Needing more than a spark test?

That sounds about right to me, although I don't understand this statement:
"they have drop-out delays characteristic of their electron energy states."
Any time delay would not be relevant and only due to chance. It is the amplitude of an individual signal that equates to energy and would be characteristic for a specific element's electron shell. Or do I misunderstand the statement?
Robert
 
hman said:
Now a specific question for graham-xrf: Looking at post #31, I did not see this type of electron multiplier listed in the table. Was I simply missing the nomenclature? Or was it not included????? And could you use either a night vision image intensifier (which I think you said you had on hand) or a Channeltron instead of a PMT?
Click to expand...
Firstly - thanks for the Auger electron explanation. The lines of spectra that can happen from where some electron energy states impinge a bit on lower levels, or are variously shielded depending on whether an electron was knocked out of a lower shell, gets a bit complicated, to say the least.

Regarding the intensifier types in the table post #31. The tables were from the Hamamatsu webinar, which would have been all about Hamamatsu products. These might not include image intensifiers incorporating micro-channel plate structures. The old salvaged example I have of was a (I think) a Generation 3, and may by now be poisoned by helium ingress (can helium go through glass)?

The type you describe are now very developed, very efficient things, devoted to night vision, so probably optimized for visible and infra-red wavelengths, and generally output to a green screen - so not for directly providing the multiplied electron collection to an amplifier.
 
rwm said:
That sounds about right to me, although I don't understand this statement:
"they have drop-out delays characteristic of their electron energy states."
Any time delay would not be relevant and only due to chance. It is the amplitude of an individual signal that equates to energy and would be characteristic for a specific element's electron shell. Or do I misunderstand the statement?
Robert
Click to expand...
From what I read, when an electron in an atom structure is driven into a higher energy state, the time it takes to return, and deliver up the photon at a quantum defined wavelength is not random. It can drop out in nanoseconds, or up to hours, depending on the element, and depending on which states the transit was between. Was I wrong about that? It is possible. I am taking in much of this stuff really fast (for me).

This think it now begins to look like it has a chance, enough for me to risk getting hold of enough stuff for the first experiment, gathering up some circuits stuff, and giving it a try. It may get somewhere, or it may strike out sadly, but we will never know unless we get up something to beat up on alloy steel, and see if we can figure out what it gives up.
 
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Some information about CsI(Tl) scintillation crystals. Also, a lot of other info.

CsI(Tl) - Cesium Iodide (Tl) Scintillator Crystal

Cesium Iodide, activated with Thallium - CsI(Tl) - is one of the brightest available scintillators, with a broad emission peaking at 550nm. CsI(Tl) has good stopping power, physically rugged and and well suited to a broad range of applications.
www.advatech-uk.co.uk www.advatech-uk.co.uk
 
RJSakowski said:
Some information about CsI(Tl) scintillation crystals. Also, a lot of other info.

CsI(Tl) - Cesium Iodide (Tl) Scintillator Crystal

Cesium Iodide, activated with Thallium - CsI(Tl) - is one of the brightest available scintillators, with a broad emission peaking at 550nm. CsI(Tl) has good stopping power, physically rugged and and well suited to a broad range of applications.
www.advatech-uk.co.uk www.advatech-uk.co.uk
Click to expand...
Thanks RJ.
What we now need to get to is the range of wavelengths to expect from the steels, after being hit by Americium energies, so to decide which scintillator material best suits it. Must not forget to include carbon, and cobalt, and silicon.
 
I think carbon will be difficult. It has a very low cross section for x-rays. Page 6 of the document in post #9 gives the wavelengths of all the elements. The upper energy will be the 59.7 Kev of the Americium source.
 
Auger (pronounced oh-jhay since the effect is named after a French physicist) electrons only come from the surface. Just throwing a sample into the machine and hitting it with electrons won't actually reveal what the bulk material is -- it will show what's absorbed on the surface. Typically carbon from organics that were absorbed from the environment. A real auger system includes an ion gun to erode/mill the surface away at a known rate so it can be used to generate a profile of all the elements vs depth.

The vacuum system for Auger analysis also has to be _extremely_ clean, or stuff from the chamber or pumps will deposit on the sample and lie to you about what's really there. An LN2 cold finger + turbo pump + scroll pump for backing the TMP are needed, none of which are within a hobbyist's price range. The pump system alone would be upwards of $10K unless you can score some good deals on ebay. Then there's the ion gun....

EDX and WDX use high energy electrons that penetrate deeper into the sample so they're better at telling you what the bulk material is without requiring an ion mll.
 
After browsing around ebay for PMTs and scintillators it looks to me like the scintillator-PMT approach is the way to go. Buy 'em and proceed with the project, rather than getting yourself into the position of needing to buy/make tools to make what you want. In addition, that approach has already been shown to work. Why re-invent the wheel if you don't need to??

Scintillators also should be better suited for detecting lower-energy x-rays. When you start getting down into the 5kev range, the window material for ionization detectors becomes crucial -- that's why beryllium is the material of choice. A scintillator doesn't have that problem.
 
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I may build one of these if someone figures out the electronics. It would be so cool to have. Are the support electronics for a commercial PMT complex?
Robert
 
The main thing a PMT needs is a stable high voltage power supply (they actually are very simple devices). The dynodes are biased with a resistor-divider string, and the raw output is a current pulse, needing either a passive element (i.e., another resistor) or relatively fast current-to-voltage converter. The PMT's gain is determined by the high voltage so that's why the HV needs to be stable.
 
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