Idea for MCA algorithm

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tim.hbn
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Idea for MCA algorithm

Post by tim.hbn » 01 Dec 2021, 10:52

Hi Everyone

What follows is an idea of mine for an algorithm which compensates for the horizontal movement of the peaks in a spectrum due to temperature changes. The problem is that this movement of peaks widens the FWHM of the peaks as the spectrum develops. It also, of course, makes isotope identification less accurate.

Obviously, the problem I have described above is not very significant for strong peaks which require only a short period of time to develop. However, if a spectrum contains a mixture of weak and strong peaks, this becomes a problem for all peaks in the spectrum if the weak peaks are allowed enough time to become visible.

The algorithm would record each individual pulse detected together with its height.

After the algorithm has gathered enough pulses at the beginning of the development of the spectrum, it would start using artificial intelligence to detect how the peaks in the spectrum have moved horizontally over time. It would then reallocate every past pulse to a different channel number in order to recreate the spectrum as if there had been no horizontal movement of the peaks. This would prevent the widening of the FWHM of the peaks.

Becquerel Monitor's "Stabilizer" feature is not as sophisticated as what I have described above and does not prevent the widening of the FWHM of the peaks as the spectrum develops.

In a better version of the algorithm, the artificial intelligence would refer to patterns in known gamma spectra to see if it can recognize those patterns in the received pulses and then perform a corresponding calibration of the pulses. This extra task may be somewhat more difficult to achieve.

To be honest, I would actually be very surprised if no one has thought of this idea before. Does anyone here know if what I have described above has actually been implemented in any existing MCA software?

Kind regards

Tim

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Sesselmann
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Re: Idea for MCA algorithm

Post by Sesselmann » 01 Dec 2021, 19:11

Tim,

As you can imagine, a lot of brilliant minds have thought about this problem and various solutions have been tested. One solution was to introduce a tiny permanent source, either an isotope or a flashing led, inside the detector, this woukld produce a peak onto which the software could lock on.

Marek who wrote PRA did some experiments with a resistor and thermistor divider built into the detector and as long as the values are chosen carefully good results can be achieved, I like this because it's simple.

As you mention Becqmoni has a feature built in, it works, but produces somewhat strange non gaussian peaks.

We use real intelligence every day when we look at spectra and instantly recognise the shape, will AI do better an experienced scientist......who knows?

Steven

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GigaBecquerel
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Re: Idea for MCA algorithm

Post by GigaBecquerel » 01 Dec 2021, 20:55

How would the "Artificial Intelligence" know that the spectrum is shifting, and not decaying into something that's emitting gammas at a slightly lower energy?
In my experience software like this will always fail at some edge case, and those edge cases are way more common that you'd think!
https://i.imgur.com/thjTxRO.gifv

The best ways to stabilize the spectrum is using a temperature sensor to adjust the gain, or using an LED flasher to do so.

tim.hbn
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Re: Idea for MCA algorithm

Post by tim.hbn » 01 Dec 2021, 21:12

Hi Steven and Lucas

Thank you both very much for your informative replies.

I think you both make a good points.

Kind regards

Tim

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