Gamma Spectrometry Forum

Hi Everyone,

I just thought I'd share this spectrum I took. I was using Theremino's s Deconvolution on this but I will try Steven's software and PRA soon. Nothing about this spectrum is unusual, except for the way it was taken.

My setup -

1. A Theremino 3.3 PMT adapter
2. A LaCl3(Ce) detector (small 30mm x 30mm crystal)

These two have been installed into a Well Logging tool housing. It is a stainless steel pipe about 2.5 feet long. 2.3" OD an 2" ID (so roughly 1/8th wall thickness). This tool connects to 1558 feet of wireline cable. Wireline cable is 4 conductor 22-24 gauge wires inside of stainless steal inner and outer strands. This is meant to be used with a winch and you log the borehole for whatever a person might want. That could be coal, uranium, potash, or other minerals. Of course oil and gas exploration happens as well, but the company I work for are mineral loggers.

I was able to hook up this makeshift tool using the soundcard method over 1558 feet and at a depth of 215 feet in the borehole. This is a limestone formation. You will notice the pronounced Potassium, but part of the Lanthanum Chloride detectors have some inherit peaks and one of these is just about where potassium is on the spectrum. Most of the time, limestone has very low KUT values so I think part of that at 1450 or so is a peak that the detector itself puts out.

So, why did I even do this? Because I had an idea and wanted to see if I could do it. It took me a couple of months and a little bit of money for that detector but I accomplished what I set out to do. The company I work for does not currently have a tool that can do this. They are still using the OLD methods of 256 channels and three wide windows for KUT. This method traces its roots to the 1950's.

I do have other reasons for doing this than just to see if I could do it. So, there is a legitimate purpose for this but not using a soundcard. It would need to have a real MCA with digital output.

I tried to add some other images of the winch and test hole but it kept giving me a format error message. I don't know why, because they were small files and .jpg

Anyway, I just though someone might find this interesting. I asked Grok the AI if it could find of any others that may have tried this and it said NO :)

Sincerely,
Anthony

Nice work Anthony.

With all the money at stake, I would have thought advanced borehole spectroscopic logging tech would be far more common.
Glad to see your already putting that detector to good use.

Cheers, Tom

Thanks Tom,

Well, the large companies like SLB are using neutron activation and looking at the gamma spectrum. The rest of the middle tier companies are just getting the idea in their head.

The main tool that has been used since at least the early 60's is known as the Spectral Gamma Logging Tool (AKA - KUT tool). It typically has about 256 channels (bins) and each of those bins represents about 12 keV. They log the tool up slowly and have three very wide windows that cover the range of typical peaks like 1460, 1760, and 2620 for KUT respectively. These windows are very wide and at each depth interval, they sum up all the cps in each window. Then this summed up cps is converted to PPM or Percent by way of calibration. It is a way to quickly get an idea of the amount of each element. It does work but it is prone to error. Definitely not a spectral analysis. They use ratios like Th/k to determine mineral type and other lithology. It really is the industry standard. However, some companies have started to realize that using LaBr3, those windows can be narrowed and the results much more accurate. These tools are now being used more often because rare earth elements are being found near certain mineral types. REE's are the thing that the President and DOE are pushing for because of our reliance on China.

The only time a real spectrum would be extremely useful is U238 disequilibrium. They have methods that they have used since the 70's where they go by Kfactor and Deadtime and some DOE pit calibration of known u238 concentrations. However, they are only measuring counts. So, they "grade" the Ore like this. But, the really big thing would be to also provide a quick disequilibrium assessment by taking a spectrum of 5 - 10 minutes. This would give them confidence in the Ore Grade. People have attempted this using HPGe since the 1980's. My company even tried it. It was a disaster. Everything was expensive, the tools had internal Stirling coolers that required long cooling times, and then they had limited time to actually log the holes. The disequilibrium assessments worked but it was too expensive and too much trouble. In the end, they abandoned that project. That is where I am going with this. Use LaBr3 and possibly software deconvolution functions to find the peaks and determine if the uranium is good. Nobody is doing this now but we recently had a meeting with some uranium companies and they definitely want this kind of thing, So my focus is on that.

There are other good applications this could be use for. It's just a matter of getting the company to realize all this and spend a little money. Once they saw that spectrum, they immediately wanted to know how we could do testing using conventional digital methods.

Anthony

Also, I should mention that in my setup, the PMT adapter and detector were in the downhole tool. On the surface is a small power supply to send 5 volts down the line. Then the PMT adapter returns the analog signal over that length of cable. People told me it would be real noisy and I honestly doubted it would work. But I have a good grounding scheme and some inline hi pass filters on the signal coming in. There really isn't noise of any kind. I've seen worse in my office - LOL. I also used some ferrite beads on the wireline cable and some of the power cables

iRad wrote: ↑

05 Apr 2025, 13:40

Nice work Anthony.

With all the money at stake, I would have thought advanced borehole spectroscopic logging tech would be far more common.
Glad to see your already putting that detector to good use.

Cheers, Tom

Hi Tom,

I'm sorry but I didn't realize who you were. Yes, the detector I got from you is great and was worth the money. My only issue is it needs to be bigger. It struggles to get to higher energies. That's not your fault. That's just the way they are. So, the detector is great. And as you can see, it is able to work downhole and over long distance

Thanks,
Anthony

Anthony,

Thanks for creating an interesting post. Amazing that you are getting these results with an analogue signal through that long cable, I have been telling customers to try and keep the cable length below 5 meters, but this may not be the limit. Would you be able to share the make and number of the cable you used ? Sounds like a special non stretch cable.

Steven

Steven,

I sent you an email about the whole thing but here are the wireline cable specs. Believe me, I didn't think this would work and was jumping up and down when I did the surface test

Anthony

I did take a couple of short videos when I did the initial surface test and when I finally got it down the hole. It was meant for people who had never heard of sound card spectrometry. I am from Oklahoma so I do sound like a dork. But hey that's me :)

https://aro365697754-my.sharepoint.com/ ... 0&e=EXPG9j

https://aro365697754-my.sharepoint.com/ ... 0&e=p35WrQ

I'll try to make some better ones. Btw - I was using the cheap chinese sound card on this but I also have a Focusrite Scarlett Solo device. It does act like a sound card but it's more for people who are plugging up instruments or microphones. It seems to work pretty well. But really, the $5 sound card works about the same