Re: cherenkov radiation [ cosmic ray origin ]

[Justin Wilde <jlwilde@eng.utah.edu>]

Try the following link, they discuss many cosmis ray detectors

http://www.physics.utah.edu/Resrch.html

including the high resolution fly's eye

On Wed, 6 Dec 2000, Franta, Jaroslav wrote:

> Date: Wed, 6 Dec 2000 06:39:24 -0600 (CST)
> From: "Franta, Jaroslav" <frantaj@aecl.ca>
> Reply-To: radsafe@romulus.ehs.uiuc.edu
> To: Multiple recipients of list <radsafe@romulus.ehs.uiuc.edu>
> Subject: Re: cherenkov radiation [ cosmic ray origin ]
> 
> 
> Dukelow, James S Jr wrote on Wednesday November 08, 2000 6:04 PM
> 
> <snip>
> Cherenkov "glow" can occur in air, even dry air, where it is the basis for
> an
> "instrument", the STACEE (Solar Tower Atmospheric Cherenkov Effect
> Experiment),
> that uses a heliostat array and a photomultiplier to detect the atmospheric
> trace of particle "showers" caused by extremely high-energy gamma rays
> arriving
> from active galactic nuclei. 
> <snip>
> 
> Last Sunday serendipity produced a find of an old article that includes some
> interesting information on Cerenkov radiation originating from cosmic rays.
> 
> Its an article I ripped out of an old issue of Scientific American, called
> "The Highest Energy Cosmic Rays" (no date on any of the pages, but its
> probably from ~10 to 15 y ago.
> 
> The interesting part is where the author talks about these cosmic rays, with
> up to 10^19 to10^20 eV energy ("about as much as a very well hit tennis
> ball" - and much more that any existing man-made particle accelerators are
> capable of...) inducing a mile-wide secondary etc. particle shower along
> their trajectory, several kilometers up in the atmosphere (ie. still a
> fairly large aspect ratio - with a long, narrow beam path). 
> This "disc" of particles, moving at about the speed of light, emits a bright
> beam of Cerenkov radiation directly ahead along its path ("like a locomotive
> searchlight"). 
> This is easy to detect on a clear night, but the camera must be located &
> pointing directly in the path of the incoming particles - which at this
> extreme energy level is a fairly rare event - perhaps a few per month  ( the
> original cosmic ray particle, incidentally, is NOT an extremely high-energy
> gamma ray, but is typically an atomic nucleus - of anything from helium to
> iron, etc. ).
> The article describes several detectors around the world built to track
> these rare events, one being the "Fly's Eye" near Salt Lake City, Utah (also
> trying to detect a very much fainter fluorescence from these events, which
> is emitted omnidirectionally, and therefore more suited to tracking a larger
> portion of the events and their point of origin in the sky.)
> 
> Presumably there should be an astrophysics web site somewhere on the net
> that gives more details on this ?
> 
> Jaro
> frantaj@aecl.ca
> 
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