Tag Archives: Cs-134

Cesium 137 Detected in my Rain! (Radioactive Rain Detected)

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As you all know, I have always maintained that there is Fukushima fallout in the rain… but that the levels (even if they are unsafe) are too low for a Geiger counter to detect.

My sensitive Gamma Spectrometer has now (I believe) detected Cs137 in a rain water collection bucket which concentrates, or so it seems, the Cs137.

Most of the radiation detected by Geiger counters from rain is from Radon Washout, a processes whereby radon in the air (decays from natural uranium around the world) is “washed” out and falls to the ground in the rain. The decay chain is sudden and very quick, providing a few hours of potent readings before falling to background.

Inspector (regular or EXP) Sensitivity to Iodine 125:

0.02 µCi = 740Bq = 44,400Bq/60seconds
(At contact for I-125)

http://seintl.com/products/inspectorplusEXP.html

Iodine -125 Electron Capture
Gamma – 35.49 keV 6.60 %
X-Ray – 27.47 keV 75.7 %

http://ie.lbl.gov/toi/nuclide.asp?iZA=530125

Best energy range for detection by LND7317 probe:
10 keV = 100 keV (max)

The range where detector efficency falls rapidly (Cs137 is also in this range):
100 keV = 1000 keV (declining)

http://seintl.com/images/InspEnResponseC137_large.jpg

A great place to find data on isotopes:
http://ie.lbl.gov/toi/

*** Update! ****

I have calculated the activity:

My original calibrated Cs137 source (cal. vs. NIST tracible source, source ID SRS:80899-854, at 95% accuracy) was 3737 Bq.

I accounted for decay of the source:
3737*e^-((ln(2)/10979)*173) = 3696.4059560683608390980241545539265887454856828520474 Bq
=3696 Bq

For an ROI of the same size for both calibrated sample and rain water sample, I ran tests and determined counts per second:

Calibrated Source 91.2633 c/s
Rain Water Sample: 0.01439814814814814814814814814815 c/s

Now, I divided the detected calibrated sample c/s into the expected c/s to determine ratio of emission vs detection for the energies around 661.66 keV. (3696Bq * 0.851 [intensity for gamma from Ba137m])/2 = 1572.648. The division by two is because I entirely detected one side of the thin sample disk. so… 91.2633 / 1572.648 = 0.05803161292291727074335769987944

My detector is only about 5.8% efficient for such energies. (lower than my 12% “ball park by half”)

Now, merely divide the counted detection from rain by the efficiency and you have about the correct result.
(311counts/21600) /0.05803142216185694446564011781403 =

=0.01439814814814814814814814814815 / 0.05803142216185694446564011781403 = 0.24810951742643665986093914169915

Or 0.248 Bq/liter

(that is zero point two four eight Becquerels per liter)

Thoughts?

Nuclear Isotope Identification – Why Is something Radioactive?

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Radioactive materials are easy to detect with a Geiger counter, but cannot be identified with a Geiger counter. You need an isotope detector.

One of the most widely used isotope detectors is a Gamma Scintillation Spectrometer. In this video I explain how Gamma Spectrometers work. I also show you actual real-time capture of gamma spectra from several sources:
Cs-137
Cs-134
Eu-152
Am-241
Np-237
And Natural Uranium & progeny.

Please visit my website for a short explanation of the basics of radiation!

What is Radiation?

Spectrum Techniques (Where I get my sources and Spectrometry equipment)
http://SpectrumTechniques.com/ucs30_system.htm

GeigerCounters.com (Where I get my Geiger counters)
http://GeigerCounters.com

Radioactive Rain – April 21, 2012, Virginia

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I tested my rain again and found radon progeny once more.

It should be somewhat obvious by now, given the occurring, what the source of all of this.

Radioactive Rain – Radon Washout Found!

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Here is the short 3 minute version of the same video with only the results. =)

Geiger Counter vs. Scintillator

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Geiger counters are an indispensable tool for any scientist, professional or amateur (like me). The Geiger counter can detect radiation quickly and effectively. They are also relatively cheap, ranging from a few hundred to a few thousand dollars (most are under $1,000). Geiger counters have varying abilities and detect different particles and energy levels of those particles with differing levels of efficiency. By far, beta radiation is detected the best with many tubes detecting 2 to 4 out of ten particles which hit them. Alpha radiation is a bit lower, with many tubes totally blind to them and those which are not only detecting 5 to 10 particles per every 100. Gamma and X-ray radiation is the lowest for Geiger counters, where often between 1 and 3 photons are detected per 100.

Pros — Cheap, easy to use, portable, can detect alpha, beta, gamma, and x-ray.

Cons — Cannot determine isotope (fact), cannot determine energies, very low gamma and x-ray efficiency.

Scintillation counters are the tools of the professional nuclear scientist. Scintillation counters exist for gamma, x-ray, beta, and alpha radiation (a specific unit for each). When used with a multi channel spectrum analyzer, the counter can identify isotopes by their energies. Some Gamma spectrometers can even be used for complex gamma recoil analysis (mossbaur spectroscopy) which aid in determining the molecular bonds of various atoms, such as iron. Crystal sicntillators may cost a few hundred to a few thousand dollars, while a multi channel spectrum analyzer to attach to one is at least a few thousand more. This means an entry level lab-grade unit (like mine) will set you back about $5000. Very powerful soil state units, like those used at universities, can be well beyond $10,000 and even as much as a million dollars. A good High Purity Germanium (HPGe) is at least $10k. These detectors may be used without a multi channel spectrum analyzer, but they only count at that point. Hobbyists have created multi channel spectrum analyzer’s for under 1,000 dollars.

Pros — Can identify isotopes, measures energies, very sensitive to gamma rays (for gamma sicntillators), can probe hyperfine molecular bonds.

Cons — Expensive ($1000 and up), complex, requires extensive skill (physics), portable units are often very expensive.

Links:

Great MCA+Scintillator for entry lab-grade use. This is what I use:
http://www.spectrumtechniques.com/ucs30_system.htm

Small and portable scintillation devices (mega pricy)
http://www.laurussystems.com/IsotopeID.htm

A really great Geiger counter (Inspector EXP+)
http://geigercounters.com/EXP2.htm

Probably the best Scintillation video ever made
www.youtube.com/watch?v=h0dF2FUo5WU

What’s in your rain?

I detect the potassium in a single banana… GM can’t do this. =)
http://www.youtube.com/watch?v=a_SJH7VNAE0