Wednesday, June 1, 2011

More Radiation Stuff - Playing with Lightning

I have been looking for neat things online by people using various radiation detectors for all the new radiation detector owners. This link to Whats Hot and Whats Not is a great source for guys getting freaked out with the readings they find on their new radiation detectors.

The first video you can see the sparks cause by alpha particles. One of the sources used is a smoke detector ionizer.

This video is a pretty neat demonstration of x-rays. While they are created differently, x-rays are produced by free electrons like the beta particles and similar to gamma rays.

Geiger counters are designed to test for alpha particles and gamma rays. So if you are looking for Cesium 137 or iodine 131, the Geiger counter will pick up the gamma part of the decay. Strontium 90 though has very high beta radiation and very small gamma radiation. When I posted More on Radiation - When to be Worried I gave some numbers that many may think are way too high. They really are not, but radiation testing requires a lot of practice and formulas to get solid results. The natural radiation in your body from Potassium 40 will produce the 60 counts per kilogram per second if you can properly test and calculate. Beta particles don't travel very far and most detectors you are liable to purchase will be the Geiger counters. So you will only be testing a fairly small amount of gamma radiation that can travel to the detector and be measured. So instead of 60 cps you may only register 10 to 20 counts per minute.

I was very specific about sticking to counts or pops and not the energy, Sieverts, because that is pretty tricky to measure accurately. You can establish a baseline which can be of some use, but other than some counts versus a bunch more counts, not a lot without specialized equipment. If you are into testing your food for safety, it is pretty easy to compare something you know is safe against something suspect. But you are looking for something often with the wrong glasses.

Iodine 131 and Cesium 137 should be pretty easy with any counter. Both have enough average gamma energy to be detectable, but it is the difference that gives you the clue.

The limit per kilogram in food for Japan is 500 cps or Becquerel. If you are measuring meat, which is pretty dense, you would have a higher reading than measure say dried tea which is very light in comparison. That is when measuring gamma radiation which can travel through the denser meat. If you have a beta detector, like in the second video, you are more likely to measure more radiation in the tea than the meat because the tea is more likely to block less beta particles. So it will be pretty easy to think something good or bad and be totally wrong.

That is why I wrote the last post and this post, to get you to think. While I have been looking for good links from people that know what they are doing, I have been finding several by people that are getting pretty lost. One was by a pretty smart guy that noticed that when it rained his radiation readings went up. That can happen for several reasons that have nothing to do with Fukushima fallout.

First, there are many areas where the main source of background radiation is radon gas. In the rain the radon get a little more concentrated. The difference is tiny though. It may be 15 counts per minute before the rain and 17 while it is raining. That is perfectly normal

Second, if it was dry and dusty before the rain, it is likely that the dust will increase the readings a little as the rain washes it out of the air. Unless you see a pretty big jump in the count, three or more times higher, there is no big deal. Particulates like smoke or smog can increase the readings as well.

After the rain you will probably see a slight decrease in the background radiation. Small changes are perfectly normal. After you get familiar with your counter you will get a better feel for how much is a lot. Even then you are limited to counts, which could amount to very little harm and not energy which is what you want.

In the first video with the sparks, that was alpha particles. Alpha particle are pretty much harmless unless you eat them. Hardly any of the Fukushima fallout was alpha particle emitters, so your smoke detector is about the best source you can find to testing your counter for alpha particles.

This video is just for fun. Neutrons are around us too in small amounts but not a problem. But this shows in a small way what makes a nuclear power plant work.

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