Context:
Recently, CERN scientists from Anti-hydrogen Experiment: Gravity, Interferometry, Spectroscopy (AEgIS) collaboration carried out laser cooling of Positronium for the 1st time successfully.
Laser Cooling:
- A technique that uses laser light to cool atoms, molecules, and small mechanical systems
- Based on the interaction between light and matter, and how photons transfer momentum to atoms
- Basic Principle – The absorption and re-emission of photons
Positronium (Ps):
- Discovered in 1951
- The lightest known particle system
- Extremely unstable
- Comprising – Only of an electron (e−) and a positron (e+)
- Have a very short lifetime, annihilating into gamma rays in 142 billionths of a second
- Mass – Twice that of an electron
- Pure leptonic atom – A perfect system for physics experiments
- Can be cooled enough to measure it with high precision due to two point-like particles, the electron and its antimatter
- They interact through electromagnetic and weak forces
AEgIS:
- One of several experiments at CERN’s Antimatter Factory
- Goal – Direct measurement of Earth’s gravitational acceleration (g) on antihydrogen
- Collaboration – Physicists from Europe and from India
Matter – Antimatter:
- Antimatter – A substance made up of antiparticles, which are the opposite of the particles that make up ordinary matter
- Anti-particles – A subatomic particle that has the same mass as its corresponding particle, but with the opposite electric charge and magnetic moment
- Can combine to form anti-atoms and, in principle, could even form anti-matter regions.
- Forms of matter – Solids, liquids, gases, and plasmas
- Consisting of subatomic particles that give them mass and volume
- Sub-atomic particles –
- Protons and neutrons (also known as baryons), electrons and neutrinos (also known as leptons), and other particles.
Leptons or Leptonic atom:
- Elementary particles – They do not appear to be made up of smaller units of matter
- Can either carry 1 unit of electric charge or be neutral
- Charged leptons – Electrons, muons, and taus
- Each of these types has a negative charge and a distinct mass
European Council for Nuclear Research (CERN):
- Founded in – 1954
- Location – Geneva (Franco-Swiss border)
- Aim – To uncover what the universe is made of and how it works
- Member States – 23 states
- India – An Associate Member
Source: The Hindu
Previous Year Question
What is the purpose of ‘evolved Laser Interferometer Space Antenna (eLISA)’ project?
[UPSC Civil Services Exam – 2017 Prelims]
(a) To detect neutrinos
(b) To detect gravitational waves
(c) To detect the effectiveness of missile defence system
(d) To study the effect of solar flares on our communication systems
Answer: (b)
