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Do X-rays Reflect in a Mirror?

08/14/2006 5:30 PM

I have asked several tech people in the x-ray equipment field and not yet gotten a satisfactory answer to this question- perhaps someone here can enlighten me. When an x-ray source is behind a shield can it be safely viewed with a mirror (e.g., are the x-rays absorbed by the glass or to they reflect from the front surface of the glass)? DATA: Mirror is 1/4-inch thick, common borosilicate glass, "silvered" on the back surface. Angle of incidence is 45 degrees. X-ray energy is the copper K-alpha emmission line, (wavelength=1.54 angstroms= 1.54*10e-10 meters), (energy= 8.04 Kev= 1.29*10e-15 joules). -Bill Morrow

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The Engineer
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#1

Absolutely Not

08/14/2006 5:55 PM

Quote:"(e.g., are the x-rays absorbed by the glass or to they reflect from the front surface of the glass)?"

The answer is neither, the xrays will travel through the mirror as though it was transparent. X-rays are highly energetic photons that can cause a lot of damage. A thick lead screen will stop X-rays (because of the density of atoms).

Optical properties of visible light do not translate to X-Rays, its apples and oranges.

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#2
In reply to #1

Re:Absolutely Not

08/15/2006 1:54 AM

That makes sense. Early research with dry radioactive piles was done using lead blocks and mirrors to facilitate remote manipulation. Just be sure to keep out of the hot zone!

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Guru

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#3

X-rays

08/15/2006 4:46 AM

The first guy is correct. X-ray do not reflect from normal mirrors. However there are materials that can be used as x-ray optics. Don't quote me, but I think beryllium is one. On the down side, x-rays react with materials at a VERY shallow angle! Almost parallel to the surface. If you want to see how an X-ray telescope works, take a look at the Chandra probe or its replacement. To make the objective lens, plates are combined in circular rows where they're surfaces are almost paralell to the incoming x-rays. The same is done for what would act as the eye piece. Anyway check out NASA (you might have to do a little digging) if you want to see how x-ray optice are handled. Regards, Vermin-

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Associate

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#4

X-ray Reflectivity

08/15/2006 8:39 AM

The term for shallow angle x-ray optics is "grazing incidence" optics. Beryllium is used for x-ray windows so it should be transparent to x-rays. There is always some x-ray reflection from all sorts of materials ("backscatter"), but it is not much. There are some digital x-ray units that produce so little backscatter that 6 feet away is sufficient to attenuate it all. To be completely safe, one could use the mirror and a transparent x-ray shield (looks like thick, brownish-colored plastic) to intercept the backscatter.

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Guru
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#7
In reply to #4

Re:X-ray Reflectivity

09/03/2006 12:33 PM

If you use x-ray mirror then you can reflect the x-rays. However ordinary optical mirrors can't do this.

You can also divert path of x-rays in crystal planes, nano-tubes even up to 180 degrees, which we may call reflection. It is different from visible light interaction with polished metals surfaces.

We even have x-ray lasers now.

Shyam

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Guru
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#5

Re:X-Ray do reflectable. Check the link first!

08/15/2006 12:41 PM

I have found it useful to put all linked URL's at the bottom of my posting and simply refer to them in my text. That way I do not get the underlining in my text.

Is there another work-around for this problem?

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The Architect
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#6
In reply to #5

Posting links on CR4

08/16/2006 8:55 AM

Hi STL
We're going to be releasing a new version of the CR4 web site ver soon (within a month) that will make linking (and other formatting) much easier and cleaner looking. Hopefully that will address the problem.
Thanks
Mark

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Guru
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#8

Viewing x-rays

09/03/2006 12:42 PM

Well you can't see x-rays, but you can see low energy secondary emission from mirror or for that matter from any surface where x-rays can lose energy and under Compton scattering low energy photons can move towards your eye. We generally place some phosphor that does this efficiently. You can try that white powder in FL tube light bulbs. Remember that it is a bit toxic material to clean your hands after using it. It is Lithium Fluoride compound with some low rare-earth activator atoms.

This just happens to be my field of research work for many years now.

Shyam

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Anonymous Poster (1); Bayes (1); DaveMeador (1); mgaulin (1); Shyam (2); STL Engineer (1); vermin (1)

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