What things can block x-ray imaging at airport customs?

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Offline sabali

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I'm writing a book about a group of criminals and just wanted to be really factually accurate.
So far I;ve heard Lead can , and carbon paper. if anyone can add to these two or expand on my question with a answer I would greatly appreciate it.

thanks
« Last Edit: 18/05/2013 21:06:59 by chris »

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Offline JP

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Things that block x-ray imaging at airport customs ?
« Reply #1 on: 26/11/2011 13:00:44 »
Very dense materials generally block x-rays well.  Lead and tungsten are frequently used.  Of course, if you put these in your luggage at an airport, you'd be pulled aside for "extra screening," since having a chunk of lead in your luggage is a sign that you're trying to hide something.

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Offline sabali

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« Reply #2 on: 26/11/2011 13:13:10 »
Thanks , Do you know alot about lead ?

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Offline RD

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« Reply #3 on: 26/11/2011 13:43:48 »
A few millimeters of metal isnít necessary enough to block X-rays :
you can see the truck's engine, as well as the illegal immigrants in the back ...


http://www.thenakedscientists.com/forum/index.php?topic=6326.msg254272#msg254272

https://en.wikipedia.org/wiki/Backscatter_X-ray
« Last Edit: 26/11/2011 13:48:07 by RD »

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Offline sabali

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« Reply #4 on: 26/11/2011 15:32:47 »
i suspect  those x ray machines are alot more powerful then the tiny ones that scan packages.
thats just logical.

im interested in hiding something concealed within a package

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Offline Bored chemist

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« Reply #5 on: 26/11/2011 15:59:37 »
RD, that's a backscatter image, so the xrays don't need to go through the engine to image it.
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Offline sabali

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« Reply #6 on: 26/11/2011 16:06:24 »
hey bored chemist i sent you a personal message :)

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Offline RD

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« Reply #7 on: 26/11/2011 16:52:33 »
RD, that's a backscatter image, so the xrays don't need to go through the engine to image it.

They do need to pass through the metal bodywork of the truck for the engine to be visible,
(bodywork could be Aluminium rather than steel)


[attachment=15575]
« Last Edit: 26/11/2011 17:05:12 by RD »

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Offline Bored chemist

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« Reply #8 on: 26/11/2011 16:54:49 »
If they didn't passsthrough that then they wouldn't be a lot of use for this purpose. The point is that the skin of the truck is quite thin.
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Offline sabali

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« Reply #9 on: 26/11/2011 17:11:31 »
check your inbox mate :)

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Offline CliffordK

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« Reply #10 on: 26/11/2011 17:34:55 »
As mentioned, the x-rays will pass through different substances at different rates, thus giving an image of what is inside of the container.  Presumably if something isn't showing up well, the intensity or exposure time can be increased.  Or they will do a physical inspection of the questionable object.

The biggest concern is to make one object appear like another.  

I.E. semi-liquid explosives could be put into toothpaste and shampoo bottles, which is why those items may be restricted from carry-on bags.  Of course, a detonator stuck to a toothpaste tube might show up in the scans.

Years ago I took a 110V/220V transformer to Europe with me which was a block of steel & copper wires weighing about 10 or 20 lbs.  But, even so, it probably had a very distinctive look in the X-Rays.  Modern laptop power supplies invariably take 110/220V, and thus all one needs is the proper plug adapters.

A well supplied terrorist undoubtedly would get access to a fluoroscopy machine for "testing" purposes.

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Offline chris

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Things that block x-ray imaging at airport customs ?
« Reply #11 on: 27/11/2011 10:38:34 »
The x-rays have definitely gone through the people because their lungs look nice and dark in the pictures. I'm very impressed at the quality of that image - it's good enough to do diagnoses of TB almost. I wonder if that's part of HMRC's cost-cutting initiative - save money by screening people and trucks on the way into the country...
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Offline Bored chemist

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« Reply #12 on: 27/11/2011 10:50:10 »
Knowing the HMRC they are more likely to use the technology to assess the quality and hence the true value of the bananas.
I agree that they xrays go through the people (twice), but, again, that's hardly news.
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Offline SeanB

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« Reply #13 on: 27/11/2011 20:09:33 »
The whole truck scanner does use a very high power source, to get the detected signal out of the noise floor. Note there is no driver inside, as otherwise he would be regularly exposed to a very high dose of very ionising radiation. not good for the hidden passengers, and probably quite capable of fogging any undeveloped film inside the truck, possibly even possibly erasing flash media ( bye bye truck engine management, and any electronics on board the truck) in the path.

