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trinitree88
2010-Mar-01, 08:18 PM
It's a fun thing for little kids to see their first shadow by the full of the moon...(even trickier to see it by Venus). The Earth has shown it's shadow in the diurnal oscillations of the Sudbury Neutrino Observatory, at ~14%....now the moon's shadow is showing up in Ice Cube, the string of suspended detectors that pick up Cherenkov showers. See:http://arxiv.org/list/astro-ph/new


pete

peteshimmon
2010-Mar-01, 08:23 PM
So the Universe is full of muons? I wonder
what they all weigh.

trinitree88
2010-Mar-01, 08:31 PM
pete. I can't open my new link. The universe isn't full of them, they're created by cosmic ray splatter (spallation) on the upper atmosphere. Relativistic muon velocities enable them to penetrate the atmosphere and reach the ground (or Ice Cube). So I think the muon deficit is due to cosmic ray splatter on the moon. There should be some interesting papers on the moon's regolith contents, partially contributed by those same cosmic rays over eons, that are from the LCROSS impact. pete to pete

peteshimmon
2010-Mar-01, 08:38 PM
OK thanks Pete. I was being just a little
vacuous though the shadow notion seemed to
suggest a universal flux. And the negative
charge would presumably cause galactic muons
to predominate from some directions.

There was a story of particles being
detected from the direction of Cygnus X3
some years ago I think.

Jerry
2010-Mar-01, 11:28 PM
Here is a permanent link:

http://arxiv.org/PS_cache/arxiv/pdf/1002/1002.4900v1.pdf


I don't recall reading about a plan to use moon shadows to calibrate the Ice Cube array. Did they plan this, or did they look at the data and figure out they have a built-in baseline calibration tool?

mantiss
2010-Mar-02, 06:51 PM
"My God, it's full of Muons..."

I know *gag* :)

BigDon
2010-Mar-02, 06:58 PM
Weren't the Muons the bovinoids from Cestus 3?

trinitree88
2010-Mar-02, 07:26 PM
Here is a permanent link:

http://arxiv.org/PS_cache/arxiv/pdf/1002/1002.4900v1.pdf


I don't recall reading about a plan to use moon shadows to calibrate the Ice Cube array. Did they plan this, or did they look at the data and figure out they have a built-in baseline calibration tool?

Jerry. Thanks for the link. New IT guys at work have put some kinks in my links. The idea originated with G.Clark in 57, and has been used in detectors intermittently since. An object as massive as the moon ought to shadow every particle flux known to some degree. pete

loglo
2010-Mar-03, 06:55 AM
I always wondered what Cat Stevens was singing about.

ngc3314
2010-Mar-04, 03:20 PM
We have an IceCube colleague just down the hall. She says that, since using the lunar shadow for cosmic-ray charge discrimination is an old idea, they were aware of it from the outset, but did it only when they had enough detectors in the ice for it to work (IceCube 22, I think it was).