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Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
IntraWinding wrote ...
Proud Mary wrote ...
IntraWinding wrote ...
Will you use a crystal of some type as a diffraction grating, or have I got the wrong end of the stick?
As an absolute beginner, I'll have a go with simple crystals to get an XRF energy dispersion spectrum, Alan.
Wavelength dispersion analysis with monochromators, verniers, and what have you is beyond my very modest constructional skill, intellect, and economy.
You think you're a beginner! I don't even understand your answer!
Aha, I didn't mean to be vague! What I should have said is that there is no set of plans or diagrams for me to follow but my own, and no obscure sorority of amateur X-ray spectroscopists for me to join and learn from, so I have to make it up as I go along.
Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
radhoo wrote ...
I love the project, however this is also very expensive. The x-ray flash-tube, the high voltage capacitors and all the other equipment.
Looking forward to your next update.
Thank you very much for your encouragement, Radhoo!
I will be starting another thread on making ionisation chambers after Christmas. My idea is to describe in detail the construction of a good quality but inexpensive and easily built chamber which will have repeatable performance, so long as the design is copied accurately. The experimeter will know that if there is a given voltage across the tube, and so many μA are flowing, then the dose rate is so many Gy/hr.
Registered Member #30
Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706
Proud Mary, I recently found this book in archive.org with some interesting articles on X-ray diffraction methods. Interestingly, you don't need a pure crystal, it can work with lots of little crystals, a powder, etc.
Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
Steve McConner wrote ...
Proud Mary, I recently found this book in archive.org with some interesting articles on X-ray diffraction methods. Interestingly, you don't need a pure crystal, it can work with lots of little crystals, a powder, etc.
"Chou-fleur" indeed. :D
That's very kind and thoughtful of you, Steve, but I have that title already - and you are right - it does indeed contain details of experiments, discoveries, and equipment much more accessible and repeatable by the enthusiast than the cryptic, jargonised scribblings in the peer-reviewed literature of today..
I suppose that much of the experimental equipment of that era was designed by one or two people, while the shop-bought X-ray spectrometer of today would involve a team of specialists, each of whom would deal with just one part of the project, so no one has to be at once a nuclear physicist, mathematician, electronics engineer, radiolological safety officer, software writer, machine tool operator, and trade union shop steward all rolled into one.
Registered Member #1938
Joined: Sun Jan 25 2009, 12:44PM
Location: Romania
Posts: 701
Proud Mary wrote ...
I will be starting another thread on making ionisation chambers after Christmas. My idea is to describe in detail the construction of a good quality but inexpensive and easily built chamber which will have repeatable performance, so long as the design is copied accurately. The experimeter will know that if there is a given voltage across the tube, and so many μA are flowing, then the dose rate is so many Gy/hr.
That would be inspiring. I'm curious to see what solution will you find for the high-ohmic resistor required to turn the few uA (or perhaps pA) into a few volts to amplify that further. Reading online I've seen a solution using a neon lamp, carefully painted (not to touch the terminals) or covered in some black plastic, but that didn't work for me. So if possible a DIY solution to replace this expensive component would be interesting.
Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
radhoo wrote ...
Proud Mary wrote ...
I will be starting another thread on making ionisation chambers after Christmas. My idea is to describe in detail the construction of a good quality but inexpensive and easily built chamber which will have repeatable performance, so long as the design is copied accurately. The experimeter will know that if there is a given voltage across the tube, and so many μA are flowing, then the dose rate is so many Gy/hr.
That would be inspiring. I'm curious to see what solution will you find for the high-ohmic resistor required to turn the few uA (or perhaps pA) into a few volts to amplify that further. Reading online I've seen a solution using a neon lamp, carefully painted (not to touch the terminals) or covered in some black plastic, but that didn't work for me. So if possible a DIY solution to replace this expensive component would be interesting.
BR, R.
You can buy 10G resistors for £1.30 (6.66 RON) and 50G resistors for £1.22 (6.25 RON) from Farnell, here:
But in fact no such very high value is needed in my design, which is for measuring X-rays in Gy/hr - not tiny background dose rates for which ionisation chambers are unsuitable for serious measurement.
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X-Ray Spectrometer
What I should have said is that there is no set of plans or diagrams for me to follow but my own, and no obscure sorority of amateur X-ray spectroscopists for me to join and learn from, so I have to make it up as I go along.
