X Ray of Different Material

[Shadow_Talons]

Disclaimer: This forum is an open discussion about x raying of different materials. Being a newbie, this is my first post so be nice. I've done a search on x ray on this site and did not turn anything up. Some interesting sites came up on a quick google search about x ray's.

LIXI X-Ray Security came up with this link http://www.lixi.com/x-ray-security.htm

In the image of the pen, it shows hidden electrontics. Does any one know how different materials show up on x ray detectors? What about metals like steel, silver, and gold and do objects behind the material show up on the scan?

Open discussion, this should be interesting.

[Jacks Complete]

Your search skills are weak. Searches only work on words over 3 letters long. Try searching for "backscatter x-ray". However, it is an interesting link.

[Alexires]

*sigh* Did you do a search for x ray or x-ray? Because if it was the first one, there will be no results returned as the search engine on this forum doesn't process anything with 3 letters or less.

If you did a search of roguesci.org using google and used "x ray" you would have found 112 results.

Now, from memory, all metals will show up on x-rays. It has to do with the density. Naturally, something more dense (like lead) will show up on an x-ray scan more than something less dense (say normal air). I think it might have something to do with outer shell electron energy levels, but that could be something else. Its been a while.

Edit: It has to do with absorption. As I understand it, the x-rays can be absorbed in 2 ways. Either the x-ray hits the nucleus and imparts all its energy to the nucleus and produces heat, or it "interacts" with the electron shell and produces other wavelengths of light. Naturally, if the material has electron energy states capable of interacting with the x-ray, then the % absorption will be greater than something that only relies on a direct hit to the nucleus.

But don't take my word for that (I'm hardly a definitive source on this), do some searching. Physics books will help you, and physics pages on the net.

Also, we don't really care if you are a newbie. Saying "Be nice, I'm a newbie" is like saying "Be nice, I'm stupid".

Compared to some people, you will always be a newbie, as will I.

So just get over it.

[rayman]

Shadow_talens, Welcome to the board, There has as Alexires said been threads on this.

Alexires, Where I agree with you, I think its the Mod team members that should comment on most of what you said, And being a user of the forum not part of the mod team maybe you should ( just a thought ) be more helpful with newer members as we should be trying to support each other so that we can all grow, instead of saying "you didnt use the FSE properly" maybe you could have said "the SE works better this way .... "

Wording means alot, Not attempting to start a pissing contest or anything, BUT we are all here to learn and share, There is no reason for any of us to start off a newbie by pissing in his corn flakes


Just my 2.2 cents

I'm betting this post gets me some type of ban

[Hirudinea]

I've heard that aluminium has same absorption as flesh so it won't show up in the soft tissues of the body, which is why its illegal to make weapons that produce aluminum shrapnel, but I don't know how that could possibly help you. :)

[Alexires]

You are complete right rayman. That probably was a little harsh, but I didn't intend it to be so.

Basically, if you want to re-word it, I contributed what I knew, but didn't care enough about the subject to put in hours of searching myself.

It also irks me a little when newbies tell me to be nice to them because they are new.

It also seemed to me from a few hints that he wants info without actually doing the work. Unless you're blind and brain dead, when you click search, you will see the google search bar above the rs.org search.

Fair enough if you don't understand that it will pick up things the normal search doesn't get, but then he goes say that he did a "quick search" for x-rays, hinting that he (like me) couldn't be bothered to do some research. Hell, I probably did more searching looking for x-ray absorption than he did.

And then finally, he goes on to say "open discussion" like we needed his divine blessing to talk about the subject after his bounty of useful and wonderful information.

So, although it may seem like I'm trashing you Shadow_Talons, I'm not. Those were just little personal things that shat me off.

Welcome to The Forum *grin*.

On topic, this (http://hyperphysics.phy-astr.gsu.edu/hbase/mod3.html) explains fairly well how x-rays work.

Look for something like x-ray transparency in google. When I get the chance to in a few weeks, and if this still hasn't been sorted out, I'll ask a physics Prof at uni.

[Ygarl]

And now for a USEFUL answer to your question.
By x-rays, I must assume you mean freight and baggage x-ray machines.
In this, you are most fortunate as I spent a stint as an air-freight security officer. On one site I was part of a team x-raying every piece of freight going onto DHL's aircraft out of London Heathrow, and going onto land-cargo from the depot which was not already security cleared. At another site, I was responsible for ALL the freight going out which was not security cleared. Both sites used x-ray machines big enough to stand in, and big enough to put a Mini through (the tiny car, I mean of course).
In any case, the relative absorbsion of various substances is colour-coded. Completely x-ray opaque items show up black, highly x-ray absorbent materiel (dense metals i.e. iron/steel, bronze, brass, etc.) show up blue, moderately absorbent materiel (aluminium, maybe copper, etc.) shows up green, and organic materiel shows up orange.

