r/Radiation Aug 12 '25

Buyer's Guide PSA: Don't Ask "What Geiger Counter Should I Buy?" until you've read this post.

184 Upvotes

The most common question we see in this subreddit is some variant of the "what device do I buy?" question. It's asked multiple times a week, sometimes multiple times a day. It's so common that someone tried to create a flowchart to help newcomers. As well thought-out as that flowchart is, it's like telling someone what car they should buy before they even know what a car is, what it can do, and what it can't do.

If you're looking for the tl;dr or other shortcuts, sorry, there aren't any. This post exists because there are too many "Where do I start?", "What should I buy?" and "I just bought this... is this reading dangerous?" posts from impatient newcomers who expect Reddit to teach them on the fly. Doing that with radiation is a lot like buying a parachute and jumping out of an airplane... then whipping out your mobile device and asking Reddit for instructions. Don't be that guy. Be smarter. Before you run out and buy "baby's first Geiger Counter", you should at least understand:

  • The difference between ionizing and non-ionizing radiation, as well as the main types of radiation (alpha, beta, gamma, x-ray, and neutron).
  • The difference between radiation and radioactive contamination.
  • The difference between CPM and dose rate, and when to use each.
  • The inverse-square law and how distance affects the readings you're looking at.
  • What ALARA is and how time, distance, and shielding reduce exposure.

There are more I could add, especially when it comes to health and safety, or detection devices themselves. But, in my experience, these concepts are the ones that confuse newcomers and lead to erroneous or misleading posts. To help you avoid the pitfalls of buying before knowing, or being "that guy", here are some resources to get you started in learning about Radiation, detection devices, biological effects, etc. Listed from more basic, easy, and approachable to more comprehensive or advanced:

If you prefer a website-based approach with links to other sites, videos, lots of pictures, etc... Head over to the Radiation Emergency Medical Management website's Understanding the Basics About Radiation section and start your journey.

Prefer a textbook approach? Grab a cup of coffee and sit down with the freely available University of Wisconsin's Radiation Safety for Radiation Workers Manual. There's a reason it's still used more than 20 years after it was first published. The book starts with a good basic explanation of radiation and radioactivity. The book then covers biological effects, regulations, lab procedures, how detectors work, X-ray machinery, irradiators, and nuclear reactors. It even has chapters on lasers and RF radiation. Some of the information is student and labworker-specific, but enough of the book's content is written in an approachable manner that it should be on every beginner's "must-read" list.

If the UW manual isn't deep enough for you, pick up a free copy of Dan Gollnick's Basic Radiation Protection Technology (6th Edition) from the NRRPT. Essentially a self-study textbook for Radiation Protection Technologists, this book goes into even greater detail on the concepts, math, and minutiae involved in radiation protection.

All of the above too basic for you? Well, buckle up because MIT offers numerous Radiation-related and Nuclear Engineering courses through its OpenCourseWare program. Starting with Introduction to Nuclear Engineering and Ionizing Radiation, each is a full college course with lectures, homework, and exams. There's even a Do-It-Yourself (DIY) Geiger Counters course.

Congratulations! If you've read this far, you're already on the right track. The above isn't meant to be all-encompassing, and no doubt other Redditors will chime in with other excellent books, websites, and videos to help you get started learning about ionizing radiation and its effects. Before you know it, your decision will have narrowed down some. And, more importantly, your new device will be far more than just a "magic box" that shows you numbers you don't understand.

EDIT: It's stunning how many people are claiming to have read this post, then go right back to making their low-effort "which Geiger Counter do I buy" post anyway. You're supposed to EDUCATE YOURSELF so you don't have to make that repetitive, low-effort, ignorant, spoon-feed-me post. If you do the above, you will know if/when you need alpha or beta capability. You will know whether a dosimeter or a survey meter is the right choice. You will know whether a scintillator, PIN Diode, or GM tube or pancake is the right detector for your application. THAT'S THE WHOLE POINT!

If you're saying to yourself, "I don't want to put THAT much effort into this", then asking for recommendations is a waste of everyone's time.

FINALLY, check out our Buyer's Guide posts. These are posts from people like you, that have particularly good comments and engagement, and answers about purchase options for beginners like yourself. Please take the time to look through them before starting your post. Even if they don't fully answer your question, they and the resources above, should help you ask something more than just a vague "what do I buy?"


r/Radiation 2h ago

VIDEO Got a Wekos Doze. I love these portable Geiger counters.

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11 Upvotes

Ultralight keychain size. It's not as sensitive as scintillators but it reacts quickly. The best thing is that I can carry it everywhere. Just disappears in the pocket and is affordable enough as a first Geiger counter.

Technically they say it's a dosimeter. Sorry for the naive question but what's the difference between a Geiger counter and a dosimeter. Afaik it shows accumulated dose but it also shows live readings and it's GM tube based so shouldn't it be a Geiger counter as well?


r/Radiation 16h ago

General Discussion Help with finding Sources

12 Upvotes

I just ordered a Radiacode 102. I have some Vasaline and Uranium Glass. But I am wanting more sources. Ores maybe trenitite, I know I can get some from old smoke dectors. But I am wanting some others. "Safe" Stuff to start out with before getting anything hot or that I would need paper work for. Any ideas?


r/Radiation 17h ago

Questions Does localized humidity affect (reduce) levels of ionizing radiation?

