Where do cosmic rays come from?

News from the IceCube Neutrino Observatory at the Amundsen-Scott South Pole Station:

Results of a recent experiment there on the origin of cosmic rays has contradicted 15 years of predictions.  The electrically charged particles making up cosmic rays bombard the earth all the time, but scientists do not fully understand how they are created.  One theory posits that they are a byproduct of Gamma-ray bursts.   Gamma-ray bursts are very powerful emissions of electromagnetic energy.  Most occur in galaxies billions of light years from ours as a result of supernovae or the merger of binary neutron stars.

The IceCube Observatory has been looking for neutrinos in conjunction with Gamma-ray bursts.  Co-author Dawn Williams of the University of Alabama–Tuscaloosa said:

“With the IceCube lab, this is the first time any detector has been large enough to predict the flux of neutrinos. We can make predictions of how many neutrinos we should be seeing from these gamma ray bursts.”

But the researchers did not find any neutrinos associated with GRB.

Williams says:

“(The results) will affect theoretical GRB studies, so we will have to take a serious look at their models for what goes on after one of these explosions.  The main message is that we’re still looking.”

Here are five facts about the IceCube Observatory:

1. From Gizmag we learn that the observatory was completed in December 2010, after 5 years of summer season work.

2. The IceCube Observatory current news section tells of the collaboration publishing a paper last year on the “Search for dark matter from the Galactic halo with the IceCube Neutrino Telescope.”

3. Redorbit says that IceCube has thousands of spherical optical sensors called PMTs (photomultiplier tubes) at depths of 4750 to 8000 feet. They are on strings of sixty modules each, arrayed in holes melted by hot water drilling.

4. Seedmagazine, in a lengthy, interesting article on the observatory, quotes IceCube investigator Francis Halzen: “I like to say we’re building butterfly nets for ghosts.  The ultra-transparent Antarctic ice itself is the detector. And a real bargain at just 25 cents per ton!”

5. Finally, the International Polar Year site tells us why the IceCube observatory had to be built at the south pole.  To do the experiment involving neutrino detection scientists needed the purest and thickest ice on the planet.  Where else but Antarctica?


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