Airline scanners hopefully are not as high powered, as they do not need to penetrate a few inches of steel plate.

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Offline damocles

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« Reply #14 on: 27/11/2011 21:31:46 »
The principle of X-ray examination is that different atoms reflect or absorb X-rays differently. So the main thing that X-rays show up is the atomic composition of whatever material they pass through/fail to pass through/reflect off. In most situations X-rays pass easiest through light atoms (hydrogen, carbon, nitrogen, oxygen), and with more difficulty through heavier atoms (phosphorus, sulfur <iron, nickel, copper <silver <gold , mercury, lead)

The most favourable likely thing for your international criminals to have in their package would be uncut diamonds (carbon), and to disguise them by mixing in with a pack of scorched almonds or similar (also mostly carbon & oxygen). The only thing I am not sure of is whether the x-ray scanner would pick up suspicious diffraction rings or spots from the crystalline nature of the diamonds which would not be so clearly produced by the chocolates. Similarly most drugs are not detectable by X-ray machines, but they do have sniffer dogs at airports!
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Offline Bored chemist

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« Reply #15 on: 28/11/2011 18:47:58 »
OK, so I know that the manufacturer's website is hardly an unbiased opinion but it seems that the Xray dose isn't very big.
http://www.saic.com/products/security/vacis-xpl/
My guess is that the driver isn't in that vehicle because he is talking to Customs about his cargo.
Once they see the image they will want to talk at more length.

I'm fairly sure that x ray scanners don't produce diffraction images because it would need monochromatic Xrays and the image would be horrible convoluted.
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Offline damocles

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« Reply #16 on: 28/11/2011 20:50:24 »
I'm fairly sure that x ray scanners don't produce diffraction images because it would need monochromatic Xrays and the image would be horrible convoluted.


The most common/simplest type of X-ray generator has an electron beam at several kV impinging on a metal target -- often copper. It therefore provides not a monochromatic source, but certainly a line spectrum with few lines, and CuKα dominating. While it is very likely that a scanner image would be too convoluted for diffraction spots or rings to be detected, I would not be totally sure of that.

The brochure that can be downloaded from the linked manufacturer's site says, inter alia,

Quote
Powerful imaging performance

The VACIS XPL systemís switched-energy X-ray source simultaneously screens vehicles at two
different energies, displaying organic threats such as explosives, stowaways and drugs in a
different color to help inspectors quickly evaluate the vehicleís contents. The system also
provides conventional high-resolution black-and-white X-ray images to help inspectors
identify metallic threats such as guns.
The system can image passenger cars and light trucks from roof to pavement and bumper to
bumper, allowing the entire vehicle to be quickly and efficiently screened.


"Two different energies" implies a fairly efficient monochromator, and effectively a pair of monochromatic scans. I think the real issue about detecting diffraction would come with spatial resolution and convolution rather than wavelength convolution. Diffraction spots are much weaker than a direct through-beam or a specular back-scatter, and their presence would not generally be welcome in an imaging procedure anyway (they would tend to blur and confuse the image).
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Offline Bored chemist

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Things that block x-ray imaging at airport customs ?
« Reply #17 on: 28/11/2011 21:24:24 »
""Two different energies" implies a fairly efficient monochromator, and effectively a pair of monochromatic scans."
Or it implies two different acceleration voltages and "optimistic" writing.
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Offline CliffordK

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« Reply #18 on: 29/11/2011 09:15:59 »
The most favourable likely thing for your international criminals to have in their package would be uncut diamonds (carbon), and to disguise them by mixing in with a pack of scorched almonds or similar (also mostly carbon & oxygen).
[...]
Similarly most drugs are not detectable by X-ray machines, but they do have sniffer dogs at airports!

Diamonds (and drugs) are non metallic.  So, as long as the airports are using simple metal detectors for people, then it would be possible to carry them on (or in) one's body.  The new whole-body scanners may not be at a high enough power to pick up non-metallic stuff in the GI tract.

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Offline JP

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« Reply #19 on: 29/11/2011 14:11:32 »
""Two different energies" implies a fairly efficient monochromator, and effectively a pair of monochromatic scans."
Or it implies two different acceleration voltages and "optimistic" writing.


I believe most airport X-ray baggage scanners use a wide bandwidth source and a dual energy detector, which allows the separation of the high and low-energy X-rays.

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Offline JP

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« Reply #20 on: 29/11/2011 16:00:57 »
I'm fairly sure that x ray scanners don't produce diffraction images because it would need monochromatic Xrays and the image would be horrible convoluted.

Generally, they don't do diffraction imaging, but there is ongoing research into it, particularly for medical X-ray imaging. 