8 Upvotes

I am not nearly as knowledgeable on the subject as most are here, so I do apologize for that upfront.

I have a radiacode 10, which measures inside of my bathroom and bedroom around 53.4nSv/h up to 58nSv/h.

I just happened to read the first number I listed before I got into the shower. I take decently hot showers, more than enough to steam the room up by accident.

I got out and went to pat it dry just in case, but before I started to I noticed it dropped down to about 36.4nSv/h. It has NEVER read that low in my house before.

I begun to wonder: could increased water molecules in the air act as a sort of temporary "barrier/medium" for ionizing radiation to to influence before it reaches my scintillator? As the steam cleared it has since started to read normal levels again (currently between 50.3-51.2nSv/h.) I know temperature can affect the Radiacode's readings as well, but I am not yet sure.

I have not found much in relation to the subject that fits most of the criteria of this experience (closed-room, single detection source, random background radiation and poor parameters on my end, but still distinct enough from say outside of a single room or even the house; most of what I read measured a large land's-worth of humidity instead and average radiation from multiple sources)


r/Radiation 2d ago

Questions Who here has an sbt-10a tube? Maximum cpm you can get?

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16 Upvotes

Hey, quick question! I've had a sbt-10a for a few years, and while it's quite good, I've noticed it gets overwhelmed very easily. I have a radiacode 103 but I run that SBT on the cheap cajoe boards from AliExpress, it won't go over ~190k cpm. I'm absolutely sure the source would give over 190k, it reaches that from a certain distance then gets saturated and starts to drop. Just wanted to know, how high should it go? I've tried using individual 10 megaohm resistors with each anode, but that didn't help much.

Thanks!

(Also, here's the 3d printed probe I'm building for it)


r/Radiation 2d ago

Questions Does anyone know if it would be possibile to ship Exploranium GR-135 with the check source to Poland?

3 Upvotes

I wany to buy Exploranium GR-135 but i don't know if it would be possible to ship to Poland because of the check source and the Seller won't ship directly. Does anyone know what to do?


r/Radiation 4d ago

Radioactive Materials Some spice. That’s a thorium mantle under the leather and my diy soviet tube Geiger counter

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44 Upvotes

r/Radiation 5d ago

VIDEO Radioactive puck in Pripyat

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459 Upvotes

Will be posting more vids from that trip. Anyone know what that puck is?


r/Radiation 7d ago

VIDEO A hot point on Eureka mine

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96 Upvotes

It is an accumulation of secondary uranium minerals deposited by rainwater.

Althrough It isn't visible in the video, the compresor pipe (used to supply air or pump out water) is right next to It.

Edit: My brother recorded the video, not me. When he showed me how he’d done it, I scolded him for the stupid thing he’d done; we went down to a fountain to wash his hands, then used a whole pack of wet wipes to make sure nothing was left, and finally washed them again in the shower.

As for the device, I took off the case and washed it thoroughly in the same way.


r/Radiation 7d ago

Questions Where to get lol (lots of lead) for cheap?

7 Upvotes

Would ideally like to find some sheets


r/Radiation 7d ago

MOD APPROVED Dear Turkish Enthusiasts, r/Radyasyon is now open!

10 Upvotes

You! Turkish Redditor,
We all know and love r/Radiation already, but wouldn’t it be nice to have a place where we can discuss, converse, learn and research all in our native tongue?
Wouldn’t we want to create and grow a Turkish radiation community on Reddit? If so, r/radyasyon is waiting for you! All kinds of enthusiasts are welcome, whether you join to share your geiger collection or uranium glass collection, or to share your moments, or to question the very essence of Radiation, or to simply sip a cup of tea and chat with us and ask us about radiation… you’re welcome to the Turkish Enthusiasts’ heart of Ionizing Radiation, r/radyasyon!

Here is the link for the Turkish welcome message

https://www.reddit.com/r/radyasyon/s/vztr40pcC1

See you in r/radyasyon!


r/Radiation 8d ago

Equipment Got these well picking through my grandpas garage, looking for some knowledge on them

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35 Upvotes

I’ve got a very rudimentary knowledge of the subject of radiation so any knowledge would be helpful. I know they are detectors of some sort but aside from a quick google search of the brands I don’t know much about them. Thought they were neat and wanted to share and learn more, thanks.


r/Radiation 9d ago

Questions Whats the symbol beside Gamma? ID-1 Dosimeter Pen

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58 Upvotes

I mean it looks like an n for neutrons but that sounds so petty. Its certainly not something Id imagine measuring with a Piezoelectric dosimeter.

I also know that the letter n is н in cyrillic alphabet…

I then assumed п, the letter p in cyrillic alphabet, protons..? …What?

My assumptions are its none of these, but I thought some of you guys may know

Whats that near ɣ?

Now that I think of it, there’s a low chance ɣ isn’t even G for gamma here, and that would be embarrassing for me of it wasnt.

