Credit: IceCube Team
Deep below the surface of Antarctica, under the ancient, clear, pure dark ice
more than 1400 meters down, is a strange place to do astronomy. But if you're
hunting the elusive neutrino, it's one of the best sites on earth. Neutrinos,
particles", are difficult to detect since they so rarely interact with
matter, but an ambitious experiment called IceCube is trying to track them down.
IceCube uses a large volume of the South Polar Ice sheet as a neutrino detector.
IceCube deploys 5000 extremely sensitive light sensors distributed on
86 strings, which cover about 1 cubic kilometer at a depth of about 1400 meters.
The picture above shows the final light sensor being lowered into place. The
deep Antarctic ice is extremely dark and extremely pure. When neutrinos pass
through the ice, interactions between the neutrinos and the ice nuclei produce
high-speed particles called muons,
which actually travel faster through the ice than light (but slower than light
travels in vacuum). The muons produce a kind of "photonic
boom" as they pass through the ice, generating a brief flash of faint blue
light called Cherenkov
radiation. The IceCube detectors, in their otherwise perpetual darkness, can
detect these tiny flashes. IceCube recently made headlines when they found no
correlation between neutrino detections and the occurrence of gamma-ray bursts, all but ruling out GRBs as a source of high energy
cosmic rays. This helps point to a solution of the 100-year old mystery of the
origin of cosmic rays, and suggests that these cosmic rays are probably produced
black holes at the centers of active galaxies.
Published: May 14, 2018
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Page Author: Dr. Michael F. Corcoran
Last modified Monday, 21-May-2018 09:14:14 EDT