Tag Archives: uSv

Polonium 210 Gamma – Found?

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Hello,

A week or two ago I set out to detect the infamous Polonium 210 gamma ray at 803.1 keV using a NaI(Tl) scintillation detector and a mere 3.7 kBq of Po210. This isn’t too hard, or so I have been told, to do with a HPGe or using my equipment and a significantly larger activity of Polonium. The problem is that only a few gammas will be emitted, only some will actually reach the detector, and of those only a tiny fraction will be detected! But… Who am I to listen? Lol I think that I found the gamma and it stands out in the spectrum, but I thought I would go a little further. This is not a formal paper (note my informal tone). I just thought that I would post a little more than a simple message.

Polonium 210 Gammas

Polonium 210 Gammas

My Environment

I have a temperature stabilized environment with a average temperature fluctuation of 0.8 c. from the mean over a period of six hours. The detector was allowed a full day to warm up and become stable. Calibration was performed several times and with several sources, including Co60 and Cs137. Redundant calibrations were performed and tested against each other to detect any changes.

The Test

A new (less than seven days old) small circular plastic disk containing approximately (+/- 20%) 3.7 kBq of Po210 was placed directly in front of the detection crystal at a distance of 1 cm. Between the source and the crystal, a thin Pyrex glass layer was placed. The test was allowed to run for six hours and then repeated without the Po 210 source to account for background. The background was removed from the sample spectrum to produce the results.

My Findings

A scientific result which can credibly called “true”, insomuch as any result is true”, requires at least five standard deviations from the mean of a set of data to rule out likely error. Given the very low amount of data logged and the generally entropic nature of the testing setup, such an outcome is unlikely. As a result, a positive declaration of the detection of Po210 gammas using the experiment as performed is unlikely.

A set of 60 data points was taken before and after background removal. These data sets were treated as a population set from which a simple population standard deviation was calculated, for both before and after background removal. Based upon calibration of the unit, the channel numberd 832 was the most likely channel to detect the gamma in. For both the origional data and the data with background removed, the channel, 832, displayed a clearly greater than other channels near it and for the set. For the raw data, channel 832 was 3.3636861676 deviations from the mean and with the background removed, the same channel was 3.2797495046 deviations from the mean. The variance between the data with and without background was 2.56%.

Sample Gross counts
________________________________
Channel     Count          Sigmas
828          17          -0.6757272749
829          16          -0.1812926775
830          21          -0.6757272749
831          28          0.8075765174
832          39          3.2797495046
833          19          -0.1812926775
834          25          0.0659246212
835          19          -0.6757272749
836          27          1.7964457123
.
Sample – Background
________________________________
Channel          Count          Sigmas
828          0          -0.7820334787
829          2          -0.9704752808
830          0          -0.0282662703
831          6          1.2908263444
832          16          3.3636861676
833          2          -0.4051498745
834          3          0.7255009381
835          0          -0.4051498745
836          10          1.1023845423

Coronal Mass Ejection – Detection

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On July 14, 2012 at 1424 EDT (1824 UTC, and 2:24PM local time) I believe that I detected a Coronal Mass Ejection, herein CME, an event where the sun bursts a massive amount of charged particles into space. These events are akin to solar flares, though not actually the same thing. The CME was detected by various organizations around the world and easily seen at SpaceWeather.com. At exatly 1824 UTC my detection units both noted a spike in high energy photon readings (gamma or X-ray from 10keV to 5 MeV).

Methods:

The Nekonome II Gamma Spectrometer, using a Radiation Sensors 6S6P1.5VD NaI(Tl) scintillation detector and a UCS30 MCA was run in multi-channel scaling mode, allowing for a gross count of detected photons for 60 second periods. The results were displayed as an x/y graph with the vertical y axis representing counts and the x axis representing time in increments of 60 seconds. A pancake Geiger Meuller detect with an LND7317 tube and an SE International Geiger counter was placed over other scintillation crystal. As a result, any photon radiation from the sun which impacted the crystal must also pass through the Geiger tube. Both units ran in concert for about an hour and the results were examined.

Coronal Mass Ejection

Coronal Mass Ejection

Results:

Both the output from Nekonome II and Geiger Graph software running on RadiationNetwork.com displayed a larger peak at 1824 UTC. This peak coincided with data from SpaceWeather.com indicating the strike of a CME at that same time. The most likely cause for the detection was a localized particle shower, yet the heavy lead shielding around the crystal detection ensure the energy detected must be above 500 keV and is more than likely above 1 MeV in energy. Without a high range gamma spectrometer, there is not conclusive proof of this find, but very probable data.

From Geiger Graph and the Geiger counter
68 7/14/12 02:21 PM 43 2,262 33 38.295861 -77.491647 59
69 7/14/12 02:22 PM 40 2,302 33 38.295861 -77.491647 59
70 7/14/12 02:23 PM 31 2,333 33 38.295861 -77.491647 59
71 7/14/12 02:24 PM 59 2,392 33 38.295861 -77.491647 59 < - Note the elevated reading.
72 7/14/12 02:25 PM 35 2,427 33 38.295861 -77.491647 59
73 7/14/12 02:26 PM 36 2,463 33 38.295861 -77.491647 59
74 7/14/12 02:27 PM 40 2,503 33 38.295861 -77.491647 59

From Nekonome II (UCS30)
60: 130 | 130 | 126 | 145 | 114 | 150 | 128 | 145 | 139 | 142 |
70: 169 | 129 | 115 | 127 | 150 | 153 | 140 | 145 | 146 | 150 | < - Note the elevated reading at minute 70 (minute 70 is 1824 UTC)
80: 134 | 161 | 125 | 137 | 127 | 135 | 132 | 158 | 139 | 128 |

Nekonome II:
_______________________________________________________________
mean 138.953
median 139. (8 occurrences)
s.d. 12.0346
minimum 109. (element 24)
maximum 169. (element 70)
Total 17,786

169 – 138.953 = 30.047 / 12.0346 = 2.5 StdDiv

Geiger Graph:
_______________________________________________________________
mean 34.0816
median 34. (10 occurrences)
s.d. 5.55697
minimum 21. (element 56)
maximum 59. (element 38)
Total 3340

59 – 34.0816 = 24.9184 / 5.55697 = 4.5 StdDiv

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.