Edit: off topic but you can’t imagine how hard it was for me to get a clear image of this. 😅

ANSWERED: It actually is n for Neutrons!


r/Radiation 9d ago

Equipment Gc 01 2023 model

4 Upvotes

Is this a genuine one and what tube is that please?? Radpro gives about .2 usv/h background as hh614 (which matches my gc03) and as m4011 .08 usv/h , confused.

Photo in comment


r/Radiation 9d ago

Careers Why do candidates shy away from radiation protection roles?

14 Upvotes

I have been recruiting for a lab supervisor. I get quite a bit of interest from experienced lab personnel with management/supervisory experience but they tend to fall back when they hear that the role is in the radiation protection department.

Another downside is that many of them are not interested in advancing their careers, and the company is looking for an ambitious person who wants to eventually become a Health Physicist.


r/Radiation 10d ago

General Discussion Something a little different: Just found out my daughter will be trying out for “Radium Girls” - Her HS Fall Play!

30 Upvotes

She is a history buff and also very interested in science and technology so it’s a nice intersection. I have no technical background in radiation specifically but am also a history/science and technology oriented person and therefore curious about all things associated with the discovery/development of atomic energy.


r/Radiation 10d ago

What To Buy? Inquiry about the second-hand MRADs on ebay

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21 Upvotes

According to all the data Ive found, these meters (MRAD-103) should be quite reliable, which is weird considering how they use a geiger tube, nonetheless, I am worried if these second hand units actually do still function well and read reasonable doses.
Does anyone here own one of these? What type of battery do they require? Do they actually function well, or has time made them obsolete to use? Whats their response to low and high energy fields? My assumption would be it would suck at low energies because of the claimed metal shielding of the tube, but im still curious anyway. Can they actually go up to 500Rem/hour? 5 sieverts sure is a solid limit for something that fits into my hand id say. But is it actually reliable as its claimed?
And most importantly does the metal shielding block all Beta rays?

You may also give other information you’d think Id need to know if you own one, thanks!


r/Radiation 11d ago

VIDEO Introducing my "Doomsday Orb" Tabletop Radiation Detector! Details in comments.

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43 Upvotes

r/Radiation 12d ago

Spectroscopy Mystery radioactive spike on wooden fence

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225 Upvotes

I could not tell if it was coming from the fence or behind the fence. It peaked at over 600 CPM. This a similar post i made on a different sub.


r/Radiation 12d ago

Equipment DP-2 meter testing after repair

12 Upvotes

Recently repaired it by replacing the internal ЕМ-4 vacuum tube which had exploded somehow, glad that was the only problem with it. These meters are easy to excite if you place an americium button practically inside the ionization chamber. I don’t recommend it though you can be electrocuted.


r/Radiation 13d ago

Spectroscopy New lead castle!

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28 Upvotes

6x 2”x4”x8” lead bricks, painted to reduce lead contamination. Pictured is the lead castle itself, the count and dose rates on the Radiacode 103 (in the silicone case) outside then inside the castle, then the shielding potential with a 1uCi (+/- 20%) Co-60 source which was produced on 07/18/2025 outside then inside the castle (measured with the Radiacode 103 in the silicone case, then the Ludlum 2241 using a 44-9 pancake probe). Cheers! This is an estimated 96.43% (using 4.47cps to 0.16cps, the 0.16 was measured later and found to be more accurate than the 0.06) reduction in background!


r/Radiation 13d ago

PHOTO Nasty but cool document pertaining to the Nevada nuclear tests.

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29 Upvotes

r/Radiation 14d ago

PHOTO My dad got a radioactive injection

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196 Upvotes

As the title says, my dad got injected with a radioactive solution for a cardiological test. Out of curiosity I brought my Bosean when I picked him up and it freaked out as soon as he opened the door. The highest dosage was measured at his hear, that's also where the picture was taken. For reference, the backgroundradiation in my car is aroung 0.13μSv


r/Radiation 14d ago

What To Buy? Zero or the 100 series?

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9 Upvotes

Im aware these devices serve completely different purposes, however I have some questions regarding especially the Zero.

Is it sensitive to Beta rays only and less sensitive to Gamma? Ive heard this from some people now. I strongly prefer Gamma sensitivity.

Is 16cps for 1uSv/h really bad compared to 30cps for 1uSv/h?

Does Zero actually provide meaningful readings below 1msv/h? Ive seen a video of it where it behaves really poorly and another one where its dose reading is significantly off.

I, if possible that is, want to obtain a counter that can measure high levels of gamma radiation, and still want it to be somewhat accurate in low range conditions. At least behave better and give accurate measurements than something like better geiger S-1 or GMC320+…

(I used to own a RC103, but got fed up after its spectrometry behaved badly and no amount of calibrations fixed it, so i had to refund it.

But that was then, I no longer adamantly seek to do basic nor advanced spectroscopy. Might prefer having it, but certainly not the game maker.)

All those aside, is Zero really reliable compared to the 100 series?

Better yet, are there contenders to radiacode for high range performance and accuracy?


r/Radiation 15d ago

Health and Safety Flight crews and cancer.

25 Upvotes