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The confined variational method is applied to investigate the low-energy elastic scattering of ortho-positronium from $\text{H}_2$ by first-principles quantum mechanics. Describing the correlation effect with explicitly correlated…

Atomic Physics · Physics 2019-09-11 J. -Y. Zhang , M. -S. Wu , Y. Qian , X. Gao , Y. -J. Yang , K. Varga , Z. -C. Yan , U. Schwingenschlögl

In this paper, we discuss the dissociative electron attachment process in Ammonia. Kinetic energy and angular distributions of H^{-} and NH_{2}^{-} fragment anions across the two well known resonances at 5.5 eV and 10.5 eV are reported. The…

Chemical Physics · Physics 2010-07-30 N. Bhargava Ram , E. Krishnakumar

We investigate positron annihilation in electron liquid as a case study for many-body theory, in particular the optimized Fermi Hypernetted Chain (FHNC-EL) method. We examine several approximation schemes and show that one has to go up to…

Condensed Matter · Physics 2010-09-24 V. Apaja , S. Denk , E. Krotscheck

Electron anti-neutrinos are commonly detected in liquid scintillator experiments via inverse beta decay, by looking at the coincidence between the reaction products, neutron and positron. Prior to positron annihilation, an electron-positron…

Instrumentation and Detectors · Physics 2011-02-28 D. Franco , G. Consolati , D. Trezzi

We calculate elastic scattering of positronium (Ps) by the Xe atom using the recently developed pseudopotential method [I. I. Fabrikant and G. F. Gribakin, Phys. Rev. A 90, 052717 (2014)] and review general features of Ps scattering from…

Atomic Physics · Physics 2016-03-03 G. F. Gribakin , A. R. Swann , R. S. Wilde , I. I. Fabrikant

Resonances from electron attachment to $\text{NO}_2$ have been identified in the total electron scattering cross sections (TCS) measured with a magnetically confined electron transmission apparatus. The corresponding absolute electron…

Chemical Physics · Physics 2026-05-29 Ana I. Lozano , Francisco Blanco , Juan C. Oller , Paulo Limão-Vieira , Gustavo García

Ortho-positronium (o-Ps) formation and decay can replace the annihilation process, when positron interacts in liquid scintillator media. The delay induced by the positronium decay represents either a potential signature for anti-neutrino…

Instrumentation and Detectors · Physics 2013-12-16 G. Consolati , D. Franco , S. Hans , C. Jollet , A. Meregaglia , S. Perasso , A. Tonazzo , M. Yeh

When recent experimental positronium (Ps) formation cross sections in noble gases have been compared with the most up-to date theoretical studies, the agreement is qualitative, but not quantitative. In this paper we re-examine this process…

Atomic Physics · Physics 2009-11-11 L. J. M. Dunlop , G. F. Gribakin

We report the first observation of the annihilation of positronium from the 2S state. Positronium (Ps) is excited with a two-photon transition from the 1S to the 2S state where its lifetime is increased by a factor of eight compared to the…

We present first-principles approaches based on density functional theory for calculating positron states and annihilation characteristics in condensed matter. The treatment of the electron-positron correlation effects (the enhancement of…

Materials Science · Physics 2007-05-23 B. Barbiellini , M. Hakala , R. M. Nieminen , M. J. Puska

We investigate the elastic and inelastic scattering of positrons by sodium atoms in both the ground state, Na($3s$), and excited states, Na*($3p$, $4s$, $3d$), using the hyperspherical coordinate method with a model potential to represent…

Atomic Physics · Physics 2025-07-16 Ning-Ning Gao , Hui-Li Han , Ting-Yun Shi

We present a new, simplified analysis of the low-energy electron-positron interaction, and use the resulting effective theory to calculate the binding effects that contribute to the decay rate, Gamma, of orthopositronium, through…

High Energy Physics - Phenomenology · Physics 2009-12-30 Richard J. Hill , G. Peter Lepage

Calculations of the relaxation energy, contact pair-correlation function, and annihilating-pair momentum density for a single positron immersed in a homogeneous electron gas are presented. We achieve an accurate description of the…

Mesoscale and Nanoscale Physics · Physics 2011-01-20 N. D. Drummond , P. Lopez Rios , C. J. Pickard , R. J. Needs

We report measurements of resonant low-energy electron attachment to O\(_2\) molecular impurities in neon gas in the temperature range \(46.5\,\mbox{K}\le T\le 101\,\mbox{K}\). The reduced attachment frequency \(\nu_A/N\) shows a well…

Plasma Physics · Physics 2020-04-22 A. F. Borghesani

We report on a direct search for a three-body decay of the orthopositronium into a photon and two penetrating particles, o-Ps -> gamma + X1 + X2. The existence of this decay could explain the discrepancy between the measured and the…

High Energy Physics - Experiment · Physics 2008-11-26 A. Badertscher , P. Crivelli , M. Felcini , S. N. Gninenko , N. A. Goloubev , P. Nedelec , J. P. Peigneux , V. Postoev , A. Rubbia , D. Sillou

Due to the dominant electron capture by positrons from the molecular wall and the spatial dephasing across the wall-width, a powerful diffraction effect universally underlies the positronium (Ps) formation from fullerenes. This results into…

Atomic and Molecular Clusters · Physics 2021-06-08 Paul-Antoine Hervieux , Anzumaan R. Chakraborty , Himadri S. Chakraborty

Following recent theoretical results, it is suggested that positronium (Ps) might undergo spontaneous oscillations between two 4D spacetime sheets whenever subjected to constant irrotational magnetic vector potentials. We show that these…

High Energy Physics - Theory · Physics 2008-11-26 Michael Sarrazin , Fabrice Petit

The positron-electron pair annihilation in two photons is known for its numerous applications using PET scanners. The decay of Positronium (Ps) from a standard sealed source in more than two photons is less likely but can be observed with a…

Physics Education · Physics 2011-09-20 M. E. A. Elbasher , W. Erasmus , E. A. M. Khaleel , J. Ndayishimye , P. Papka

The excess energy emitted during the positronium (Ps) formation in condensed matter may be released as light. Spectroscopic analysis of this light can be a new method of studying the electronic properties of materials. We report the first…

The recent theoretical and experimental activities in positronium (Ps) scattering by atoms and molecules are reviewed with special emphasis at low energies. We critically compare the results of different groups $-$ theoretical and…

Chemical Physics · Physics 2009-11-07 Sadhan K. Adhikari