In addition to sources being polychromatic (you can use a monochromating crystal to fix this), the other big problem with X-ray sources is that they are fairly spatially incoherent.  To fix the coherence problem, you can use a microfocus source so that the source is within the coherence width of the X-rays, or you can use a coherent source of X-rays (which tend to be very large, such as synchrotrons).  In most practical situations in medical imaging or X-ray scanning, microfocus sources are used when diffraction imaging is required.

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Offline Don_1

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Things that block x-ray imaging at airport customs ?
« Reply #21 on: 29/11/2011 18:10:32 »
As far as your book is concerned, if anyone turns up at an x-ray station with bagage that's shielded from x-ray's, methinks alarm bells will ring for the operator. What's more, even before you get that far, humping around a lead lined suitcase might attract some attention.
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Offline CliffordK

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Things that block x-ray imaging at airport customs ?
« Reply #22 on: 29/11/2011 20:11:25 »
Personally, I believe that a well funded terrorist group could develop the technology to smuggle significant weapons onto planes.  But, I will choose not to speculate on specific methods in an open forum beyond generalities that are already obvious, or are in use by dope smugglers.

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Offline damocles

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« Reply #23 on: 01/12/2011 03:15:16 »
""Two different energies" implies a fairly efficient monochromator, and effectively a pair of monochromatic scans."
Or it implies two different acceleration voltages and "optimistic" writing.


No, BC -- the X-rays generated are line spectra of the target element, and only the intensity is affected by the electron energy. That is why when a continuous or continuously tunable x-ray source is required something much more expensive like a synchrotron is needed.

The picture, which clearly shows the immigrants through a mettal shell, is not indicative of an overly  "optimistic" brochure.

By the way, the "two different energies" would be either the Kα and Kβ lines of the target metal, or the Kα and Lα lines.

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Offline Bored chemist

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« Reply #24 on: 01/12/2011 19:22:23 »
Yes Damocles, by changing the voltage you can change the spectrum.
Have a look here
http://www.helmholtz-berlin.de/forschung/funkma/werkstoffe/methoden/xrd_en.html

If you use a heavier metal like Tungsten you can get quite a range of continuum radiation without the characteristic line spectra complicating things.
This would, of course, be hopeless for diffraction, but the consensus seems to be that they are not doing that.

Oh, BTW, if you want monochromatic Xrays it's common to filter the output from a tube to isolate the lines even more by using the absorbtion edge of another element.
Like this
http://www.helsinki.fi/~serimaa/xray-luento/xray-absorption.html
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Offline Don_1

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« Reply #25 on: 06/12/2011 13:19:16 »
If brains were made of dynamite, I wouldn't have enough to blow my nose.

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Offline imatfaal

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« Reply #26 on: 07/12/2011 09:52:02 »
Agree again - but whilst general science is the subject we are happy to continue, no specifics tho please
Thereís no sense in being precise when you donít even know what youíre talking about.  John Von Neumann

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Offline CliffordK

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Things that block x-ray imaging at airport customs ?
« Reply #27 on: 07/12/2011 11:27:07 »
As I wrote here http://www.thenakedscientists.com/forum/index.php?topic=42244.msg374914#msg374914, so the same applies in this case.
I have only one thing to say, if there is a genuine, viable means by which to prevent a dog detecting drugs or explosives in a suitcase, it would be irresponsible to put such information into the public domain. So if there is a method and you should stumble upon it, keep it to yourself eh!

Yeah,
I already wrote:

Personally, I believe that a well funded terrorist group could develop the technology to smuggle significant weapons onto planes.  But, I will choose not to speculate on specific methods in an open forum beyond generalities that are already obvious, or are in use by dope smugglers.

Anyway, the newspaper is always a good source for the latest criminal ideas.  Also, popular movies and TV shows, although they often get their facts off a bit.

Masking the smell of drugs as well as explosives has been a commonly published technique, and isn't always foolproof. 

For a while I've had some specific ideas on how one could smuggle weapons past airport security, but I agree that they are best left unpublished.

Perhaps what the TSA and DHS needs is a confidential tip line for community ideas of how to bypass security.  It would take a lot of effort to analyze the viability of the ideas though, and more effort still to plug the potential security holes, and some security holes would be difficult to plug.

