POSITRONIUM

Why in News?                                                                                                        

For the first time, an international collaboration of researchers has successfully demonstrated the laser cooling of Positronium, a short-lived hydrogen-like atom that provides an ideal testing ground for bound-state quantum electrodynamics. The Antihydrogen Experiment: Gravity, Interferometry, Spectroscopy (AEgIS) collaboration has performed complex experiments at the European Organization for Nuclear Research (CERN) in order to obtain this breakthrough. The results could pave the way for taking up advanced studies leading to improved understanding of the physical nature, comprising matter and antimatter facilitated through the interactions between light and charged matter.

What is Positronium?

• Positronium is a fundamental atom that comprises an electron (e-) and a positron (e+).

• Electrons and positrons are leptons, and they interact through electromagnetic and weak forces.

• A usual atom is made up of a mixture of baryons and leptons.

• Since Positronium is only made up of electrons and positrons, and no usual nuclear matter, it has the unique distinction of being a purely leptonic atom.

• Sadiq Rangwala, Professor, Light and Matter Group at Raman Research Institute (RRI), an autonomous institute of the Department of Science and Technology (DST) of the Government of India, is part of the AEgIS collaboration that comprises physicists from 19 European groups and one Indian group.

• Even though this field has been under active research since the late 1980s, several technological innovations and manufacturing of cutting-edge lasers finally facilitated the laser cooling of Positronium

• In the recently published paper in the Physical Review Letters, the AEgIS team has described the laser cooling of Positronium atoms achieved from ~380 Kelvin (106.85 degrees Celsius) to ~170 Kelvin (minus 103.15 degrees Celsius), using a 70-nanosecond pulsed alexandrite-based laser system.

• Laser cooling anti-atoms and their spectroscopic comparison is a critical and vital test for the Quantum Electro Dynamics (QED).