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From: jeric@tybalt.caltech.edu (J. Eric Grove)
Newsgroups: sci.misc,sci.physics
Subject: Re: differences between sound and light waves?
Message-ID: <5564@cit-vax.Caltech.Edu>
Date: 25 Feb 88 17:39:44 GMT
Sender: news@cit-vax.Caltech.Edu
Reply-To: jeric@tybalt.caltech.edu.UUCP (J. Eric Grove)
Organization: California Institute of Technology
Lines: 33

In article <98@aoa.UUCP> carl@aoa.UUCP (Carl Witthoft) writes:
>In article <5537@cit-vax.Caltech.Edu> jeric@tybalt.caltech.edu.UUCP (J. Eric Grove) writes:
>>In article <3129@bloom-beacon.MIT.EDU> jfc@athena.mit.edu (John F Carr) writes:
>>>The blue glow is the result of massive (i.e., not massless)
>>>particles losing energy as they slow to the speed of light in water.

>>Note that this statement is misleading.  Charged particles lose about 3 orders
>>of magnitude more energy in ionizing the medium they are traversing than in
>>generating Cerenkov radiation.  Typical ionization energy losses for
>>		J. Eric Grove

>What's going on here? I thought that the whole point of
>Cerenkov radiation was that it is a "bow wave" of light given off
>by a particle moving faster than the speed of photons in the present
>medium.  The radiation is somewhat like a sonic boom.
>
>Alix's Dad ( Carl Witthoft @ Adaptive Optics Associates)

Yes, I should have been more specific.  Certainly the blue glow is Cerenkov
light, and certainly the charged particles are losing energy to this radiation;
however, the slowing down is dominated by ionization of the medium.

It is also true that if the charged particles are electrons, then in this
relativistic regime, energy loss to bremsstrahlung is also quite large.

The classic text on Cerenkov radiation, _Cerenkov Radiation and its
Applications_, by J. V. Jelley is an excellent source (as you might have
guessed from "classic").  The introduction provides a nice summary which I
think should be approachable by anyone with a little physics, and chapter
2 presents the classical theory (understandable if you've done some E&M).

		J. Eric Grove
		jeric@tybalt.caltech.edu
		...rutgers!cit-vax!tybalt.caltech.edu!jeric