

DOI: 10.1088/1742-6596/635/5/052027

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Journal of Physics Conference Series

Detecting Positron-Atom Bound States through Resonant Annihilation and Scattering

V. V. Flambaum, V. A. Dzuba, G. F. Gribakin, C. Harabati

Published Sep 7, 2015• 0 citations

Publisher

Abstract

DOI: 10.1088/1742-6596/635/5/052027

Related papers

Detecting Positron-Atom Bound States through Resonant Annihilation

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arXiv:1007.4033Physical Review LettersNov 9, 201037 citations

Dipole Enhancement of Positron Binding to Molecules

James R. Danielson, J. J. Gosselin, Clifford M. Surko

Physical Review LettersJun 9, 201089 citations

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Measurements of positron-on-molecule annihilation have established that positrons bind to a variety of molecules via vibrational Feshbach resonances. Data for deeply bound states in benzene and 1-chlorohexane and for positronically excited (i.e., second) bound states in alkanes are used to establish the dependence of annihilation rates on the binding energy and incident positron energy. With this dependence removed, annihilation rates for a broad class of molecules lie on a universal curve as a function of the number of molecular vibrational degrees of freedom. The implications of these results for theoretical models are discussed.Measurements of positron-on-molecule annihilation have established that positrons bind to a variety of molecules via vibrational Feshbach resonances. Data for deeply bound states in benzene and 1-chlorohexane and for positronically excited (i.e., second) bound states in alkanes are used to establish the dependence of annihilation rates on the binding energy and incident positron energy. With this dependence removed, annihilation rates for a broad class of molecules lie on a universal curve as a function of the number of molecular vibrational degrees of freedom. The implications of these results for theoretical models are discussed.

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The very large annihilation rates observed at room temperature in positron collisions with certain molecules have instigated the development of several models of positron annihilation based on the role of virtual processes, Feshbach resonances and bound states. One of the outcomes of these models has been the interest they have generated in investigations of the energy dependence of the annihilation cross-section in the vicinity of inelastic thresholds. The aim of this article is to provide a review of these recent studies and to highlight outstanding questions.The very large annihilation rates observed at room temperature in positron collisions with certain molecules have instigated the development of several models of positron annihilation based on the role of virtual processes, Feshbach resonances and bound states. One of the outcomes of these models has been the interest they have generated in investigations of the energy dependence of the annihilation cross-section in the vicinity of inelastic thresholds. The aim of this article is to provide a review of these recent studies and to highlight outstanding questions.

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Jul 1, 20051 citation

1s

electron in H,

{\mathrm{He}}^{+}

, He,

{\mathrm{Li}}^{2+}

, and

{\mathrm{Li}}^{+}

. The enhancement factor for a free positron annihilating with

{\mathrm{He}}^{+}

and He is found to be close to that of ortho-positronium (i.e., Ps in its triplet state) annihilating with these atoms. The enhancement factor for Ps-He scattering is used in conjunction with the known annihilation rate for pickoff annihilation to derive a scattering length of

1.47{a}_{0}

for Ps-He scattering. Further, enhancement factors for

{e}^{+}

-Ne and

{e}^{+}

-Ar annihilation are used in conjunction with the pickoff annihilation rate to estimate scattering lengths of

1.46{a}_{0}

for Ps-Ne scattering and

1.75{a}_{0}

for Ps-Ar scattering.