World’s largest Cherenkov telescope opens

  • #1
edguy99
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  • #2
Chronos
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It's a ground based gamma ray telescope useful for studying objects that emit high energy gamma rays, as well as cosmic rays. High energy gamma rays photons are converted to particles [electron/positron pairs] when they strike earth's atmosphere. Cherenkov radiation is then emitted because these particles have velocities that exceed the speed of light in air. Cosmic rays are already particles so they skip the conversion to matter stage.
 
  • #4
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What was the reason for building it in Namibia?
 
  • #5
cepheid
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What was the reason for building it in Namibia?
Good question...this is all I found in the time I spent searching. From here:

http://www.mpi-hd.mpg.de/hfm/HESS/pages/about/

H.E.S.S. is located in Namibia, near the Gamsberg mountain, an area well known for its excellent optical quality
They don't really elaborate, and Wikipedia says exactly the same thing. I suppose you want the Cerenkov radiation to reach the ground without being absorbed. I wonder if it being arid also helps.
 
  • #6
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What was the reason for building it in Namibia?
First and foremost, it is a matter of avoiding light pollution, having clear skies, and having as little atmosphere above the telescope as possible. Thus, you want to build it in a remote, dry, high site. There are of course higher sites than this (1800 metres). I guess that they wanted it to be in the southern hemisphere (considering that a similar set of telescopes, MAGIC, exist at the Canary Islands). Perhaps political reasons played in - Namibia is a politically stable country, and used to be a German colony. I guess that other possible locations would have been Chile and Australia.
 
  • #7
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Gamma-ray are very high energy photons in energy range from few MeV to PeV (10^6 eV to 10^15eV) and even more. The visible photon which enable us to see object around us is just 1-3 eV. And you know the UV(ultra-violet) which in the energy region of 3 eV to 124 eV and most of these are absorbed by Earth atmosphere still we avoid to go out in sunny day due to skin burning by these UV. So u can imagine the energy associated with these gamma-rays.
We can not see all far objects (in space) with optical telescopes and for looking them we need eyes which can look in high energies and gamma-ray telescopes are the eyes for human for looking these far-objects.
The atmosphere absorb gamma-rays also and protect us but in same time it is difficult to observe them from Earth. But their secondaries particles are alternative to observe these high energy gamma-rays from the Earth. There are many telescope around world observing these high energy gamma's like TACTIC (http://pcsati.com/apsd), MAGIC, HESS,.... and more are coming like CTA and MACE (highest gamma-ray observatory).

I hope you may have understand the basic motive of these huge investments.
 

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