X-Message-Number: 13648
From: 
Date: Thu, 27 Apr 2000 08:14:46 EDT
Subject: uploading: choosing the x-rays

Here I continue my broad study of a Quantum Non Demolition
x-ray brain reader. Recall: it is a non destructive information recovery,
it works on fixed molecules (frozen brain or organs) and before a
full system can work, partial ones will teach us many things on
brain and biological functions.

We are mostly made up from water and hydrogen is a major
element in our body, on the other and, these atoms are not very
 interesting on the information side because we can deduce
where they are and what they do from the presence and position
of other atoms. So we want to have our radiations not absorbed by H.
This dictates a photon energy above 500 electron-volts. At the same time,
we are very interested by carbon, so the X-rays must be absorbed by a
small carbon quantity, we then limit the energy at 2000 eV. In that range,
we may be interested by more than one "color" (energy) to discriminate
further between atoms such carbon, oxygen, phosphorous and so on.

This  energy range is very different of the one choosen for medical x-rays:
Here, the radiation must find its way throughout hard parts such as bones.
In the QND interferometer, an interference patern cancel the wave
everywhere but on a thin slice inside the brain. The wave is always near
zero amplitude at the brain case level, so absorption here is not a concern.

Data on x-ray property can be found on line at:
http://pdg.lbl..gov
for low energy rays (30 eV < E < 1 Kev) see:
http://www-cxro.lbl.gov/optical_constants
For higher energy, see:
http://physics.nist.gov/PhysRefData

Yvan Bozzonetti.

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