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Offline redfandango

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Re: Things that block x-ray imaging at airport customs ?
« Reply #28 on: 07/05/2013 14:13:48 »
hi all - does anyone know if dense soundproofing material such as Tecsound t50 (<spammy link removed>) or acoustiblok would block an x-ray or what colour it would show up as on the blue / green / orange spectrum?
« Last Edit: 05/10/2013 19:31:41 by chris »

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Offline damocles

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Re: Things that block x-ray imaging at airport customs ?
« Reply #29 on: 08/05/2013 07:55:12 »
hi all - does anyone know if dense soundproofing material such as ???? would block an x-ray or what colour it would show up as on the blue / green / orange spectrum?

(1) Why are you wanting to know this about a particular product?

(2) In general terms because "soundproofing material" involves sound waves and X-rays are light rays, there is no real correlation.

(3) Because the particular material is "polymer based" it will only have light elements in it, and therefore be almost transparent to X-rays.
« Last Edit: 21/11/2013 16:21:04 by peppercorn »
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Offline redfandango

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Re: Things that block x-ray imaging at airport customs ?
« Reply #30 on: 08/05/2013 15:16:01 »
Thanks for your answer.

I ask specifically in relation to the development of a commercial travel product. 

The correlation we had imagined to be based around density - these products claim to be as dense as lead of the same surface mass and therefore we considered that it may have the same effect as lead on an x-ray i.e; turn black.  YOu seem to suggest this would not be the case based on the material fabrication however would the density not play a part?

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Offline damocles

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Re: Things that block x-ray imaging at airport customs ?
« Reply #31 on: 11/05/2013 01:03:21 »
Sorry red, but you have really caught my imagination! What sort of "commercial travel product" are you thinking of? As far as I can see, all that your use of a product like this would achieve would be to have you pulled aside from the general airport security queue for a detailed search, which would simply cause a delay without achieving anything other than probably making you miss your flight. Are you free to disclose more about it?
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Offline shippingexpertise

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Re: What things can block x-ray imaging at airport customs?
« Reply #32 on: 16/11/2013 19:01:18 »
Hello,

I am sorry to write here but as you seem expert and I cannot find a solution I dare to ask your help.

I would like to send a bottle of liquid by post but it is forbidden in my country and Xray always catches my parcel.

Do you know how I could do ?

Put some foil for example ?

And do you know if they see the bottle that I send because of its shape of they really see the liquid that is inside ?

Thanks a lot for your help.



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Offline RD

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Re: What things can block x-ray imaging at airport customs?
« Reply #33 on: 16/11/2013 20:00:53 »
I would like to send a bottle of liquid by post but it is forbidden in my country and Xray always catches my parcel.
Do you know how I could do ?
Put some foil for example ?.

Foil-wrapped items would be glaringly-obvious on an X-ray.

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Offline damocles

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Re: What things can block x-ray imaging at airport customs?
« Reply #34 on: 16/11/2013 21:15:48 »
I would like to send a bottle of liquid by post but it is forbidden in my country and Xray always catches my parcel.

Do you know how I could do ?

You should be asking yourself a few questions:
-- Why is it forbidden to send liquids by post? (safety issues: risk of breakage and spillage; airmail: will the item be transported by air at any stage, or risk of explosion from pressure buildup in a sealed container)
-- Is the liquid really being detected by Xrays? (remember that the postal service has dogs trained to sniff out drugs or explosives, and even if your liquid is innocent of either of these charges it is possible that it may be providing a false positive, or that dogs might be trained to detect other substances, e.g. alcohol)
-- Should you be checking the fine print of the postal regulations? (for example, in my country, Australia, it may be possible to transport small amounts of liquid provided that the bottle is packed in a much larger box in vermiculite, and that the postal service/courier is aware of the nature of the shipment)
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Offline RD

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Re: What things can block x-ray imaging at airport customs?
« Reply #35 on: 16/11/2013 22:35:32 »
You should be asking yourself a few questions:
-- Why is it forbidden to send liquids by post? (safety issues: risk of breakage and spillage; airmail: will the item be transported by air at any stage, or risk of explosion from pressure buildup in a sealed container)
You forgot religious reasons : sending a bottle of Scotch to friends in a Saudi Arabia is a no-no.
[ they won't be your friends afterwards ]

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Offline CliffordK

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Re: What things can block x-ray imaging at airport customs?
« Reply #36 on: 17/11/2013 00:27:29 »
I didn't realize international mail was that restrictive.  I don't believe it is so restrictive in the USA, although I can't think of the last time I either shipped a liquid, or had one shipped to me.

I'd check with different shippers.  Here we have a plethora of parcel shippers.  Is your parcel being shipped by air or land?

Find out more exactly what the rules are.

X-Rays will pass through thin foil.  A good system should be able to automatically adjust the field intensity/exposure for different materials and requirements.

