Nuclear Pioneer MCA RIID gamma spectrometer

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Matrix
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Re: Nuclear Pioneer MCA RIID gamma spectrometer

Messaggio da Matrix » 09/11/2021, 22:12

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09/11/2021, 21:44
Thank you for the reply. Just out of curiosity is that the NIST Eu152 standard?
Nuclear Pioneer channel-to-energy scale can be calibrated with one of the calibration schemes from the menu. When scheme is selected, I only need to pick positions of the peaks centroid to point the software to the correct channel number. It will calculate the calibration polynom coefficients by auto.
For example Eu-152 scheme uses: 122keV, 344keV, 1408keV
and Cs-137/K-40 scheme uses: 32keV,662keV,1460keV

there are additional schemes in menu.


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cipndale
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Re: Nuclear Pioneer MCA RIID gamma spectrometer

Messaggio da cipndale » 14/11/2021, 11:32

So, as I understand it, the calibration for efficiency is done with a 3rd party software.



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Matrix
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Re: Nuclear Pioneer MCA RIID gamma spectrometer

Messaggio da Matrix » 14/11/2021, 11:55

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14/11/2021, 11:32
So, as I understand it, the calibration for efficiency is done with a 3rd party software.
The device has pre-programmed energy to efficiency fuctions for a different types of geometries & crystal. The functions derived with Monte Carlo simulations.
To calibrate the efficiency of the acitivty calculator the device require only to select correct geometry in menu and set the factor. If you have a calibration source of Cs-137 with known activity it very easy to set the factor after several measurements of the source activity in situ. The main parameter is correct geometry has to be selected prior the test, proper positioning of the probe with the source and performing 3-5 meausrements to get the factor. Every probe due to difference in the enclosure material thickness and crystal dope% has some variance of the efficiency at 662keV. The factor that you can find experimentally helps to compensate it. Defualt value is 1.0, in practice the factor will differ a little bit.

After the factor set with Cs-137, you can test with a different isotope at same geometry to be sure that evryhting is fine. For example with Ba-133.
4.08 software can calculate activity for Cs-137, Ba-133, Ra-226. Am-241 still under test since I don't have the proper source with exactly know activity.


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Matrix
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Re: Nuclear Pioneer MCA RIID gamma spectrometer

Messaggio da Matrix » 01/01/2022, 22:17

New 4.09 firmware released with supporting Eu-152 in RIID's library.
IMG_5281.JPG
IMG_5295.JPG
IMG_5306.JPG
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Matrix
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Re: Nuclear Pioneer MCA RIID gamma spectrometer

Messaggio da Matrix » 19/01/2022, 10:57

Experiment with brick wall shielding
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max56fe
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Re: Nuclear Pioneer MCA RIID gamma spectrometer

Messaggio da max56fe » 19/01/2022, 15:37

well thanks Matrix of the video, could you make the same video with the same source and the same shielding but with the 18x40 probe to evaluate the difference? thank you
max ..-.


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Matrix
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Re: Nuclear Pioneer MCA RIID gamma spectrometer

Messaggio da Matrix » 19/01/2022, 17:49

currently I don't have 18x40 for test
The function is in beta and will work with large crystal volume like 51x51 or 63x63
For small crystals it will not give the same result for RIID.
Here I'm attaching same U-238 ore source spectrum behind the wall with 10x40 crystal, with and without the Compton hide. Radium lines are here,but RIID not have enough info for good detection due to crystal properties.

Immagine
IMG_5461.JPG
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max56fe
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Re: Nuclear Pioneer MCA RIID gamma spectrometer

Messaggio da max56fe » 19/01/2022, 18:03

Thanks Matrix, what you posted is more than enough to understand better, good job
max ..-.


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cipndale
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Re: Nuclear Pioneer MCA RIID gamma spectrometer

Messaggio da cipndale » 20/01/2022, 12:21

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19/01/2022, 10:57
Experiment with brick wall shielding
How much ore material there is and what is its concentration? I am a bit baffled by what are you trying to do. Compton scattering happens also inside the detector volume, as well as into the wall. So far the Compton suppression is said to be done via coincidence counting with an external detector (with respect to the counting one). Are you into some new, uncharted territory?



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Matrix
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Re: Nuclear Pioneer MCA RIID gamma spectrometer

Messaggio da Matrix » 20/01/2022, 13:19

Compton scattering that happens inside the detector is less critical. In the situation when you make spectrum inside the lab the source is usually prepared and separated and it's not an issue to identify.

But when you try to take spectrum or a natural source in situ when it shielded by walls/metal/soil then it may happen that RIID will not identify a strong source because the spectrum will be smashed - covered by the Compton from the surrounding environment. The dosimeter will show doserate elevation in that case, but spectrum has no typical lines. Try to put an pretty active source behind the wall or inside a tank of soil and compare the spectrum of the same source as it was without shielding.
My function helps to identify peaks in that situation, it made by software only and it's not perfect for all cases.
The U-238 sample I have is a hot (in my estimation) and has more that 2.5uCi or Ra-226. Here is the spectrum of it , cps and activity as tested without any shielding of the bottle with ore.
Immagine
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