An organic explosive for instance would show up as a orange shape with green wires/leads trailing out of it, to a blue/green shape with wiring throughout and one or more solid black masses attached to it (batteries).

A firearm generally shows up as a black and indigo gun shape, with perhaps some orangey parts for plastic on the grip, etc.

The shades of colour show the varying densities of the materiel. Essentially, an experienced tech on the x-ray machine can learn to recognise suspicious items with a high degree of accuracy.

Realistically however, in air freight (NOT passenger flight btw!) we get a huge pile of bags at 40kg at a time, and get told to x-ray an entire 4 tons of freight piled to the top of the machine (some 2 meters) at the same time. We were lucky to see obvious KNIVES, let alone subtle differences between explosives and cheese, or wood, or stacks of paper or any other organic materiel.

So, to finally answer your question: Aluminium shows up green or blue depending on if it's alloyed and what with. Steel/iron shows up blue/black depending on its thickness. I don't remember silver or gold, but since a quite thin piece of lead shows up as black I reason that silver would show nearly black tinted blue, and gold black unless very thin as in foil or perhaps a thin chain.

*I* would search a package manually which showed lots of black or blue ingot shapes! ;-)

[Hirudinea]

subtle differences between explosives and cheese

So you would suggest shiping explosives in big wheels of cheese? :)

Would you still have any training manuals, colour pictures of exemplars going through the machines, ect., that you could upload, those could be quite interesting to the people here.

[rayman]

Alexires, We all make mistakes, My self I have so many interests that I cant search for every think I need to know, Every now and again being given a little information helps me alot, But I dont ask to be feed. Some times just knowing the right term to search for is such a big help, But to the person that has been involved in that area for a while would find it to be a silly or stupid question.


Anywho before I write two or three pages on it ..... " its all good " comes to mind

[Ygarl]

So you would suggest shiping explosives in big wheels of cheese? :)

Not a bad idea actually. The ideal thing to do would be to find substances which have the same x-ray density on a freight machine.

Unfortunately, the problem is getting access to a proper machine to test it.
I know a training centre literally across the street from Heathrow which may be amusing to visit late at night perhaps...

I don't have any training materials unfortunately, as I took the course 5 years ago or so. The machines have quite a high definition, and I have been able to read text on some plastic and metal items in the machine in the past.

I've moved on since then - mainly as they were paying about £5.45ph to their staff and working 37 hours a week. So you were taking home about £120 a week after taxes! Hell, my rent was £250 a month at the time!
Let's just say: don't ship anything you want to keep through DHL unless it is valueless in economic terms (or LOOKS like something valueless) or it will go missing! You can make double the money on welfare here!

[Alexires]

Ygarl - You could always loiter around airports keeping your eyes open for bags that aren't attended. Then you could slip your cheese explosive into their luggage or whatever you are trying to test.

If they get busted, it didn't work. If they get through, then you won't hear anything about it.

Will something of a lesser absorbency (eg. an organic material) inside something of a greater absorbency (a Cu or Al tin) show up on x-ray as the correct colour or would it be masked by the metal?

[Ygarl]

Tricky...

A lesser-density item in a greater would show as one colour inside the other A blue larger object, say, with a yellow-er (?) one inside it - showing as greenish-orange etc.

The only exception would be if it was x-ray opaque, but then that would leave it open for a manual inspection, and who wants people pawing through their cheese? Hahah

Particularly if your Gouda or Jarlsberg was likely to explode if tampered with!

Absorbsion is an important part of x-ray visibility, as is scattering (reflection and diffraction) away from the camera/detector. To clarify - if the x-rays are diverted away from their paths away from the detector, they will effectively appear darker or denser on a real machine. X-ray flat surfaces have been developed for space-telescopes, etc.

[Alexires]

Now Ygarl, as I understand it, the computer in the x-ray machine adds its own colour to the picture that you are seeing.

So, for a 5-10% loss in signal strength the machine would colour that orange, for a 10-20% loss green, etc.

How can the machine tell that the loss in signal strength is from one object inside another and not simply from having a varying thickness of only one object, if you get my meaning?

I suppose that multiple source points of x-rays would allow for a differential approach, but still, its asking a bit much of the machine.


Damn, but for some reason, thinking of a cheese bomb is so incredibly amusing.

[Ygarl]

Hmmm... Thinking about it - a lesser density inside a greater one would show up DARKER and BLUER - not Green/Orange. I was thinking backwards there.

But it would still be visible as the absorbsion would be higher overall.

Sorry about that! Neurons still short of caffeine I guess...