Re: Pinhole Radiography

From: G.Penate <penate_at_domain.name.suppressed>
Date: Thu 08 Mar 2001 - 05:07:43 PST

----- Original Message -----
From: "Jeff Pryor" <pryorjm@ornl.gov>
> Could someone help me with some design calculations for a gamma wave
> camera. I have done some of the preliminary calculations and I guess that
I
> don't belive the numbers, or more likely just don't really know what I am
> doing. This should be a very interesting project and a little bit of your
> time would be most helpful.

Gamma wavelength are very small, in the order of 0.000000001mm, reverse
engineering the formula I use for visible light pinhole imaging gives me a
(very rough) formula for gamma wavelength pinhole imaging of

Diameter or pinhole = 0.00005 SQRT(focal length)

Assuming you can make a pinhole as small as 0.1mm in diameter, that pinhole
would be (if I am not mistaken with the formula above) "optimum" for a focal
length = 4 Kilometers or 2.5 Miles!! and that is a very big show box or
Quaker oatmeal cylinder!!

For a focal length of 10" , you'd need a pinhole = 0.0008mm!!

Besides, you will have to find a material to make the pinholes that gamma
rays are not able to pass through (not sure if steel, brass or aluminum
would fit the bill).

Guillermo
Received on Thu Mar 8 19:41:25 2001

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