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Fukushima Soil Sample

Posted: 29 Aug 2020, 22:08
by GigaBecquerel
Hello!

I got a sample of fukushima soil from Luuk and took a few spectra with different detectors.
it has very visible ¹³⁴Cs lines, but of course the ¹³⁷Cs is dominant, with above 30 cps!
Sadly ¹⁵²Eu and others are below my detection threshold.

Here's a spectrum with my LaBr3:Ce detector, showing more of the low energy peaks, including the very strong Ba x-rays
LaBr labeled.PNG
LaBr labeled.PNG (54.37 KiB) Viewed 1455 times
fukushima4.PNG
fukushima4.PNG (59.75 KiB) Viewed 1455 times
Here's the same spectrum with my HPGe. It shows more of the higher energy peaks, but is blind to the x-rays:
fukushima1.PNG
fukushima1.PNG (58.26 KiB) Viewed 1455 times
fukushima2.PNG
fukushima2.PNG (66.09 KiB) Viewed 1455 times
¹³⁴Cs has two pairs of peaks very closely spaced together, only separated by ~5 keV.
Those lines are well divisible on the HPGe and give a nice look into the resolution.
HPGe closeup.PNG
HPGe closeup.PNG (60.72 KiB) Viewed 1455 times
Thanks to its short half life of about 2 years the ¹³⁴Cs is decaying at a visible rate, Luuk made a report about this soil a few years back and the peaks are way stronger!
https://www.gammaspectacular.com/phpBB3 ... p?f=5&t=27

All in all it is a very nice sample, both in the visible and ionizing ranges of the electromagnetic spectrum, with some real historic value behind it!
photo_2020-08-29_14-02-10.jpg
photo_2020-08-29_14-02-07.jpg
Best regards,
Lukas

Re: Fukushima Soil Sample

Posted: 30 Aug 2020, 07:50
by Go-Figure
Welcome to the club Lukas,
i couldn't identify the first Cs134 peak in my sample with my 2''x2'' NaI(Tl), I had to do it indirectly.

An HPGe solves a lot of problems, the result is really nice.

Massimo

Re: Fukushima Soil Sample

Posted: 30 Aug 2020, 17:11
by GigaBecquerel
Hello Massimo,

Thank you, now I'm finally one of the cool kids! ;-)
What do you mean by indirectly identifying the peak?

Lukas

Re: Fukushima Soil Sample

Posted: 30 Aug 2020, 17:16
by luuk
Hi Lukas,
Great results with your new LaBr3 detector, it works just perfect!
But my hart opens when I see the HpGe spectra, brings me back to old days a long time ago
when I build and tested them for Harshaw.
Luuk

Re: Fukushima Soil Sample

Posted: 30 Aug 2020, 18:42
by GigaBecquerel
Hi Luuk,

I am really happy how the LaBr turned out!
It really is a good alternative to the HPGe and I'll safe a lot of money on LN2 in the future.
Don't worry, I'll still supply lots of HPGe spectra as I find more interesting samples ;-)

Lukas

Re: Fukushima Soil Sample

Posted: 03 Sep 2020, 08:57
by Go-Figure
GigaBecquerel wrote:
30 Aug 2020, 17:11
Hello Massimo,

Thank you, now I'm finally one of the cool kids! ;-)
What do you mean by indirectly identifying the peak?

Lukas
I meant this https://www.gammaspectacular.com/phpBB3 ... ?f=5&t=517

Re: Fukushima Soil Sample

Posted: 03 Sep 2020, 21:12
by GigaBecquerel
Oh, I see!
That's a very interesting technique I have not thought about before.

I am aware that those are two very different things, but your "cutting out peaks" reminded me of this fun experiment:
http://www.nuclearphysicslab.com/npl/np ... incidence/