Yin and yang: When an electron comes into contact with it's corresponding and opposite antimatter particle, the positron, they create a short-lived, hydrogen-like atom called positronium, before annihilating one another. Now physicists have succeeded in combining these atoms to fleetingly form molecules of positronium.
Credit: Wikipedia
PARIS: U.S. physicists have met a 60-year challenge to create molecules of positronium, a short-lived atom that comprises matter and antimatter.
The achievement may help the development of fusion power as well as directed-energy weapons such as gamma-ray lasers. Experts also hope that it will also spur explanations for a long-standing enigma about the universe.
Particle-antiparticle pairs
Under the standard laws of physics, for every type of ordinary-matter particle, a corresponding "antiparticle" exists. For instance, the positively-charged proton has a negatively-charged counterpart, the antiproton. The electron, which is negatively charged, is offset by the postively-charged positron.
When particles and antiparticles come together, the meeting is only very brief, for they annihilate each other in a flash of energy. In the case of electrons and positrons, the two species of particle create a short-lived, hydrogen-like atom called positronium, whose existence was first mooted in 1946 and confirmed five years later.
The theoretician behind positronium, American physicist John Wheeler, also suggested that positronium should exist as a two-atom molecule, called Ps2, and that there should even be a three-atom version, Ps3.
Until now, this hypothesis has never been confirmed, the big problem being the task of creating such finicky, fleeting molecules in lab conditions.
In free space, two atoms of positronium cannot combine together, because they have such excess energy that they simply fly apart again. Writing in the British journal Nature today, University of California Riverside physicists David Cassidy and Allen Mills describe how they overcame this obstacle to forge the world's first Ps2 in laboratory conditions.
They did it by first creating a special trap that confined some 20 million positrons, which were then focussed in a nano-second blast onto the surface of porous silica.
Positron trap
Holed up within the pores, the positrons captured electrons to form atoms of positronium, which in turn linked up to form around 100,000 two-atom molecules before annilation.
The silica walls of the pores were the key to the success, as they absorbed the excess energy of the atoms, allowing them to wed, albeit fleetingly. Evidence that the long-sought molecules had been created, comes from a tell-tale temperature curve of gamma rays released by the annihilation.
Matter-antimatter annihilation has outlets in medicine, where the Positron Emission Tomography (PET) scan provides a three-dimensional image of the body to help doctors detect diseases.
Physicists have long pondered over an enigma that challenges the "symmetrical" law by which matter is balanced by antimatter. Matter appears to dominate in the visible universe, and the new research could help explain why this is, other experts said.
"Their research is giving us new ways to understand matter and antimatter," commented Clifford Surko, a professor of physics at the University of California San Diego, who was not involved in the study. "It also provides novel techniques to create even larger collections of antimatter that will likely lead to new science and, potentially, to important new technologies."
Positronium
I wonder if those silica walls could be termed... positronic branes.
(boom boom)
confinement
now if the hybrid locked in the silica wafer could be confined and maintained before anilliation....?