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----- Original Message -----
From: Dude <dfemer@...>
To: [email protected]
Sent: Thu, 24 Oct 2019 20:04:55 -0700 (PDT)
Subject: Re: [XRF] OK Dude, how do we excite those RE's above 50 keV clkeanly and how to detect it.

Hi Randall,
Yes you never know what state you may be looking at and the ion abundances are different. Are you referring to Ritz vs Observed wavelengths?
Lines will move up very slightly with an increasing ionization state. The ionization state II is generally the strongest.
Dud

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Randall Buck
Sent: Thursday, October 24, 2019 11:21 AM
To: [email protected]
Cc: [email protected]
Subject: Re: [XRF] OK Dude, how do we excite those RE's above 50 keV clkeanly and how to detect it.

Hi Dud,
Don't you have to pay attention to ionization states greater than one and the consequent line shift, when using LIBS ?

Randall



----- Original Message -----
From: Dude <dfemer@...>
To: [email protected]
Sent: Tue, 22 Oct 2019 21:30:20 -0700 (PDT)
Subject: Re: [XRF] OK Dude, how do we excite those RE's above 50 keV clkeanly and how to detect it.

My 50kV gun is limited to 50 kV due to the backscatter and the FDA shielding issues. The SSD drops off pretty quickly at about 60 keV for the photoelectric response unlike CdTe which can see the U Ka at 98 easily. A Si Pin is similar to the SSD in range but much poorer in resolution. Both depend on the depletion depths and peaking time. The problem is efficiency at the high energies. I can see Sm with a 50 kV xray but it’s got to be in the percent range. I have a Kevex 60 kV xray microfocus unit here but no detector other than some low energy HPGe’s to use with it. I had been toying with the idea of picking up a Cd Te detector to play with. A fast SSD would really help with resolution.

U and Th La’s are easy to see.

The problem with the HREE is you have to look at the La and Lb’s which occur in the matrix of everything else and don’t resolve well. Using the Ka, Kb’s requires a 50kV tube up to Pm. Above that you want to be about 10 -20 keV above the binding energy. U and Th occupy a fairly open region above the mess below and are easily seen in the La and Lb range.

Rather than cooling down the HPGe detectors I look at the HREE with a homebrew LIBS system which see everything.

I’ll be looking in to a CdTe detector but I’m sure I’d also be tempted to get a Fast SSD for the Kevex.

What are the specs on your SiPin? Window and SI thickness? What do you have for the CdTe setup?

Dud

From: [email protected] [mailto:[email protected]] On Bto the SDehalf Of GEOelectronics@...
Sent: Tuesday, October 22, 2019 3:50 PM
To: [email protected]
Subject: [XRF] OK Dude, how do we excite those RE's above 50 keV clkeanly and how to detect it.



Does your SDD go above 50 keV?

The Si-Pin really falls off sharply, @59.5 is by no means blowing it away, while the X-Rays are fantastic.

Over the winter I'll try to get the CdTe sensor online... but have to make a set of cables first between power supply/shaping amp and sensor/preamp head......it's supposed to be good from 5 to above 100 maybe even to 200, but no microfocus exciter in that range....

Recently I accidentally ID'ed uranium by XRF- the rock was not labeled and I didn't suspect it to be radioactive, but there were those U XRF lines right on the button. Will try something with thorium soon.



Geo