You should have a good seal on any liquid container so it won't leak during shipping.  It should be either an unbreakable container, or have enough packing that it won't break.  And, perhaps have a secondary seal in case the primary seal breaks. 

No shipper will want your vial of something leaking all over their load.

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Offline alancalverd

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Re: What things can block x-ray imaging at airport customs?
« Reply #37 on: 17/11/2013 09:50:13 »
Don't use the high street post office.

We have no problem shipping radioactive liquids around the world with scheduled passenger aircraft and licensed couriers - it's the safest way to deliver medical and industrial supplies. Read and follow the IATA Dangerous Goods Regulations and the requirements for Type A packaging. If you need Type B packaging you will have to charter a freighter rather than a scheduled passenger flight, and you will need a rather more specialised surface courier, but it's all perfectly normal.

If the liquid is not dangerous, just use a private courier - even a bike or taxi if the job is sufficiently valuable. People transport everything from water to petrol by air, road, rail and sea every day.

Why try to cheat and risk prosecution?
helping to stem the tide of ignorance

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Offline chiralSPO

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Re: What things can block x-ray imaging at airport customs?
« Reply #38 on: 17/11/2013 16:06:11 »
Sabali,

Everything blocks x-rays to some extent, but this is frequency dependent. I don't know what wavelength they use, but the main issue is how far an xray can penetrate before being adequately blocked. Everything has a different degree of stopping power, but generally heavier atoms are more efficient than lighter ones. Also, the more closely packed the atoms are, the better their collective stopping power. These two trends essentially insure that the denser a material is, the shorter the penetration will be.

Just going by density, the top ten pure elements are:    *prices as googled while writing this post, subject to change...
osmium (22.6 g/mL, $380/Oz*)
iridium (22.4, $450/Oz)
platinum (21.5 $1450/Oz)
rhenium (21.0, $3500/Oz)
uranium (20.2, $36/lb!!!)
americium (19.8 $160000/g!!)
tungsten (19.4, $47/kg)
gold (19.3, $1289/Oz)
neptunium (19.0 $660/g)
tantalum (16.7 $160/lb)

As you can see, some of these are impractical from a pricing standpoint (though I am surprised at how low some of these prices are... Of course, no one is going to have any luck trying to get uranium, americium or neptunium on a plane (I hope). If you tried making an americium or neptunium box large enough to cover anything, you would probably kill yourself before even getting to the airport. Also, osmium, iridium, platinum, rhenium and tungsten would be nearly impossible work into a useful shape without some serious equipment and know-how. Pretty much leaves you with gold. They also might just be able to sneak something EXTREMELY valuable or sensitive in a gold item without arousing too much suspicion (though this would probably involve declaring the gold teapot and looking wealthy enough to have it...)

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Offline Bored chemist

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Re: What things can block x-ray imaging at airport customs?
« Reply #39 on: 17/11/2013 16:55:54 »
Tungsten foil is a commercial commodity, Lead is easy to roll out into foil, (though it's only roughly half as dense, it scores more highly than you would expect because it's not just density that matters- it's the atomic number (more strictly, the number of electrons but that amounts to the same thing).

Making a lead foil bag to put something in would be easy.
However the practical outcome would be to draw attention to the package and it's contents.
So the security staff would just crank up the power on the Xray system until they could see through it.
You are not going to win that way.

And it's hardly in our interests to help you break the law.
Please disregard all previous signatures.

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Offline alancalverd

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Re: What things can block x-ray imaging at airport customs?
« Reply #40 on: 17/11/2013 17:43:48 »
A couple of technical points

Depleted uranium is dirt cheap, and quite a bit is already used in aircraft structures as control surface balance weights. No problem carrying it on board if you really must, though it is a bit radioactive and unpleasant to machine - the dust tends to ignite spontaneously.   

Ordinary baggage inspection machines use dual energy x-ray imaging. The ratio of transmission between 140 kV and 60 kV x-rays is useful to spot nitrogenous explosives, and anything that isn't penetrated by 140 kV radiation will be hand-searched, so wrapping your stuff in lead or tungsten foil will just ensure that it is confiscated.

Far better to declare it as exempt cargo, or declared dangerous goods if it is dangerous. 

You can carry small quantities of liquid explosives through hand baggage "security" by relying on human gullibility - I've seen it done, but it's pointless. If you have an innocent reason for transporting them, ship as much as you need through the declared cargo route. If you want to destroy the plane as a passenger, you can get all the stuff you need on the airside, quite legitimately, and it won't make a ha'porth of difference to the contempt we all feel for the morons who do it.   
helping to stem the tide of ignorance