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Flash x-rays and phosphors

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c4r0

Wed Mar 26 2008, 01:37PM

Registered Member #151 Joined: Sun Feb 12 2006, 02:53PM
Location: Poland
Posts: 153

Harry wrote ...
Good work, Karol! A very interesting and informative page! Well done!

Thanks

Now I have to translate the rest of it :)

plazmatron wrote ...
As you have already realised the x-ray pulse from flash setups is VERY penetrating, and it would be advisable to design some sort of shield for the tube, or at least be FAR away from it when it is running

Actually I thought that low energy x-rays (about several keV) are more dangerous than than high energy x-rays. By the way I bought a leaded apron a few days ago, it should arrive soon. Maybe it's time for a hand x-ray?

plazmatron

Wed Mar 26 2008, 06:03PM

Registered Member #1134 Joined: Tue Nov 20 2007, 04:39PM
Location: Bonnie Scotland
Posts: 351

c4r0 wrote ...
Actually I thought that low energy x-rays (about several keV) are more dangerous than than high energy x-rays. By the way I bought a leaded apron a few days ago, it should arrive soon. Maybe it's time for a hand x-ray?

Yes from an absorbed dose perspective you are correct, as high kVp x-rays will drift through the human body, without causing much damage to tissues. However, the setup described on my page, will undoubtedly generate broad-band x-ray emission from ~50kev to 300kev.
The other factor to be taken into consideration is Compton scattering, where for example a dense material in an x-ray beam, will absorb high energy x-ray photons, and emit lower energy x-ray photons.,and this secondary emission should be taken into account.

The bottom line is, take all the reasonable precautions you can, it is always good to have a healthy level of respect for apparatus such as this!

As for hand x-rays, the maximum permissible level of radiation to the hands is considerably higher than to any other part of the body,which is a plus. BUT,having said that, there were several cases around the turn of the 19th Century, that doctors, and the employees of x-ray tube manufacturers lost hands, by repeatedly exposing them to x-rays to test that their tubes were working! X-rays are very good at killing tissue, in a large enough single dose, or repeated low doses.
I must confess I myself have given into the temptation and made a couple, and I`m ok, BUT, I wouldnt recommend it. Its something YOU decide for yourself, after you have weighed up the risks. X-rayed hands really arent that exciting, and cancerous stumps are even less exciting!

My hand on a MS mouse ^

Leslie

Bjørn

Wed Mar 26 2008, 06:59PM

Registered Member #27 Joined: Fri Feb 03 2006, 02:20AM
Location: Hyperborea
Posts: 2058

I see that you are right handed.

plazmatron

Wed Mar 26 2008, 07:41PM

Registered Member #1134 Joined: Tue Nov 20 2007, 04:39PM
Location: Bonnie Scotland
Posts: 351

LOL well spotted!

Proud Mary

Wed Mar 26 2008, 11:55PM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

I have been wondering if the discharge of the Marx bank through the tube could be considered as the discharge of a capacitor through a resistor, with the t = CR model of decay, (and so decay of X-ray energy spectra over time} or whether more complex processes may be at work due to oscillations, rectification, and the like.

c4r0

Thu Mar 27 2008, 07:40PM

Registered Member #151 Joined: Sun Feb 12 2006, 02:53PM
Location: Poland
Posts: 153

And here it is :D

Proud Mary

Thu Mar 27 2008, 11:20PM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

Bravo, Karol! When first I saw the joke picture of your red face posted above, I thought you had completely lost your mind - and given us all a bad name as dangerous fools too.

Tonic

Thu Mar 27 2008, 11:45PM

Registered Member #528 Joined: Fri Feb 16 2007, 10:32PM
Location: Warsaw, Poland
Posts: 166

Now you're looking much scarier, like as mad scientist or surgeon ;) By the way, what's a thing on left arm?

c4r0

Fri Mar 28 2008, 07:57AM

Registered Member #151 Joined: Sun Feb 12 2006, 02:53PM
Location: Poland
Posts: 153

It's a laser burn on the CCD sensor

I was making closeup pictures of working scanners in a Big Dipper K800 disco laser. I'm lucky that I've damaged my cheap compact instead of my brothers DSLR camera

c4r0

Sun Mar 30 2008, 08:19PM

Registered Member #151 Joined: Sun Feb 12 2006, 02:53PM
Location: Poland
Posts: 153

Hmm, my little finger looks strange... The image quality is poor becouse it was made with intensifying screen and digital camera. 1,6s exposure time, 90kVp. I have a lack of time now, but I'm going to do such x-ray again on the photographic paper soon. What do you think about x-ray of hand holding a soldering iron (transformer type) on my avatar?

BTW according to my military G-M counter the apron attenuates the radiation a few hundred times (it is equivalent to 0,5mm Pb). My x-ray setup gives 66 Sv/h (from Rad Pro Calculator -

- 1mm Al 90kV 20mA 50cm distance), scattered radiation is in position 1% of main beam, so about 0.7Sv/h. So if my apron gives 500x attenuation my body (excluding head and arms) gets ~0.4uSv in one second exposition. I know that this is only estimation, but is this dose level possible?

Leslie, did you use an Al filter when x-raying yourself? And what was the anode voltage (the ms mouse x-ray)? Looks like it was high energy x-rays.

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