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Liquid scanner

One other blogger has asked how well does it work ? (http://www.travelsupermarket.com/blog/liquid-x-ray-scanners-in-airports/) and is it going to lower security ?

A new device which can tell what the liquid is inside a bottle. It appears to work by looking at absorption at different wavelengths of X-rays.

If you look at a graph of absorption for an element such as lead against photon energy there are some peaks due to excitation of the electrons in the atoms. The only problem is that the X-ray photons for elements such as carbon are very low in energy and are unable to pass through air, I am not quite sure of how it will work.

I think that the machine needs to be able to measure the carbon, hydrogen and oxygen concentrations in an object if it is to be able to tell the difference between tea and vodka.

One alternative would be to use a pulsed neutron source combined with an energy dispersive gamma ray detector, this allows for a series of different elements to be measured. I have read how the US military use such a device to identify artillery shells which contain chemical weapons.

Many explosives (TNT, picric acid, semtex) contain nitrogen so one of the key reactions is

n + N-14 –> p + C-14 + gamma photon




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