Chernobyl Contamination in Italian Alps Soil Extended – 30 Day Gamma Spectrum

[Go-Figure]

Hello there,

First of all, is the thread title correct, or should it be “Piemonte Alps’s Soil”?

A few days ago I finished my longest measurement so far.

Since Ciro (Cicastol) very kindly shared this Italian alps soil sample with me I already tested it twice.
The first time it was a 36 hour run: a 12 hour background and 24 hours actually testing the sample, and the result was pretty messy. https://www.gammaspectacular.com/phpBB3 ... ?f=5&t=667

Then I extended the acquisition time to 24 hours background + 120 (5 days) sample adding some shield as well, and the result improved. https://www.gammaspectacular.com/phpBB3 ... ?f=5&t=738

In October I decided to give it another go, extending to 360 hours (15 days) background + 360 hours (15 days) sample.

Actually the experiment lasted for 40 days, because in the middle of it I had some technical issues with my PC, so I had to shut everything down, luckily I saved every few days so I didn’t have to start again from scratch. Also, this was a confirmation that you can stop the measurement and shut down the PC, and when you load the file again the software will load its calibration setting as well, so you can resume the acquisition. Of course if in the meantime there’s been a significant change in the temperature of the room you’ll be prone to thermal drift, so I wouldn’t advise to start a measurement in July and resume it in January, but a part from that you can tell from the result it worked just fine.

You can read about the usual preliminary stuff (Geiger counter and PDS early results) in the posts linked above, so I’ll go straight to “beef” here.
The shielding for this measurement was 5 mm of plastic, 1 mm of copper, 8 mm of pewter and 13-15 mm of lead, or what I call my Version 2-2.

The background was reduced from about 255 CPS to roughly 60 CPS. Interestingly this time the residual X-ray fluorescence peak was weaker than in my previous measurements with the same shield. It’s not the first time this happens, I remember once having a result where the fluorescence peak was completely missing. I’ve never quite understood why that happened.

02-Background - Stanza Fondo - 360 Hours - Counts x Bin - Shield V2-2 - 0.035 Gauss - 19_23-10+03_11-11+24_29-11 - 20.png (62.76 KiB) Viewed 5171 times

The extended acquisition time resulted in a way better result this time. I could clearly identify a lot of natural peaks, besides those from Cs137. As you can see the calibration held brilliantly during the 30 day measurement, even with the inconvenience described above.
The sample is extremely weak, from some reason this time I was able to only extract less than 6 CPS from it (2.35% of background) while in my last attempt it was 9 CPS. I should have checked the counts from the sample early on and adjust the geometry in order to maximize them, but unfortunately I only figured that out once I was toward the end of the acquisition.
In the energy per bin view you can see the Cs137 peak at 661.67 keV is actually the most prominent one.

The quantitative analysis recaps what mentioned above.

After this very long recording I will give my good old computer some vacation, while I look for some new interesting sample to test.
Until next time

Massimo

[cicastol]

Now it really stand up!
30 days integration should be taken as a new World record guiness :-)

[Go-Figure]

Now it really stand up!
30 days integration should be taken as a new World record guiness :-)

Yeah, but my PC didn't like it, I can tell you!