Introduction and Rain Spectrum

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Go-Figure
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Introduction and Rain Spectrum

Post by Go-Figure » 04 May 2019, 22:57

Hello folks,
My name is Massimo and I am from Italy.
I am a mechanical engineer and I am quite new to gamme spectroscopy, I got my GS-2020 2"x 2" NaI Scintillation detector + GS-USB-PRO Driver only a couple of weeks ago so I am deep in the beginners zone.
I still have no shield, so all my measure so far are unshileded background subtraction. My (for now only) calibration source is Cs137 which leaves me prone to loss of accuracy at higher eneregy.
Having said all that I am aware I have plenty still to learn and to improve, so in case you spot something terribly terribly wrong (or even just slightly off) in my spectra don't shoot me. On the other hand I'll be grateful to anyone who would give me useful feedbacks, pointing out at mistakes and giving me the chance to get rid of them.

I like taking spectra of "nasty" stuff like uranium ores (I know there's far nastier than that), but aso to test weaker and more common objects, and actually I like to take long background measures, not only to subtract them from the spectrum of the sample of the day, but also to measure the differences between background themselves: different houses, different rooms of the same house, different outdoor, etc.

Ok, introducing yourself in a forum like without posting at least one spectrum would probably be "rude" so this is one of my latest ones. It's the day before yesterday rain. I collected the rain from my car body using paper towel and then I stuffed them into a few plastic containers. I will repeat the measure today or tomorrow (rain is forecated here) using plastic bags instead of plastic containers.
If I am not mistaken nearly all the expected peaks from Radon 222 progeny (basically Lead 214 and Bismuth 214) are visible (I removed the gaussian correlation which helps to identify some of them for a cleaner image).
Both the rain spectrum and the background spectrum subtracted from it are the result of a 3 hours measure.
The x-ray part is a bit mixed-up so I don't know if I can simply label it as the result of Lead 214, the mean value of the ROI is very close to 77 keV though.


Nice to meet you all.
Until next time.

Massimo

Image
Last edited by Go-Figure on 05 May 2019, 01:21, edited 1 time in total.

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pilgrim
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Re: Introduction and Rain Spectrum

Post by pilgrim » 05 May 2019, 00:27

Hi Massimo, welcome to the forum.
The only thing I could suggest you is to make this test collecting the first rain after a longer period of good weather, in order to have a greater concentration of radon in the paper towels.
This is an old test I made with an electrostatically charged balloon.
The resolution is awful but the spectrum is similar to the yours.
Ball Radon.png
Daniel, Italy

GEOelectronics
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Joined: 09 May 2019, 03:10
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Re: Introduction and Rain Spectrum

Post by GEOelectronics » 09 May 2019, 05:00

Hi Massimo. You mentioned having no lead shield, if there were a lead shield I would guess X-Rays from the stable lead in it causing the ~77 peak. This is common as the stable lead is being excited by random cosmic rays, emitting it's characteristic X-Ray into the probe. We solve that by a copper lining between the lead and the probe. We can get lead sheet material used for roofing work here in USA, it makes a great shield. Even old dead sealed lead-acid batteries will work to some extent as a cheap shield.

George Dowell


Go-Figure wrote:
04 May 2019, 22:57
Hello folks,
My name is Massimo and I am from Italy.
I am a mechanical engineer and I am quite new to gamme spectroscopy, I got my GS-2020 2"x 2" NaI Scintillation detector + GS-USB-PRO Driver only a couple of weeks ago so I am deep in the beginners zone.
I still have no shield, so all my measure so far are unshileded background subtraction. My (for now only) calibration source is Cs137 which leaves me prone to loss of accuracy at higher eneregy.
Having said all that I am aware I have plenty still to learn and to improve, so in case you spot something terribly terribly wrong (or even just slightly off) in my spectra don't shoot me. On the other hand I'll be grateful to anyone who would give me useful feedbacks, pointing out at mistakes and giving me the chance to get rid of them.

I like taking spectra of "nasty" stuff like uranium ores (I know there's far nastier than that), but aso to test weaker and more common objects, and actually I like to take long background measures, not only to subtract them from the spectrum of the sample of the day, but also to measure the differences between background themselves: different houses, different rooms of the same house, different outdoor, etc.

Ok, introducing yourself in a forum like without posting at least one spectrum would probably be "rude" so this is one of my latest ones. It's the day before yesterday rain. I collected the rain from my car body using paper towel and then I stuffed them into a few plastic containers. I will repeat the measure today or tomorrow (rain is forecated here) using plastic bags instead of plastic containers.
If I am not mistaken nearly all the expected peaks from Radon 222 progeny (basically Lead 214 and Bismuth 214) are visible (I removed the gaussian correlation which helps to identify some of them for a cleaner image).
Both the rain spectrum and the background spectrum subtracted from it are the result of a 3 hours measure.
The x-ray part is a bit mixed-up so I don't know if I can simply label it as the result of Lead 214, the mean value of the ROI is very close to 77 keV though.


Nice to meet you all.
Until next time.

Massimo

Image

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Go-Figure
Posts: 124
Joined: 04 May 2019, 22:24
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Re: Introduction and Rain Spectrum

Post by Go-Figure » 09 May 2019, 06:29

GEOelectronics wrote:
09 May 2019, 05:00
Hi Massimo. You mentioned having no lead shield, if there were a lead shield I would guess X-Rays from the stable lead in it causing the ~77 peak. This is common as the stable lead is being excited by random cosmic rays, emitting it's characteristic X-Ray into the probe. We solve that by a copper lining between the lead and the probe. We can get lead sheet material used for roofing work here in USA, it makes a great shield. Even old dead sealed lead-acid batteries will work to some extent as a cheap shield.

George Dowell
Hi George, nice to meet you.
I know there are several flourescence "peaks" from lead shield which can accour between 72 and 87 keV.
I am going to get myself a good lead shield soon, but this is one of the reasons why I am not so unhappy of not having one yet, because I would have probably dismissed the x-ray peak as simple flourescence, even having some copper in place I would have probably done that.

Btw I repeated the experiment on rain on Sunday. Pretty much the same spectrum (as expected) except for a little peak around 1500 keV which I can't yet explain.
This is not K40. With my usual calibration K40 shows around 1440-1445 keV (which is where the K40 peak in background was).
I will see if it materialises again in next tests.

Massimo
Attachments
Rainwater - ID - 4 Hours - BG Subtraction  - No Shield - 05-05-19 - Clean 0.05.png

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