For staying safe you want high max range and energy-compensated dose response. No ultra cheap devices offer that, mine is the closest thing on the low end of price, but consider me biased... If anyone finds something to contradict that feel free to share, because it would be new info to me. Then there is the second hand market, for example mrad 113 is a good device that can sometimes be had for a reasonable price, probably there are other pro grade dosimeters on ebay for a reasonable price but I don't know follow that market closely.
Yes exactly, often a small energy compensated GM tube that is not very sensitive but can handle very high radiation levels is included in the same device as a pro detector with a fancy scintillator.
Oh I didn't realize that worked with home assistant. It's a little different than a Geiger tube, that device uses a PIN diode and reacts to radiation interactions with the diode itself. Accuracy isn't great for dose but probably decent enough. Sensitivity is very very low, takes a while to get a reading. In theory it should be able to handle high dose rate levels but the spec sheet says it only measures to 1 mSv/hr which is pretty low, I don't know why. Their radon sensor is a different sensor tech, and CO2 and such is standard stuff pretty easy to implement.
I really want to make one to sell but too many other projects. The last time I saw them for sale was through the UKRAA but they seem to be out of stock for a while. You might be able to cobble one together with ebay stuff and online guides but it would be a struggle. Sorry I don't have a better answer.
I am not aware of anything that can connect to home assistant like that. It is definitely missing from the market and something I would like to make eventually, but too many other projects to finish first.
I am not certain but this tube looks like an M4011 which typically measures up to 1 mSv/hr for a reference Cs-137 source. Pretty low maximum level, not suitable for emergencies.
tl;dr not useful. To make a long story short, max range is very important and these cheap tubes saturate easily, and they don't give energy-corrected dose rate. They also cannot do gamma spec (isotope identification), but that is not needed for a fallout scenario because fallout contains basically every isotope under the sun, no need to do any gamma spec. I have a very long detailed video about this topic on my youtube channel BetterGeiger
I gave a more detailed comment already, but price/performance is not a simple two axis thing. No consumer grade gamma spec device measures high dose rate which is needed for emergency use. Depending on the intended use case something lower cost than radiacode might make sense. For example the radiacode 110 ($400) has the same volume and type of scintillator, with very high sensitivity, as the better geiger S2L ($200), so both are good for handheld search for radioactive objects, but S2L has something like 30x higher maximum dose rate range which makes it more capable in emergencies, whereas the 110 has Bluetooth, mapping, and gamma spec... Which are very fun for hobbyist but have little true "practical" real world value. Different interests and different budgets would point people in different directions.
If you want to actually measure radon concentration quantitatively what you are describing is not the way. Typically devices simply measure alpha count rates coming from air, radon diffuses very effectively and no filtering or extra flow is necessary. Your technique would show "hey look there is a little bit of something radioactive here" but would be very difficult to turn into a concentration without a lot of extra complicated steps.
Cool project! My business is Better Geiger (www.bettergeiger.com), I design and sell radiation detectors. I just hope people keep in mind the capabilities and limitations of those simple Geiger tubes. Radon was mentioned on the project website, yes technically radon decay products are detectable but pracfically a Geiger tube is reacting only to terrestrial, cosmic, and other sources of radiation, not anything to do with radon. Measuring radon generally requires a dedicated device (I recommend ecosense, at least until I get around to designing one). You correctly noted that such a tube can't accurately measure dose, that's because it is not energy compensated, so usually such a tube has a count to dose conversion factor for Cs-137 that will cause major overestimation in realistic scenarios. Those cheap tubes of that type also saturates easily in radiation fields that are really hazardous, making it fairly useless in an emergency situation. That is the main distinguishing feature of my products, high range and energy compensated. I have put out some YouTube videos that go into more detail about radiation dose, fallout and how to reduce risks, etc. I've given a lot of thought to doing a project like this with a scintillator, but I don't think the demand is there for me to do it before a lot of other ideas I have... When a cheapo standalone Geiger tube device can be had for $50, my products with scintillator go for $150 or $200 for the very high sensitivity version, then for $250-600 there are a few gamma spec products like radiacode, raysid, and radview with varying other features that are fun for hobbyists (though be aware none of those go to high dose rate range). For hackability mine offers access to the digital and analog outputs, but it's not really made for gamma spec so the spectrum quality is poor, but it can be a fun way to play. I've given a lot of thought to something designed more for DIY people, but in my experience very few people actually want that, most just want plug and play, and the ones that do request it usually don't even follow through. I've only communicated with a couple people that actually pulled a spec from a better geiger. Maybe that would be different if I designed a device specifically for DIY, something really small with simple serial comm output or something like that... Maybe some day.
