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Re: [Phys-l] Electron vs. Alpha particle...




In case you wondered; the Maraldi (sp), Arago or Poisson bright spot is the bright spot observable in the shadow of suitably adumbrating objects which was intended as a difficulty for the EM wave theory and which paradoxically provides an objection to a corpuscular theory which offers shadows only, a theory such as John D. mentions. I see the bright spot quite often on the ground when flying under a high Sun.

The Ramsauer-Townsend effect is a notch in the probability density graph of low energy electron - gas collisions (e.g. 0.7eV for a noble gas) which was difficult to explain in terms of a billiard ball theory which would provide a monotonic curve of probability vs electron energy.

Brian W

On 1/17/2011 1:16 PM, Bernard Cleyet wrote:
Does it include optical analogously** the Miraldi (Arago/Poisson) spot , and

is there a Ramsauer-Townsend for alphas?



** optically analogous?
bc


On 2011, Jan 17, , at 04:20, John Denker wrote:

(*) There is an exception for the forward direction, i.e. the
direction diametrically away from the source, associated with
the interference between the scattered wave and the other 99%
of the wave, i.e. the part of the wave that didn't scatter and
just kept going. We have a name for this: It is the /shadow/.