Tag Archives: counter

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 Fiesta® Ware – Happy Cinco de Mayo!!!

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Fiesta® Ware – Cinco de Mayo!!!

It’s the fifth of may and everyone is celebrating the French receiving some sort of “beat down” by the Mexicans. Sounds like a party, but why not make it a Fiesta!?

I thought it a good time to find and buy a Fiesta® Ware plate of my very own.

Fredericksburg Virginia, close to me, has dozens of antique shops. Most antique shops I have visited in the United States are literally full of hundreds of pieces of uranium glassware and uranium ceramics.

How much uranium is in one of my local stores? Let’s do some “ball park” guess work. =)
I have read that glazes for (this is a touch anecdotal) ceramics, like Fiesta® Ware contained about 10-12% uranium by mass, while depression glassware contains about 2%. If I suppose that a normal antique shop has about five pieces of Fiesta® Ware at 50g’s of glaze each and 50 pieces of depression glassware at about 150grams each… we would get:

5pieces (50g)0.12 + 50 pieces(150g)0.02 = 180g of uranium =) That’s 6.3 ounces…

Of course, this is merely a guess.

Anyhow, the piece I purchased (for a mere $20) is quit lovely, behind lead, and old too. The gamma spectrum I detected showed a much greater U-235 peak at 185.71 keV and 143.76 keV than I would have expected for natural uranium. Also, the equilibrium of Pa-234m is low but growing faster than my DU marbles… I would have to call this processed natural uranium oxide. I would guess that my does is somewhere between 2-8 mR/hr at contact, which is why I keep the plate far away and behind lead. =)

Data from: http://pbadupws.nrc.gov/docs/ML0829/ML082910862.pdf
and http://www.orau.org/ptp/collection/consumer%20products/fiesta.htm

Nuclear Alchemy: The Transmutation of one Element into Another

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Nuclear Alchemy: The Transmutation of one Element into Another

I bombard aluminum 27 (13 protons and 14 neutrons), the stable type we have all come to know and love, with energetic alpha particles (two protons and two neutrons) at an energy of 5.3042 MeV! (MeV means Millions of Electron Volts). Most of the alpha particles would have bounced off of the aluminum without joining… but some would. Those lucky alpha particles bonded with the nucleus of the aluminum 27 to produce a new element: phosphorus 30! (15 protons and 15 neutrons). The reaction emits one spare neutron with way too much energy! =(

The phosphorus 30 has a short half-life of a mere 2.49 minutes, decaying into stable silicon 30 (14 protons and 16 neutrons) via beta+ decay (a positron). The position emitted is an Anti-Electon! That’s right, anti-matter. The quick little positron has an average energy of about 1438 keV (a max of 3203.3!!!). The position lasts only a short time before slamming into a normal electron and annihilating with an energy of 1022 keV, expressed as two gamma rays, each with 511 keV of energy. It is these emissions which I detect, using gamma spectroscopy. A Geiger counter would never be able to give me these results.

Al-27 + He-4 → P-30 + N
(e+) + e → y

I had calculated the energy of the reaction many times, but each calculation was a little wrong. I asked a very smart physicist for some help and he gave me a formula for figuring it out, but my math and his still didn’t add up…

Here is what I used for my determination:
I took the mass of an atom of P-30
(4.97802×10^-26 kg), call it M, and the mass of a single Neutron (1.67493×10^-27 kg), call it N, and the energy of the alpha particle which slammed into the aluminum (which was not at rest, but probably not doing too much whilst in its lattice, 5304.2 keV = 8.498×10^-13 joules, call it E. Also, let Em = momentum of P-30 atom after ejection of neutron, En momentum of neutron after being ejected: Em = (N/(M+N))E =(1.67493×10^-27 kg / (4.97802×10^-26 kg+1.67493×10^-27 kg)) 8.498×10^-13 j = 2.76620721*10^-14 joules = 172.6531 keV En = (M/(M+N))E = (4.97802×10^-26 kg /(4.97802×10^-26 kg+1.67493×10^-27 kg)^-1) 8.498×10^-13 j =8.22137928×10^-13 joules = 5.131382 meV

But… his numbers didn’t match (he thought the neutron would be 2.574 MeV and the phosphorus 30 would be 0.086 Mev.

Either way… OMG! That’s too much neutron flux for me in my tiny home lab. =)

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.