GS Paper III
News Excerpt:
Recently, an international team of physicists from the Anti-hydrogen Experiment: Gravity, Interferometry, Spectroscopy (AEgIS) collaboration has achieved a breakthrough by demonstrating the laser cooling of Positronium.
What is Positron:
- Positronium, comprising a bound electron ( e-) and positron ( e+), is a fundamental atomic system.
- Due to its very short life, it annihilates with a half life of 142 nano-seconds.
- Its mass is twice the electron mass and enjoys the unique distinction of being a pure leptonic atom.
Leptons:
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- This hydrogen-like system, with halved frequencies for excitation, makes it a great contender for attempting laser cooling and thereby performing tests of fundamental theories in physics.
About the Experiment:
- The experiment was conducted by 19 European and one Indian research group comprising the Antihydrogen Experiment: Gravity, Interferometry, Spectroscopy (AEgIS) collaboration.
- The experiment was performed at the European Organization for Nuclear Research, more popularly known as CERN, in Geneva.
- This is an important precursor experiment to the formation of anti-Hydrogen and the measurement of Earth’s gravitational acceleration on antihydrogen in the AEgIS experiment.
- In addition, this scientific feat could open prospects to produce a gamma-ray laser that would eventually allow researchers to look inside the atomic nucleus and have applications beyond physics.
- This scientific achievement could open prospects to produce a gamma-ray laser that would eventually allow researchers to look inside the atomic nucleus and have applications beyond physics.
About the successfully conducted AEgIS experiment:
- During the past few years, several rounds of experimental runs were performed in an accelerator beam hall of the CERN before the AEgIS team tasted success.
- It was formally accepted as a scientific experiment by CERN in 2008, the setting up of the AEgIS experiment, its construction and commissioning continued through 2012 – 2016.
- AEgIS comprised designing of the complex particle traps used to confine antiparticles, antiprotons and positrons.
- In 2018, AEgIS became the first in the world to demonstrate the pulsed production of antihydrogen atoms.
- Experimentalists achieved laser cooling of Positronium atoms initially from ~380 Kelvin to ~170 Kelvin, and demonstrated the cooling in one dimension using a 70-nanosecond pulse of the alexandrite-based laser system.
- The lasers deployed were either in the deep ultraviolet or in the infrared frequency bands.
Significance of the experiment:
- This experiment is expected to pave the way for performing spectroscopic comparisons required for Quantum Electrodynamics (QED).
- Quantum Electrodynamics (QED): It is a study of the light and its interaction with charged matter, and a possible degenerate gas of Positronium down the road.
- According to CERN, the new scientific development will allow high-precision measurements of the properties and gravitational behaviour of this exotic but simple matter–antimatter system, which could reveal newer physics.
- It also allows the production of a positronium Bose–Einstein condensate, in which all constituents occupy the same quantum state.
- A Bose-Einstein condensate of antimatter would be an incredible tool for both fundamental and applied research, especially if it allowed the production of coherent gamma-ray light with which researchers could peer into the atomic nucleus.
- Such a condensate has been proposed as a candidate to produce coherent gamma-ray light via the matter-antimatter annihilation of its constituents; it would be a laser-like light made up of monochromatic waves that have a constant phase difference between them.
Conclusion:
The successful laser cooling of Positronium by the AEgIS collaboration marks a significant advancement in fundamental physics. This breakthrough not only opens the door to high-precision measurements in Quantum Electrodynamics but also paves the way for producing a positronium Bose-Einstein condensate, offering a powerful tool for both fundamental and applied research.