Physicists Achieve Breakthrough in Laser Cooling of Positronium: AEgIS Collaboration

Physicists Achieve Breakthrough in Laser Cooling of Positronium: AEgIS Collaboration

An international team of physicists from the Anti-hydrogen Experiment: Gravity, Interferometry, Spectroscopy (AEgIS) collaboration has achieved a groundbreaking feat by demonstrating the laser cooling of Positronium.

What is Positronium?

  • Positronium consists of a bound electron (e-) and positron (e+), making it a fundamental atomic system.
  • It has a very short lifespan, with a half-life of 142 nanoseconds, due to annihilation.
  • With a mass twice that of an electron, it’s a pure leptonic atom.

Significance of Laser Cooling

  • Laser cooling of Positronium offers opportunities for testing fundamental theories in physics.
  • Its halved frequencies for excitation make it suitable for laser cooling experiments.

Collaboration and Announcement

  • Physicists from 19 European and one Indian research group, part of AEgIS, announced this achievement.
  • The experiment took place at CERN, Geneva.

Precursor Experiment

  • This experiment is a crucial step before the formation of anti-Hydrogen and measuring Earth’s gravitational acceleration on antihydrogen in the AEgIS experiment.

Experimental Process

  • Multiple experimental runs were conducted in the CERN accelerator beam hall.
  • The AEgIS experiment setup began in 2008, continuing until 2016.
  • The experiment faced technological challenges but succeeded through innovations.

Results and Expectations

  • Laser cooling reduced Positronium atoms’ temperature from ~380 Kelvin to ~170 Kelvin.
  • The experiment utilized alexandrite-based laser systems in deep ultraviolet or infrared frequency bands.
  • Expectations include spectroscopic comparisons for Quantum Electrodynamics (QED) and potential degenerate gas of Positronium.

Implications and Future Prospects

  • High-precision measurements of properties and gravitational behavior could reveal new physics.
  • Production of a positronium Bose–Einstein condensate holds promise for fundamental and applied research, including coherent gamma-ray light production.

Multiple Choice Questions (MCQs):

  1. What is the composition of Positronium?
    • A) Proton and Electron
    • B) Neutron and Positron
    • C) Electron and Positron
    • D) Neutron and Electron
    • Answer: C) Electron and Positron
  2. What is the half-life of Positronium?
    • A) 142 seconds
    • B) 142 milliseconds
    • C) 142 nanoseconds
    • D) 142 microseconds
    • Answer: C) 142 nanoseconds
  3. Where was the laser cooling of Positronium experiment conducted?
    • A) NASA
    • B) CERN
    • C) ESA
    • D) JAXA
    • Answer: B) CERN
  4. What was the temperature reduction achieved through laser cooling of Positronium?
    • A) From ~380 Kelvin to ~170 Kelvin
    • B) From ~500 Kelvin to ~200 Kelvin
    • C) From ~300 Kelvin to ~100 Kelvin
    • D) From ~200 Kelvin to ~50 Kelvin
    • Answer: A) From ~380 Kelvin to ~170 Kelvin
  5. What is expected from the laser cooling experiment regarding Quantum Electrodynamics (QED)?
    • A) Formation of a Bose–Einstein condensate
    • B) Measurement of gravitational behavior
    • C) Spectroscopic comparisons
    • D) Production of gamma-ray laser
    • Answer: C) Spectroscopic comparisons