Energy per Bin (Channel)

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Steven Sesselmann
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Energy per Bin (Channel)

Post by Steven Sesselmann » 30 Mar 2019, 21:45

Hi All,

I was testing a new 2" NaI(Tl) detector today, I recorded a 30 minute background spectrum with the detector sitting on my desk (see spectrum below in red). Represented in linear form it comes out as predicted with a little hump for K40 approximately in the middle and no significant stand out features. Obviously our histogram is showing the counts in each bin.
counts.png
Counts per bin
counts.png (52.8 KiB) Viewed 1057 times

Then I was wondering how it would look if we plotted energy per bin instead of counts per bin, so I calibrated the spectrum in PRA and exported the histogram to a spreadsheet where I simply multiplied the energy by the number of counts in each bin, and plotted it (see green spectrum below).

Immediately it is possible to see more detail and structure in the spectrum. Since this is a very simple calculation to do, I don't know why the programmers have not added this feature as a third option to the usual Lin and Log options.

In the spectrum below we can see K40 stands out very prominently at 1460, we also see Ti208 at 583 and Pb212 at 238 etc...
energy.png
Energy per bin
energy.png (71.69 KiB) Viewed 1057 times
Below I also feature a Cs137 spectrum, represented both as counts and energy, as you can see the features change and the 662 peak becomes more prominent.
cs137.png
Cs137 Comparison
cs137.png (63.73 KiB) Viewed 1051 times
It's possible that this feature is common on other software and that I haven't seen it, but thought I would share it with you guys anyway.

Steven
Steven Sesselmann | Sydney | Australia | gammaspectacular.com | groundpotential.org | beejewel.com.au |

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Steven Sesselmann
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Re: Energy per Bin

Post by Steven Sesselmann » 31 Mar 2019, 14:11

Here is another comparison for Thorium..

The red line is your typical counts per channel, and the green line is energy deposited per channel.
Thorium.png
Thorium spectrum
Thorium.png (83.13 KiB) Viewed 1037 times
Steven
Steven Sesselmann | Sydney | Australia | gammaspectacular.com | groundpotential.org | beejewel.com.au |

Sebastien_billard
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Re: Energy per Bin

Post by Sebastien_billard » 01 Apr 2019, 04:26

Very interesting and it could be the base for a feature.

In Theremino MCA something approching is the "scale options" parameters which allows to dose fit the log scale as you wish.
Sébastien Billard, north of France
http://www.sebastien-billard.fr/tacticool/

25*25mm NaI detector

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Peter-1
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Re: Energy per Bin (Channel)

Post by Peter-1 » 02 Apr 2019, 19:53

Hello Steven,

i have a problem with your thorium spec. What are the last 3 peaks?
Here my spec from thoriumoxid.
Image
Peter

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Steven Sesselmann
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Re: Energy per Bin (Channel)

Post by Steven Sesselmann » 02 Apr 2019, 20:17

Peter,

If I am not mistaken, the last peak is Ti208 at 2614 keV, the second last peak is the Compton edge and the third last peak is the pair production escape peak (2614 - 511 = 2103 keV)

These are also visible in your spectrum, but not so obvious.

You have an extra peak at 1600 keV in your spectrum, which I think may be K40.

Be careful with Theremino because the rubbery calibration system can move peaks to wherever you want them.

Steven
Steven Sesselmann | Sydney | Australia | gammaspectacular.com | groundpotential.org | beejewel.com.au |

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Peter-1
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Re: Energy per Bin (Channel)

Post by Peter-1 » 03 Apr 2019, 08:04

Hello Steven,
I think my calibration is ok. I tested with Am241 Cs137 K40 Lu176 Ra226 Kr85 and Th
Here my last test with KCl -> K40
Image
Peter

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Steven Sesselmann
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Re: Energy per Bin (Channel)

Post by Steven Sesselmann » 03 Apr 2019, 10:43

Peter,

That's interesting, there must be something in your Thorium oxide at 1600 keV which is not in my Thorium mantle.

Steven
Steven Sesselmann | Sydney | Australia | gammaspectacular.com | groundpotential.org | beejewel.com.au |

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Peter-1
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Re: Energy per Bin (Channel)

Post by Peter-1 » 04 Apr 2019, 19:57

Hello Steven,

I have a mantle like this here.
Image

and as you can see, its the same spec with a peak at ~1600 keV. Ac228 ???
Image

Peter

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Steven Sesselmann
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Re: Energy per Bin (Channel)

Post by Steven Sesselmann » 04 Apr 2019, 20:46

Peter,

Thanks, just as you were posting this I was recording a spectrum with the latest version of PRA.

On the screen clipping I have marked as many peaks as I could identify.

The peak at 1630 is now showing on my spectrum, I have identified it as Ac228, I also have a little peak at 3025 keV which can't identify.

Steven
Th232_gamma_spectrum.png
Thorium Gamma Spectrum
Th232_gamma_spectrum.png (53.44 KiB) Viewed 922 times
Steven Sesselmann | Sydney | Australia | gammaspectacular.com | groundpotential.org | beejewel.com.au |

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