How difficult is it to detect K40 using LaBr3(Ce)?

Post by **tim.hbn** » 22 Sep 2021, 00:10

Hi Everyone

As some of you know, LaBr3(Ce) has an inbuilt peak of 1436 keV. The peak for K40 is 1460 keV. This means that there is the possibility that it may be rather difficult to detact K40 using a LaBr3(Ce) spectometer. What do you think?

I know that I can subtract a background spectrum but I am thinking that the effectiveness of this will depend on the relative strengths of the 1436 keV peak and the 1460 keV K40 peak of the sample I am measuring. I don't really know how they compare with each other.

Lets say I have a 500g bag of Potassium Chloride. How difficult do you think it would be to detect the K40 in it using a LaBr3(Ce) spectometer?

What about the k40 in a banana?

Thank you very much

Kind regards

Tim

Post by **Rob Tayloe** » 22 Sep 2021, 01:10

Attached is an image of the spectrum of K-40 using a LaBr(Ce) detector. The K-40 spectrum is shown in black and the background is shown in blue. The LaBr(Ce) detector was made for me by Steven and is discussed elsewhere in this topic.

Screenshot 2021-09-21 110608.jpg

Post by **Rob Tayloe** » 22 Sep 2021, 01:14

Note: in the above figure, I do not think the energy (x_axis) is correct. I believe the data is just channel vs counts.

Also I used KCl as the source, about a kg if I recall. There would be very little activity from a banana.

Post by **tim.hbn** » 22 Sep 2021, 02:02

Hi Rob

Thank you very much indeed for your replies.

It seems that you have managed to obtain a pretty decent difference between the K40 and background so it looks as if the K40 in KCl can easily be detected by a LaBr(Ce) detector.

Do you know the dimensions of your LaBr(Ce) crystal? (excluding the aluminium housing and window)

Thank you very much

Kind regards

Tim

Post by **Rob Tayloe** » 22 Sep 2021, 02:57

Here is a link to the discussion in another thread regarding Steven's build of this detector and my initial testing and measurements when it arrived to me in the US.

viewtopic.php?f=14&t=882

Post by **Rob Tayloe** » 22 Sep 2021, 03:00

I should have also mentioned that I used PRA software with a new MCA from Steven for the K-40 and bkg spectra shown above. I got much better results with PRA (once used correctly) than I did using Thermino.

Post by **tim.hbn** » 22 Sep 2021, 03:36

Hi Rob

Thank you very much for this.

I have clicked on the link you provided and I found out that your detector is a GS-1010-LaBr3. I have looked up the specs for it and the dimensions of the crystal are 25.4 x 25.4 mm and I have found the crystal on the following page of the Ost Photonics website:

https://ost-photonics.com/products/scin ... ntillator/

Thank you very much indeed for all your help.

Kind regards

Tim

Post by **iRad** » 22 Sep 2021, 08:31

It's still possible to pick out the Cs134 peaks from Fukushima with LaBr3...

Post by **iRad** » 22 Sep 2021, 08:35

Here is LaBr3 2X2 detector with background in grey and 5 pounds of Kitty Litter in Green.

Post by **Sesselmann** » 22 Sep 2021, 10:02

Hi Guys,

I am going to build another 1" LaBr3 detector in a couple of weeks, shall make a point of doing a few tests with it before sending it out to the client.

Steven

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How difficult is it to detect K40 using LaBr3(Ce)?

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