Summary From Testing the Accuracy of My Radex RD1212 Radiation Dector

(IF you wish to see detailed features of the Radex RD1212 click here.)
(To see my post  on what comes in the package & my pictures from the day it arrived click here )

When I first got my Radex RD1212,I did not understand that radiation is not stable. What I mean is that it fluctuates minute by minute when you are taking readings in the rage of .01 uSv/hr (1/100th of a micro serverts/hour).

A sudden reading fluctuation up to 0.30 uSv/hr for one reading during the first two days of owning the device caused some doubts. in general the highest reading for that area is 0.22 is uSv/hr.

After contacting to 2 other more experienced users I learned that such a fluctuation is quite normal, and could be consider small in some parts of the world. One of the contacts was at first thinking that I got a spike form natural minerals in that area. He stated that if I had  high levels of natural thorium/uranium/potassium, that can make the readings jump wildly. He suggested I test in multiple locations for an extended time.

I did as he suggested. I tested out the device by taking extended readings at three locations. I included the location that caused me to doubt the reliability of the device as location #3. I think with only 3 locations I was able to determine the device is stable. Let me know if you disagree.

The first location was stable and in a narrow range, completely opposite from what I expected. I was able to duplicate the same results 2 more times. I failed to record the average for December 12, but 0.09 uSv/h is a safe bet.

Location #1 - 41.045302,-85.264529 (Yellow Apartments)

December 11, 2013 - 180 reads, Minimum 0.06, Max 0.14, Avg 0.09

December 12, 2013 - 140 reads, Minimum 0.06, Max 0.14, Avg ?.??

December 15, 2013 - 180 reads, Minimum 0.06, Max 0.13, Avg 0.08

(Readings are in uSv/h)

For a full print out of results for each test click here:

http://fwradiation.blogspot.com/2013/12/radiation-levels-off-aboite-center-rd.html

I even have a single test of readings about 1 mile from location #1 that is very similar:

December 24, 2013 - 180 reads, minimum 0.06, Max 0.14, average 0.09

http://fwradiation.blogspot.com/2013/12/woodstream-park-on-woodstream-dr-aboite.html

Location #2 had a lower lowest reading that was 0.01 uSv/h below the lowest reading of  Location #1. It had a highest reading that was 0.02 uSv/h higher than the highest reading of location #1. Once again a rather stable set of readings.

Location #2 - 41.015069,-85.151838  (Willow Creek)

December 11, 2013 - 180 reads, Minimum 0.05, Max 0.14, Avg 0.10

December 13, 2013 - 180 reads, Minimum 0.07, Max 0.16, Avg 0.10

December 22, 2013 - 180 reads, Minimum 0.06, Max 0.15, Avg 0.09

(Readings are in uSv/h)

For a full print out of results for each test click here:

http://fwradiation.blogspot.com/2013/12/radiation-levels-at-willow-creek.html

Location #3 is by far the most interesting.  You will note that on December 9, 2013 I got a high reading or 0.030 uSv/h and that is why I contacted you for your opinion.  You will note the even without the December 09 reading this location has a noticeably higher and wider range.

Location #3  - 41.098952,-85.11396 (Buena Vista Drive)

December 08, 2013 - 18 reads, Minimum 0.09, Max 0.22,  Avg 0.12

December 09, 2013 - 39 Reads, Minimum 0.08, max 0.30, Avg 0.14

December 11, 2013 - 65 reads, Minimum 0.09, Max 0.19, Avg 0.13

December 12, 2013 - 118 reads, Minimum 0.08, Max 0.22, Avg 0.13

December 13, 2013 - 153 reads, Minimum 0.08, Max 0.20, Avg 0.13

December 16, 2013 - 160 reads, Minimum 0.07, max 0.19, avg  0.12

(Readings are in uSv/h)

http://fwradiation.blogspot.com/2013/12/radiation-levels-at-buena-vista-drive.html

I had one other instance where I got a spike up to 0.34 uSv/h at location #3.  I do not have that data as the device was not recoding it. That makes Location #3 the only location where I could duplicate such a spike over 0.22 uSv/h.

I think that the fact I was able to consistently get stable data in a narrower and lower range at two different locations shows that the erratic readings I get on the device are a result of something in the environment of Location #3.

In over 1700 readings I  was not able to duplicate the sudden spike up to 0.30 uSv/h at any other location than the one that shows the widest and highest readings, except for one time when I was not recording data and I got a spike up to 0.34 \ in that same location. Also I was unable to get a reading of over 0.16 uSv/h at any other location.

