Hello all! I've been sitting on this spectrum for a week or so, trying to figure it out on my own. This is from a thorium lantern mantel, which I collected with my 4 inch home made probe. I cropped it down to a maximum of 2.6MeV for readability. What I'm struggling to understand is the twin peak at 80 and 91 keV. I'm assuming it is X-Ray, but I haven't seen anyone else with a spectrum like this.
Any ideas?
Strange Twin Peak - Th232
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Geoff
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Strange Twin Peak - Th232
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Last edited by Geoff on 27 Oct 2017, 18:12, edited 3 times in total.
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Sesselmann
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Re: Strange Twin Peak - Th232
Geoff,
Are you using a lead shield?
Are you using a lead shield?
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Geoff
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Re: Strange Twin Peak - Th232
No, I was unshielded for this spectrum. I'm on the second floor of my wood house, working on a wooden desk. I wasn't too worried about background radiation as I have a background spectrum I can subtract and I know what the sample was. I was just trying to get everything set back up after quitting my job. This is the first time I've collected a Th232 spectrum. I thought I must have set something up incorrectly, but after running it 3 times I always get the same result.
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Sesselmann
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Re: Strange Twin Peak - Th232
Geoff, I have a Thorium lantern mantle, I can try to run a spectrum with my XRF detector and see what shows up at the lower end.
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brehwens
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Re: Strange Twin Peak - Th232
Hi!
As far as I can recall, you will see two XRF peaks if you have a detector with good resolution. I also remember seeing this with one of my probes, so congratulations!
sometimes you can miss this if too much "smoothing" is applied to too few counts, so it can sometimes be nice to look at the raw unsmoothed graph in order to spot these things...
As far as I can recall, you will see two XRF peaks if you have a detector with good resolution. I also remember seeing this with one of my probes, so congratulations!
sometimes you can miss this if too much "smoothing" is applied to too few counts, so it can sometimes be nice to look at the raw unsmoothed graph in order to spot these things...
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Boris
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Re: Strange Twin Peak - Th232
Hi Geoff,
Could this be the energies of the daughters 74.96 keV (Pb-208), 77.1 keV (Bi-212) and 93.3 keV (Th-228)?
Cheers, Boris.
Could this be the energies of the daughters 74.96 keV (Pb-208), 77.1 keV (Bi-212) and 93.3 keV (Th-228)?
Cheers, Boris.
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Geoff
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Re: Strange Twin Peak - Th232
I appreciate it Steve! I want to collect a spectrum using my new RAP47 probe, but I seem to be having a hard time getting the settings right.
Karl, good to know I got it right, even if by accident. The twin peaks were very prominent, even before plotting the data in excel.
Boris, I'm not sure if it is. I only did a rough calibration with Ra226, so I'm not positive where the peaks are exactly. I plan to re do the spectrum, but need to buy a new PMT.
Karl, good to know I got it right, even if by accident. The twin peaks were very prominent, even before plotting the data in excel.
Boris, I'm not sure if it is. I only did a rough calibration with Ra226, so I'm not positive where the peaks are exactly. I plan to re do the spectrum, but need to buy a new PMT.
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Sesselmann
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Re: Strange Twin Peak - Th232
Geoff,
It's been kinda hectic around here so it has taken me a while to do this, but as promised I ran a spectrum on my old (Geo supplied) Thorium lantern mantle with my XRF detector (crystal donated by Karl) . Although not as pronounced separation as your spectrum, the two peaks can be clearly seen.
Obviously there is a lot of stuff going on in Thorium once it reaches secular equilibrium, but my best guess is that it would be Th228 at 84.4 KeV and Ac228 at 99.5 KeV
Open to other suggestions...
Steven
It's been kinda hectic around here so it has taken me a while to do this, but as promised I ran a spectrum on my old (Geo supplied) Thorium lantern mantle with my XRF detector (crystal donated by Karl) . Although not as pronounced separation as your spectrum, the two peaks can be clearly seen.
Obviously there is a lot of stuff going on in Thorium once it reaches secular equilibrium, but my best guess is that it would be Th228 at 84.4 KeV and Ac228 at 99.5 KeV
Open to other suggestions...
Steven
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lodovico
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Re: Strange Twin Peak - Th232
Hello to everybody,
it could be the XRF K and L lines of thorium ?
Attached there is a gamma spectrum of thorium mantle (the low energy part) acquired with NaI(Tl) 25x25mm + PMT + theremino.
The spectrum was acquired outside the lead castle, inside the castle the K lines of lead is dominant.
Regards,
Lodovico
it could be the XRF K and L lines of thorium ?
Attached there is a gamma spectrum of thorium mantle (the low energy part) acquired with NaI(Tl) 25x25mm + PMT + theremino.
The spectrum was acquired outside the lead castle, inside the castle the K lines of lead is dominant.
Regards,
Lodovico
You do not have the required permissions to view the files attached to this post.
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Geoff
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Re: Strange Twin Peak - Th232
No worries Steve, as a new university student I understand hectic all too well. Thanks for the spectrum. I'm going to try to get my big crystal back in operation this week. I have a PMT that will work, but I need to finish making a voltage divider.
