The production of molecular positronium

  title={The production of molecular positronium},
  author={D. B. Cassidy and Allen P. Mills},
It has been known for many years that an electron and its antiparticle, the positron, may together form a metastable hydrogen-like atom, known as positronium or Ps (ref. 1). In 1946, Wheeler speculated that two Ps atoms may combine to form the di-positronium molecule (Ps2), with a binding energy of 0.4 eV. More recently, this molecule has been studied theoretically; however, because Ps has a short lifetime and it is difficult to obtain low-energy positrons in large numbers, Ps2 has not… 
Optical spectroscopy of atomic and molecular positronium
Positronium (Ps) is a purely leptonic hydrogen-like atom formed from an electron and a positron. Since the interactions of electrons and positrons are thought to be almost entirely electromagnetic,
On the Nature of the Positronic Bond.
It is demonstrated that the positron density enclosed in each atom is capable of stabilizing interactions with the electron density of the neighboring atom, and this electrostatic interaction suffices to make the whole system bonded against all dissociation channels.
Antimatter Atomic Physics
Positronium, the atom formed from an electron and a positron, is a gateway to very cold antihydrogen atoms and possibly a γ-ray laser. Positronium (Ps), the bound state of an electron and its
Possible experiments with high density positronium
  • A. Mills
  • Materials Science
  • 2019
Although it can probably only exist within a confining potential, a positronium (Ps) Bose-Einstein condensate (BEC) would be interesting because it could be viewed as the ultimate member of Wheeler’s
Atomic and molecular structures of positronium, dipositronium and positronium hydride
The structures of the above exotic chemical entities based on exact atomic radii are evaluated here for the first time and are of help for a better understanding and further development of the chemistry and physics of these short lived compounds.
Experiments with Dense Low-Energy Positrons and Positronium
Abstract This chapter reviews the steps required to capture and accumulate copious numbers of low-energy positrons, and to form positronium (Ps) atoms at low energies. We then relate the few results
Positronium – Hydrogen Like and Unlike
A brief review on positronium, Ps, hydrogen-like system built from positron and electron, is outlined from its beginning in 1935, the first theoretical study on this relatively stable
Positronium formation via excitonlike states on Si and Ge surfaces
Recent experiments combining lifetime and laser spectroscopy of positronium (Ps) show that these atoms are emitted from p-Si(100) at a rate that depends on the sample temperature, suggesting a
Two positrons can form a chemical bond in (PsH)2.
This is the first time two positrons are shown to behave like two electrons in ordinary matter, enlarging the definition of what is a chemical bond dating back to Lewis.
Covalent bonds in positron dihalides.
Analysis of the electron and positron densities points out that the formation of positron covalent bonds underlies the stabilization of the otherwise repelling dihalides, revealing that positronic bonding can reach far beyond the previously addressed e+[H-H-] molecule.


Radiation damage in a-SiO2 exposed to intense positron pulses
Abstract In addition to its numerous technological applications amorphous silica (a-SiO2) is also well suited to the creation and study of exotic atoms such as positronium (Ps) and muonium. In
Positronium-surface interaction in the pores of the Vycor glass
The positronium-surface interaction has been studied experimentally and theoretically. The angular correlation of photons from annihilation of positronium on the internal surfaces of porous Vycor
Experiments with a high-density positronium gas.
A high-density gas of interacting positronium atoms is created by irradiating a thin film of nanoporous silica with intense positron bursts and the Ps lifetime is measured using a new single-shot technique to suggest an effective cross section of 2.9 x 10(-14) cm-2.
Physisorption of positronium on quartz surfaces.
A first-principles density-functional calculation of the key parameters determining the interaction potential between Ps and an alpha-quartz surface shows that there is indeed a bound state with an energy of 0.14 eV, a value which agrees very well with the experimental estimate of approximately 0.15 eV.
Spur reaction model of positronium formation
A new model of positronium (Ps) formation is proposed. Positronium is assumed to be formed by a reaction between a positron and an electron in the positron spur. Ps formation must compete with
Annihilation libre de l'ortho-positonium formé dans certaines poudres de grande surface spécifique
2014 The two long mean-lives observed for positron annihilation in some powders (Al2O3, MgO, SiO2) result from ortho-positronium formation. The longest mean-life corresponds to the triplet-state part
Emerging science and technology of antimatter plasmas and trap-based beams
Progress in the ability to accumulate and cool positrons and antiprotons is enabling new scientific and technological opportunities. The driver for this work is plasma physics research—developing new
Possibilities for Bose condensation of positronium.
  • Platzman, Mills
  • Physics, Medicine
    Physical review. B, Condensed matter
  • 1994
The scenario where this dense gas of polarized Ps atoms may cool through a weakly interacting Bose transition is considered, and the rates for thermalization with the wall, equilibrium in the bulk, and loss of polarization by exchange collisions are calculated.
Positron spectroscopy of solids : Varenna on Lake Como, Villa Monastero, 6-16 July 1993
The lifetime of a positron inside a solid is normally less than a fraction of nanosecond. This is a very short time on a human scale, but is long enough to enable the positron to visit an extended
Positronium Decay in Molecular Substances
The overlap of the positron component of the wave function of positronium (Ps) in dense molecular substances with the lattice wave function determines the $2\ensuremath{\gamma}$ annihilation rate of