You are right max range is important for some applications, and most cheap Geiger counters saturate very easily (that two tube device you mentioned being a notable exception). Even still it is not great to refer to them as dosimeters because measuring dose with a low cost Geiger counter is risky at best. That's because they are calibrated to Cs-137. Some so-called energy-compensated Geiger tubes exist and give more accurate dose information, but they are not used in consumer-grade devices (or at least none that I've seen, and I own a ton and constantly study the market). Also Geiger tubes can pick up a lot of beta, and in that case it will dramatically overestimate dose because beta should be blocked in order to get an accurate dose reading, and none of the usual suspects do that. Even if beta is blocked, dose is often strongly overestimated due to the lack of energy-compensation I mentioned. That's one of the reasons I developed the Better Geiger S-1, to have an accurate and fool-proof high range dosimeter at a consumer-friendly price point ($149).
It is a myth that radon collects in "low points", concentrations are low and it diffuses as the molecules bounce around. However, as you said radon is entering into those areas primarily, which means it will naturally be higher in those areas. Secondly basements often have poor ventilation, which is not to say that the radon cannot otherwise escape, but ventilation can disperse it much more rapidly than diffusion.
I'm sorry to say that some of the sensor design details, including material and geometry, are not shared. That was a critical optimization process during the design phase (tricky balancing act between cost and performance) and I want to slow down any copy-cat devices. However in terms of performance I am pretty open and detailed about how the device actually behaves:
Another metric some people like is CPM/[uSv/hr] when exposed to Cs-137 (662 keV). That number is about 415, whereas cheapo Geigers can be as low as 10, and decent consumer-grade Geiger counters are usually around 120. This number gives a decent idea about relative X-ray/gamma sensitivity of those devices.
Thank you! Most people don't need one (and hopefully it stays that way) but I still think it's a fun and educational device. If nothing else it's a conversation piece. :)
Yes, and even if you have a high-end alpha detector, ingested radioactive material cannot be detected externally if it's only emitting alpha. One would need to take a blood sample or something like that and do more complicated tests.
Beta particles are basically energetic electrons flying around, yes, but for a Geiger counter to detect them they have to be quite energetic in order to penetrate the Geiger tube itself (detection occurs essentially inside the tube, in the gas)... So I doubt that static field is generating electrons anywhere near that energy needed to be detected by a Geiger tube.
I think the core of the explanation given is correct but some of the adjacent details need adjustment. The important part is:
"Clothes dryers are very effective at making statically charged surfaces. (Dryer sheets help.) So when radon and its temporary decay products are blown through the dryer, electrically-polarized molecules tend to be attracted to the charged surfaces"
What that commenter misses is that nearly all hobbyist grade detectors (Geiger tubes) are not sensitive to alpha but they are highly sensitive to beta and a little sensitivity to gamma. However, any thin solid will block beta, so they would need the Geiger tube to be very near the radiation emitting material to pick up the beta. In other words, if they're just waving the detector around they're probably just catching the gamma.
The radon in the air decays into various progeny, and by the time it reaches the dryer that will be to some extent in equilibrium, so several isotopes, including gamma emitters, will be present in the mix. Therefore I'm not surprised the detector reads a tiny bit of that.
Why it dissipates is probably not a decay thing but rather the accumulated material gradually diffusing away from the filter or whatever after the dryer is turned off and no longer actively accumulating radon.
