Is Your Geiger Counter Lying to You? Understanding the Limitations of Your Geiger Counter
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- Опубликовано: 27 авг 2024
- With the proliferation of inexpensive Geiger counters, many less experienced users are unaware of the strengths and weaknesses of their instrument. This video discusses the proper use of the Geiger counter and its significant limitations, especially regarding detection efficiency and measuring dose rates. The Geiger counter is also compared to other technologies, such as scintillation detectors.
Part 1: A Popular History of the Geiger Counter [0:20]
Part 2: When is Your Geiger Counter Telling the Truth? [3:25]
Part 3: When is Your Geiger Counter is Lying? [8:25]
Part 4: The Do's and Don'ts of Geiger Counters [29:14]
* A note on average, U.S. background radiation [29:07]: The figure shown, 0.32 µSv/h, includes the impact of Radon and its decay products. These are usually negligible outdoors and the dose cannot be directly measured by a typical survey meter. A more realistic figure for outdoor, background radiation would be 0.06 µSv/hr (0.006 mrem/hr). Thanks to Dr. Ross Kleinschmidt (Environmental Health Physicist) and Kai Kaletsch (Environmental Instruments Canada) for this clarification.
Thank you so much for this! As a nuclear hobbyist with a vast, radioactive collection, these methods and units are overlooked by so many people, and many of them just don't know and/or care to take this into consideration! So many people that use G-M counters will use a dose unit to measure anything that's radioactive, rather than using CPM or CPS. I mostly use my SEI Inspector USB (v. 2.13), and I only use CPM or CPS. When it's gamma only, I measure it with a tin or brass filter, or I use my CD V-700, since those utilize energy-compensated probes. Also, detector geometry is very important, too. These new and cheap G-M counters usually only use dose units, making them inaccurate at the get-go! A good ol' CD V-700 G-M counter will detect beta and measure gamma properly, if used correctly. I also use gamma ray spectrometers, since those can identify radionuclides, and their energies. This was an excellent and comprehensive video! Everyone who uses a G-M counter, or that's considering to get a G-M counter, should watch this video! Thank you very much! Great job!
Awesome info. I got my first Geiger counter as part of a surplused CD-V-777 kit decades ago, and later a more modern digital type, and now have a Csl(Tl) scintillator-based Radiacode. I'd previously suspected that the scintillator's lower reported dose rate, despite far higher CPM readings than my GM-based meters were the result of its ability to differentiate energy levels. Always love learning new things!
Great video, shows very well the mistakes that most beginners make.
One thing to mention though, scintillation counters also have an uneven energy response if just using raw CPM. Most modern scintillation counters like the BetterGeiger or Radiacode will measure the keV of each pulse and accurately(ish) determine uSv/h, so that CPM ≠ uSv/h on these devices. However there are some scintillation devices that don't have automatic energy compensation built in though. Take for example a Ludlum 44-2 hooked up to a Ludlum model 3, this meter does not have the correct electronics for energy compensation, and will have the same issue geiger counter tubes do with uneven energy responses.
Also at 25:38, those filters do accurately energy compensate the tube, at least for radiation coming from the direction of the filter. Pretty much all energy compensated tubes can be assumed to read accurately within their stated energy range. The issue only lies within non energy compensated GM tubes, and non energy compensated scintillation detectors.
Great information although for most people this will just fly over their heads. Like you said it’s better to have something than nothing. Agreed, what most of us will use them for is for urban prospecting and the like.
Just the video i needed to help me with my first Geiger counter and scintillator device!
Thorough without droning on. Thank you
The video is great! Thank you for making it! The irony here is that you are making video to educate the public on the subject of Geiger Counters, and they went ahead and comment on it, showing again their complete ignorance, even on the very points this video explains.
Very informative!
At 2:10, the first item in the list is not a Geiger counter, it is an electric guitar effects box, and the second item is an EMF meter, not a Geiger counter! XD Great video overall though! This should be required viewing for anyone before purchasing their first Geiger counter!
There are also ion-chamber survey meters.
Great video! Thanks for the breakdown.
What are your thoughts on the Radiacode 102 and 103 and its compensation. I use both of those. Do they provide a more accurate uSv/h representation? - Excellent presentation! ❤
Definitely more accurate dose measurement than a GM counter, of course. Their reputation is well deserved. I am not sure how they compare to the Better Geiger S-1.
Awesome video!! Thank you
Very informative and well produced video! I really enjoyed it. Question about the thoriated welding rods, how did you break them up? I also have some rods and they are bothersome to store and display due to their shape. I also wanted to break them into shorter pieces but ran into warnings about creating dangerous fine particles in the process. What method would you reccommend? Thanks!
Thank you! The rods were so thin and brittle I was able to break them cleanly by hand. I never saw any dust. I think the warning may apply more to the welding process when the rods burn. But out of concern you can try breaking them inside a sealed plastic bag and removing the pieces carefully.
