I journey to Fredericksburg VA to find uranium glassware to buy!
Tag Archives: geiger
Where to buy isotopes:
Where to find lists of gamma energies:
Where to get a detector
Where to get an MCA
Where to get uranium!!! (how could you live without it?)
Equations (simplified for quick and dirty use!!!)
2 * (E keV)^2
___________________ = Compton Edge
511 keV + 2(E keV)
2 * (E keV)^2
E keV – ________________ = Back Scatter peak
511 keV + 2(E keV)
Best source for calibration: Cs137
Best detecttor type: NaI(Tl) 1″ or greater!
Best free MCA software: PRA 8
Tom’s Isotope Tables!!!
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)
Iodine -125 Electron Capture
Gamma – 35.49 keV 6.60 %
X-Ray – 27.47 keV 75.7 %
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)
A great place to find data on isotopes:
*** 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
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)
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:
And Natural Uranium & progeny.
Please visit my website for a short explanation of the basics of radiation!
Spectrum Techniques (Where I get my sources and Spectrometry equipment)
GeigerCounters.com (Where I get my Geiger counters)
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