This could be tested by putting a detector right next to the filter to see how much beta it picks up. I've basically done that with a home air filter:
That's with the detector I make and sell which is primarily sensitive to gamma, which is why I could register a reading through the plastic container, even a couple days after preparing the test. When I used a pancake style detector sensitive to alpha and beta, directly against the exposed filter, the detector reacted much more strongly... But the Better Geiger S-1 gives an accurate dose reading, the Geiger tube or pancake probe will dramatically overestimate dose in that scenario, which can cause undue concern... In reality it's pretty harmless levels of radiation. :)
Here's how I would approach it... Based on a given detector geometry you can imagine it has a detection efficiency as a function of distance from the detector. Now you can imagine the source traveling in a straight line such that it passes some minimum some distance from the detector and at some velocity. From that path there is an expected number of counts that the detector would receive on average from that source as a function of minimum distance. Using that function and the background count rate one can estimate how close the source path needs to be from the detector to reliably detect it. From this you can optimize the altitude and velocity of the detector traveling along the road. I hope this brief explanation makes some sense. The hardest part would be to decide what signal to noise ratio is acceptable. For vehicle mounted it would simpler because you can probably just fix the elevation and only focus on the velocity as a variable.
Unfortunately not yet. Right now I am struggling to keep up with demand but when I have some more units on hand I'll probably try to set up Amazon fulfillment in some countries in Europe.
I really don't follow this narrative. Yes it's hot and remote and it's a 1400 km road. All of those things are clear. It's still very easy to put sensitive detectors inside a vehicle and drive along the road. These are uncommon and fairly expensive devices but there are plenty of them around. If the source is on or near the road it will be found that way pretty easily.
Do you think animals can only move a meter per minute!??
First of all, this part is not necessarily common knowledge but serious health effects does not mean incapacitated, and in the case of radiation it usually means effects that come on in the days/weeks following exposure, at least for humans. Animals can have different radio-sensitivity.
Regardless of that, a critter could easily travel a few hundred meters or more in a matter of minutes!! The search area then grows enormously. Total game changer.
Yes, I recommend mine ;) ... the "Better Geiger S-1"
In the budget price range (~$150 and under) my detector, which uses a solid scintillator, and a traditional Geiger tube based device are really the only options worth considering.
The pros of my detector are high range (max 20 mSv/hr vs typically 1 mSv/hr for common Geiger tubes), roughly 3x higher X-ray/gamma sensitivity, and automatic energy-correction of dose rate for better accuracy in realistic scenarios. I also think the design is pretty robust and user-friendly, people seem to like it.
A traditional Geiger tube has some pros also. The only ones worth getting in the budget range, in my opinion, are the GQ GMC type (there are variants but most are basically the same). They are a little cheaper and they have more bells and whistles like data logging. Another pro is that they have higher beta sensitivity, but that's a con also. Antiques like uranium glass and fiestaware are primarily low energy beta emitters so my detector reacts very weakly but a Geiger tube reacts very strongly. That's a con also, though, because when measuring dose you should NOT measure beta, so it means traditional Geiger tubes dramatically overestimate dose rate when they are exposed to beta (a common mistake among beginners).
Just please don't buy any of the super cheap import detectors that have suddenly appeared on the market in the last year or so, they are all terrible.
At higher prices (~$400 and up) there are a lot of different options with pros and cons, it just depends what the intended applications of the detector are.
Radiation detection is my specialty. This source is Cs-137, few hundred mCi. It's easy to detect within a few seconds at distances of a few tens of meters or more with professional detection equipment if there is direct line of sight.
If it was knocked off the road, though, the question will be if it fell into a crack or other such place because then the radiation is somewhat shielded and it would take much more measuring time to identify it.
I suspect if a few passes with vehicle-mounted detectors don't find it then some drones with detectors traveling along the sides of the road would be a good next step. If a critter moved it or ate it then it's probably gone forever. At a distance of 1 meter the dose rate from that source is already not extremely hazardous unless a person were exposed for an extended period of time (like a full day or two). Getting closer, like putting it directly against your torso, would mean serious health effects in a matter of minutes.