Have you tested BOSEAN FS5000 with J321 tube ? Some are claiming it is the best unit in its low price range. Measues up to 5 rads/hr
I have not tested it. It's only $40! Boasts an unusually high range which is good for safety applications, but not for finding low level contamination. The problem with all Geiger based dosimeters, as I explain in the video, is that they are only accurate at one energy level (in this case, Co-60). www.aliexpress.us/item/3256805120911864.html?gatewayAdapt=glo2usa4itemAdapt
@@kinetoscopemicroproduction6418 Ty...so the BOSEANFS5000 would not be useful if there was a nuke attack or meltdown at a nuke plant or a dirty bomb attack ? It would not measure gamma rays to alert the owner of danger ?
@@davehimlin2374 I would rather have one than nothing at all. It will certainly alert you to high gamma (and beta). But the gamma dose rate measurement would probably not be accurate since every pulse (gamma or beta) would be assigned the same energy value. The one nice feature, though, is that has a high saturation. Most units saturate well below 1 rad/hr.
It's rather rare event if a gamma ray interacts with the gas. It interacts mostly with the metallic tube through photoelectric and Compton effect as in solid metal there is much higher density of electrons than in a gas. The rate at which these interactions occur depends on the energy, moreover, these effects overlap, that's why the Geiger counter sensitivity varies so much. And I would say it's much lower than 40%, rather around 1%. I have two Soviet MSTR-4 mica window Geiger tubes for X-ray detection. They are quite long, so I thought that maybe they are intended to detect the X-rays through interaction with the gas, but in one book I found that, particularly for this tube, X-rays are detected through the interaction with the metallic layer forming the negative electrode.
On the other hand, this brings one potential advantage, especially the pancake tubes are less sensitive to gamma, therefore having a radioactive source emitting mainly corpuscular radiation (alpha and beta), we can possibly ignore the response to gamma and get to the activity easier.
Thanks for your comment. The interactions which produce detection are indeed more complex than we have portrayed in the video. Direct photoionization of the gas predominates below around 60keV while secondary electrons from the tube due to Compton scattering predominate at higher energies. These concepts are beyond the scope of the video and not terribly relevant for hobbyists. So that part of the presentation was simplified. I have seen 'intrinsic efficiency' estimates of 1% that align with your statement (e.g., Nuclear Radiation Detection, by William Price). The 40% 2pi efficiency cited in the video was based on Paul R. Steinmeyer's article, G-M Pancake Detectors: Everything You’ve Wanted to Know (But Were Afraid to Ask).
@@kinetoscopemicroproduction6418 Thank you for response. I will try to find the books you have mentioned.
Does anyone find a source for the first clip?
Any suggestions on a inexpensive accurate unit that detects gamma at 1R per hour and is simple to use ?
The Better Geiger is about as good as you are going to get at that price. It has a range of 2R/hr. Accuracy decreases as you approach the limit. Otherwise, you are looking at a device several times the price.
@@kinetoscopemicroproduction6418 Maybe not ? The Bosean FS5000 seems to get excellent review and its under $50 new and it measures up to 5 rads per hour. Check it out !
Well, it's been spending a lot of time with the dosimeter next door , coming home late , and being generally secretive . Should I be worried ?
😄
great video!
WOAH BUDDY DON'T HATE ON THE cdv700 Those work better than most of the plastic shit online and those Anton tubes are better than most of the modern ones I had one save me from contamination on my desk it was the only one picking it up because it had a more exposed tube and was much more sensitive unlike the new ones unless it's an end window and honestly modern tubes non micas cannot compete with the Victoreen thin walls
Fnirsi GC01 reliable for fallout survival?
It's better than nothing. But since the Fnirsi is a Geiger counter, it cannot provide a reliable measurement of dose rate for many gamma energies.
Good one !
7:05 Isn't this rather bremsstrahlung being emitted? These are basically X-rays.
The detection is consistent with the inelastic scattering of electrons. Direct measurements of bremsstrahlung with the same unit results in only a slight increase (~20 CPM) over background. So most of the increase shown in the video is due to electron rebound.
14:45 The Geiger Counter isn't more efficient at detecting low-energy Am-241 gammas. It just reads a higher dose for the same activity than it would for Cs-137 gammas. Because the dose per gamma ray declines faster than the probe efficiency declines.
That is not correct. For uncompensated Geiger tubes, there is a greater response at low energies as *documented* by the response curve shown in the video. Longer wavelengths interact more readily with the gases in the tube. The dose rate calculation is not scaled. It is always the same per interaction. This was also documented in the video. The technical consultant for this video is a Nuclear Engineer, and it has also passed muster with other specialists in the field.
Any meter that does not include a certification of calibration traceable to a NIST standard is not worth the components it assembled with. A certified metrology lab such as Cross Precision Measurements will prove without a doubt as to the accuracy of any instrument providing quantitative measurements. That calibration would need to be maintained on a schedule determined by a reputable laboratory.
Lies is absolutely wrong, when you measure you need to know the properties of your devive. Also scintillation detectors has a energy range that depends on a lot of things
Geigers are dead. Pocket gamma spectroscope beats it in most categories, while also doing stuff Geiger can't.