Journal ArticleDOI
Feshbach resonances in positron scattering from sodium
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TLDR
In this paper, the effects of channel-coupling scheme, target continuum and positronium (Ps) formation channels on the resonance energy and resonance width are discussed and the Wigner cusp structures at the inelastic channel-opening thresholds in positron-sodium scattering cross sections are also found.Abstract:
S-, P- and D-wave Feshbach resonances in positron-sodium scattering have been investigated by using the momentum space coupled-channels optical method. The target continuum and positronium (Ps) formation channels are included via an optical potential. Feshbach resonances below the target excitation and Ps (n = 2) formation thresholds are predicted and the effects of channel-coupling scheme, target continuum and Ps formation channels on the resonance energy and resonance width are discussed. We have also found the Wigner cusp structures at the inelastic channel-opening thresholds in positron-sodium scattering cross sections.read more
Citations
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Journal ArticleDOI
Resonances in positron-potassium ($e^{+}$-K) system with natural and unnatural parities
Muhammad Umair,Svante Jonsell +1 more
TL;DR: An investigation of resonances with natural and unnatural parities in the positron-potassium system using the complex scaling method and a model potential is used to represent the interactivity.
Journal ArticleDOI
Calculation of resonance states of positronic lithium atom
Takuma Yamashita,Yasushi Kino +1 more
TL;DR: In this paper, the Feshbach resonance states of the positronic lithium atom were precisely calculated with a Gaussian expansion method using a dipole series of resonances supported by ion-dipole interaction.
Journal ArticleDOI
Bound and resonance states of positronic copper atoms
TL;DR: In this paper, a Gaussian expansion method is adopted to directly describe the correlation between the positron and electron, as well as the strong repulsive interaction with the nucleus, and the positions of the resonance for the e$+$Cu dipole series deviate equally from those of e$^+$K.
Journal ArticleDOI
Positronium-dipole induced resonances in e +-H and e +-alkali systems
Muhammad Umair,Svante Jonsell +1 more
TL;DR: In this paper, a dipole series of resonances has been found under positronium n = 2 threshold, for natural parity and n = 3 threshold for unnatural parity states, and these resonances were found to agree well with an analytically derived scaling law.
Journal ArticleDOI
S-wave resonances below the Ps(n=2 ) threshold in positronic sodium interacting with screened Coulomb potentials
TL;DR: In this article, S-wave resonance states of the positronic sodium atom interacting with screened Coulomb potentials (SCP) are studied, and two different SCPs are tested, namely, static SCP and exponential cosine SCP.
References
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Journal ArticleDOI
On the Behavior of Cross Sections Near Thresholds
TL;DR: In this paper, the energy dependence of the cross section for the formation of a product, near the threshold energy for that formation, is considered, and it is shown that the cross-section is, apart from a constant, in the neighborhood of the threshold the same function of energy, no matter what the reaction mechanism is, as long as the long-range interaction of the product particles is the same.
Journal ArticleDOI
Positron and positronium binding to atoms
TL;DR: This work has identified a number of positron-binding systems that decay by electron-positron annihilation with the annihilation rate for e+A systems largely determined by the parent atom ionization potential.
Journal ArticleDOI
Momentum-space coupled-channels optical method for electron-atom scattering
TL;DR: In this paper, a new method for the solution of the problem of electron scattering by a one-electron atom or ion was proposed, which treated all relevant effects explicitly and treated reaction channels under consideration by the coupled-channels method in momentum space.
Journal ArticleDOI
The scattering of electrons by sodium atoms
D. L. Moores,David W. Norcross +1 more
TL;DR: In this article, four state exchange (3s-3p-4 s-3d) close coupling equations are solved for the scattering of electrons by sodium atoms at incident energies up to 5 eV. The results are presented in such a form that a number of different measurable quantities may be readily extracted from tables and simple formulae.
Journal ArticleDOI
Close-coupling approach to positron scattering for lithium, sodium and potassium
TL;DR: In this article, five-state close-coupling calculations are presented for e+-Li (2s-2p-3s-3p 3d 3d), e +-Na (3s 3p-4s 3d-4p-5s3d-5p) and e + -K (4s 4p, 5s 3D-5k 5p 5p) scattering in the energy range 0.5-50 eV.