Peter new here

[Peter-1]

Hello,

my name is Peter an I live in germany, Bayern. Before many years I have build a MCA with great effort. Now there is software for a sound card (for free) and so I started to build my small measuring station again. With a PMT from EMI 9656B and a 2" x 2" crystal are the first results are already quite satisfactory. I hope I can show you my last measurements with 250 gr KCl. Time was near 2 hrs.

2016_10_05-K40-2.png (86.22 KiB) Viewed 14232 times

I think the resolution is not so bad, I hope. Max energy is near 3000 keV
Kind regards
Peter

[Sesselmann]

Hello Peter,

Welcome to the forum and compliments on a nice spectrum of K40.

Yes we are lucky to have a choice of several quality software programs, many hours of coding kindly donated by the authors for free.

Steven

[Peter-1]

Hello Steven,

thank you for your answer. One question. I have all my measurements a high value in the range below 300keV , you can see it. Is this normal? Is this the software?

Peter

[Sesselmann]

Peter,

Yes, gamma background radiation counts fall off with increasing energy, I guess its just the world we live in, more atoms than molecules, more grains of sand than rocks, more rocks than boulders etc..

Steven

[ManuelDiaz]

Hallo Peter und wilkommen,
I also report from Germany (near Frankfurt area) :)

That K40 looks pretty neat! I suggest you to test PRA, it doesn't come with the fancy isotope identification , but I find it way easier to calibrate and use that Theremino once you get used to it! (Check Steven's video on youtube to learn how to!)

I suggest you to measure the background to see what you're getting, I'm in the process of solving some issues caused by my sound card, the stability of my USB ports, and ripple caused by my laptop power adapter as well, although the background looks quite OK from here.


Read you around!
Regards,
Manuel.

[Peter-1]

hello Manuel
I am at this time not on my PC. End of the Week i will Test the others Software.
Nice time
Peter

[Steve Dubyk]

Peter, welcome to the forum! What type of shielding are you using for your detector for measurement? It appears that the low end gamma may be due to background rad.

Steve

[Peter-1]

Hello Steve
I use at first 2cm Pb and next 8mm Cu. So I hope that the x-ray from the Pb is reduced. The distance from the Cristal and the Cu shielding is near 3cm.
Peter

[Steve Dubyk]

Peter, the shielding sounds good. If you look at the sample gamma spectra on Steven's web site, and a couple that I have attached, your spectrum looks good. However, I do not know the cause of the peaks below 300 keV. If you Google K-40 gamma spectrum and look at the pictures, they all look similar. Perhaps one of the more knowledgeable forum members know what these other peaks are from.

Steve

[Peter-1]

Hello Steve,

I am now back home and can also make the difference between the pure lead shield and the additional copper shield test.
What can I use to additional to the copper and how many mm must this be?
Peter