I will finish this post with a resonse from one of the other Geiger counter experts:
https://www.youtube.com/watch?v=0tOARezivxo

Interesting!  I would say that your hypothesis that the readings are environmental is correct. I took all three sets of numbers and ran them through a spread sheet with some math. Here is what I found:

Samples 1

Avg 0.0897222222
StdDiv 0.0180139783
Max n sigma 2.7910424318

Samples 2
Avg 0.0988703704
StdDiv 0.0170021785
Max n sigma 3.5953998248

Samples 3
Avg 0.1250699301
StdDiv 0.0256849156
Max n sigma 6.8106150984


Note: 1 & 2 did have at least one count each exceeding the normal rule-of-thumb 2 standard deviations, meaning that these were likely events above and beyond standard background. 3 had a quite a jump.

Without more sophisticated gear, we will likely never know the source, but if I had to guess, I would suspect sample 3 detected a muon shower or something like that. Environmental contamination is often pretty stable (the readings). Those jumps are likely cosmic in origin.

Still, a 6.81 standard deviations from the norm jump is higher than anything I have detected (in  terms of a spike, not the actual count). Last time I got something that high it was from a solar event. When such things occur, they and correlate them with solar activity.

if you have a spread sheet software, try this:


If Column A has the counts, then for each x in A,

Column  B =   if( A(x) - AVERAGE(A(0):A(n)) / STDEV(A(0)>2; A(x) - AVERAGE(A(0):A(n)) / STDEV(A(0); 0 )

Change A(x) to the cell number (e.g.  A53). A(0) means first cell and A(n) means last cell.


or, if this is easier:


Number of standard deviations =   count - Average / Standard Div.

Testing food with a Geiger counter / Can I use a Geiger counter to test food?

Can I use a Geiger counter to test food?

For practicable purposes the answer is no.

There is no Geiger counter out there that can reliably test for radiation in food. It is not a question of accuracy.

The problem is that it only takes a very low amount of radioactive contamination to be dangerous if consumed. The radioactivity of the food will almost always be masked by the normal background radiation (which is usually of a non harmful type).

Example:  If containment is .02 uSv/h and the background radiation is .09 uSv/h, the Geiger will detect contamination but you will not see a spike in readings (which will continue to show .09 uSv/h). It would be like looking for a drop of water in a pond.

The exception of course would be if the food was extremely radioactive. If your background environment for example, varies between .09 uSv/h and .14 uSv/h and the food sample consistently spikes it to .20 uSv/h, you know you have something you better get rid of fast.

The only way to reliably distinguish between low contamination and the normal background radiation is in a lab, where food is placed into a container that isolates it from any background interference. That is the only way.

Next comes the question of how much food. A single piece of food most likely will not give you an accurate reading if any at all. You will need a lot of food. This is because it is very possible that the radiation leaves the sample in such a direction as to miss the tube in your device. The bigger the sample, the better the chance of the device picking it up.

This principle is best explained in the video below. It clearly demonstrates why you cannot accurately measure food.:

Testing food with a Geiger counter overview 

Finally you must remember that a Geiger counter only recordes radiation. It does not tell you what type. Take a banana for example. Bananas naturally give off radiation within a small range of 0.10 uSv/h. Yet bananas however or not harmful at all because they give off potassium – 40, which your body eliminates once it reaches a certain level.

What type of Geeger Counter Am I using? (Radex Rd1212)

I decided to purchase a Radex RD1212. If you wish to see its detailed features click here .

My RD1212 device arrived on Saturday Dec 7th, after having ordered in the morning 2 days earlier. I placed a pen along side the top to give a better idea of what size a person should expect.

After unpacking the box looked as in the picture below.

 Everything was properly wrapped and a mini CD was inside the wrapping with the manual.

The contents of the box are displayed below. Once again I included a pen in the picture to better illustrate the size of the RD1212 unit. I never used the CD because I already downloaded the software from the website before my unit arrived.

The CD or website program is optional. You only need it if you wish to plot your readings on a global map and see what other users have plotted, or if you would like to take data readings and save them to a text or csv file. Personally, that is a feature that I like and use often.

If you are curious and want to look at some global measurements, you can currently download the software for free at this link - http://www.quartarad.com/index.php?option=com_content&view=article&id=153&Itemid=174 . You will probably find it quite interesting.

If you look closely,  you will see that the proper way to install the batteries is clearly shown.

The manual give a pretty good run down on the unit, but you need to visit the website as well to learn how to plot to the global map. visit here:

http://www.quartarad.com/index.php?option=com_content&view=article&id=153&Itemid=174 

 

Here is a somewhat dark picture of the unit with the backlight turned on. It can be easily turned off in the set up menu. for some reason this picture distorts the unit. it appears a bit wider adn la bt shorter in real life.

 For a better picture - click here.

To see it at the sellers Amazon site click here .

To see my Review click here .