ANtarctic Impulsive Transient Antenna

  • In a significant breakthrough, a team of researchers have succeeded in finding "a fountain of high-energy particles erupting from the ice" in Antarctica which according to the researchers could be proof of a parallel universe.
  • ANtarctic Impulsive Transient Antenna or ANITA - an experiment maintained by researchers at NASA - has suddenly come into the limelight as the cosmic-ray shower that is key to the new discovery was a part of NASA's ANITA and Ice Cube experiment taking place in Antarctica.

What is ANITA?

  • Designed by world's premier space agency NASA, the ANITA instrument is a radio telescope which is used to detect ultra-high energy cosmic-ray neutrinos from a scientific balloon flying over Antarctica.
  • It is the first NASA observatory for neutrinos of any kind.
  • It involves an array of radio antennas attached to a helium balloon which flies over the Antarctic ice sheet at 37,000 meters.
  • To get a gauge of exactly how high is that, know that commercial flights fly almost a fourth of that height.
  • The height is important here to shut out all other "noises" so that the ANITA antennas can "listen" to the cosmos and detect high-energy particles, known as neutrinos, which constantly bombard the planet.
  • ANITA succeeded in detecting the 'fountain' of high-energy particles in 2006 and 2014 but the researchers initially thought them as background noise or glitches.
Different ways signals can reach ANITA as the device floats over Antarctica hanging from its balloon

How does ANITA detect Neutrinos?

  • The ANITA instrument <detects these ultra-high energy neutrinos by use of the Askaryan effect.
  • This effect predicts the production of a coherent radio emission from the cascade of particles produced in a high-energy particle interaction.
  • In order to detect this radio emission (Askaryan pulses) we need a radio transparent medium for the interaction to occur in - and lots of it since these interactions is rare.

Experimental Time Frame

  • ANITA-I launched from McMurdo, Antarctica in the summer of 2006–07.
  • ANITA-II, a modified instrument with 40 antennas, launched from McMurdo Station in the summer of 2008–2009.
  • ANITA-III, launched in December 2014.
  • ANITA-IV launched in December 2016, with a lighter overall build, tunable notch filters and an improved trigger system.

Neutrinos

  • A neutrino is a subatomic particle that is very similar to an electron, but has no electrical charge and a very small mass, which might even be zero.
  • Neutrinos are one of the most abundant particles in the universe.
  • These are affected only by a "weak" sub-atomic force of much shorter range than electromagnetism, and are therefore able to pass through great distances in matter without being affected by it.
  • Natural sources of neutrinos include the radioactive decay of primordial elements within the earth, which generate a large flux of low-energy electron-anti-neutrinos. 

Askaryan Effect

  • It is the phenomenon whereby a particle traveling faster than the phase velocity of light in a dense dielectric (such as salt, ice or the lunar regolith) produces a shower of secondary charged particles which contain a charge anisotropy and thus emits a cone of coherent radiation in the radio or microwave part of the electromagnetic spectrum.
  • It is similar to the Cherenkov radiation.
  • It is named after Gurgen Askaryan, a Soviet-Armenian physicist who postulated it in 1962.



स्रोत : Civil Services Chronicle Online, May, 2020