A physicist at the University of California, Riverside, has performed calculations showing hollow spherical bubbles filled with a gas of positronium atoms are stable in liquid helium.
Extremely short-lived and only briefly stable, positronium is a hydrogen-like atom and a mixture of matter and antimatter—specifically, bound states of electrons and their antiparticles called positrons. To create a gamma-ray laser beam, positronium needs to be in a state called a Bose-Einstein condensate—a collection of positronium atoms in the same quantum state, allowing for more interactions and gamma radiation. Such a condensate is the key ingredient of a gamma-ray laser.
"My calculations show that a bubble in liquid helium containing a million atoms of positronium would have a number density six times that of ordinary air and would exist as a matter-antimatter Bose-Einstein condensate," said Allen Mills, a professor in the Department of Physics and Astronomy and sole author of the study that appears today in Physical Review A.To read more, click here.