[JP]

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.

[Don_1]

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.

[CliffordK]

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.

[damocles]

""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.

[Bored chemist]

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

[Don_1]

As I wrote here http://www.thenakedscientists.com/forum/index.php?topic=42244.msg374914#msg374914, so the same applies in this case.

[imatfaal]

Agree again - but whilst general science is the subject we are happy to continue, no specifics tho please

[CliffordK]

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.

[redfandango]

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?

[damocles]

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.

[redfandango]

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?

[damocles]

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?

[shippingexpertise]

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.

[RD]

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.

[damocles]

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)

[RD]

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 ]

[CliffordK]

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.

[alancalverd]

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?

[chiralSPO]

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...)

[Bored chemist]

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.