I have 2 gamma detectors of different size. The Bigger one has 300 cm^2 surface area and the smaller on has 170 cm ^2. Ideally the Smaller detector should be showing the 1/3 less ips than the Bigger Detector for Nulleffect, But its not happening here. I have also taken the readings with Bq/cm^2 unit. the values are identical, which makes sense. Can anyone share their insight why this is happening.

Here's another radiation adjacent audio item besides Polonium brushes. I was reading a column in the October, 2026 issue of Stereophile magazine and came across this description of a Grado phono cartridge the author owns.

A radium impregnated gold & silver plate (mounted above the cantilever) to eliminate static. Cool! I suspect these early Grados are rare and pricey, but I'd love to add one to my small cart collection.

This make me wonder if any other cartridges had this feature?

I spent 20 minutes in a radon bath at the Radium Palace in Jáchymov, Czechia, the world's oldest radon spa. The water is drawn from a working uranium mine (Svornost) and the bath is prescribed and covered by Czech health insurance. I took a Radiacode 102 in with me and measured whatever I could.

What I measured

Room background before the bath: around 0.1 µSv/h. That area is granite, so that is roughly normal for there.

My swimming trunks, straight out of the bath, held flat against the detector: 1.0 to 1.5 µSv/h. The spectrum showed the Pb-214 and Bi-214 gamma lines without much ambiguity, which is what I would expect if radon daughters were plating out on the fabric.

The same trunks, same detector, in a normal room about ten hours later: 0.15 µSv/h and still falling. Skin, washed and out of the water for a few hours, was back at background.

The bit I want help with

Rn-222 has a 3.82 day half-life. Ten hours should leave about 92 percent of the activity if that drop were decay. Mine fell by roughly 90 percent. So my reading is that the signal was the short-lived daughters and not the radon: Pb-214 at 26.8 minutes and Bi-214 at 19.9 minutes decay away within hours once the trunks are out of the water, and nothing replaces them because the radon has gassed off.

Is that the correct explanation, or is something more interesting going on?

Two more if anyone has the patience:

1. How do you properly estimate the dose from a bath like this? Inhaled daughters in the room, activity of the water against skin, ingested water, or something else dominant? I have seen quotes pointing several different ways and I would rather understand it than repeat a number.
2. Does anyone have comparable measurements from other radon spas (Bad Gastein, Bad Schlema, the old Montana ones) to compare the Jáchymov water against? The spa claims theirs is the strongest in Europe and I would rather test that than take their word for it.

I did film the whole thing, measurements included, and I am happy to link it in the comments if people want the detail. Mostly I want the physics checked by people who know more than I do.

I recently got my hands on a cdv-700 and replaced the corotron with a zener stack (3x 300V, specifically 2W 2EZ300D5 300V).

Upon turning it to the 100x scale the needle twitches a tiny bit (1/16th), about 1/8th on the 10x scale and 1/4 on the 1x scale. After that it will gradually drop to zero and not respond to the check source at all.
Does anyone have an idea what could be causing this?

Also i wont be able to source many US parts because i imported that thing all the way to germany for my collection.

Thank you so much in advance

Maxes out at 0.4 mSv/hr rate, readings taken at ~5cm

Hi,
I came across BetterGeigers Radiation Risk Cheat Sheet (images.squarespace-cdn.com ) today, and I have some issues with it, as it seems to have major inaccuracies, oversimplifications, or misleading assumptions. I don't see much radiation safety/medical/emergency management knowledge or guidelines reflected in it.

As this sub has probably quite a lot of people who are/have worked on/with radiation (un-)safely ;) and likely have more experience with it than I do, I wanted to ask if you could review BetterGeiger's version and my attempt at improving it. The use case would most likely be advanced (individual) emergency preparedness/response and, more generally, getting a better sense of the risks over time.

Thanks in advance for genuine interest and comments!
My version is below.

I bet it tastes refreshing.

Why radiation sticks everything?

Metal, liquids, clothes, people...

Ive always been interested in radiation, nuclear physics, and nuclear energy (never cared too much about weapon production) and there was even a point I considered going to college for a career in nuclear physics/nuclear energy, sadly had to shelve that due to lack of facilities in my area and not being able to move, but I realized recently that I know a lot less then I wish I did. What are some great sources to learn more as someone who just views radiation and nuclear physics as a hobby to learn more about it?

What would be a good beginner geiger counter or something that can pick up radiation. I'm not familiar with radiation but like to go to the thrift store and would like to see if i can pick something up or have already bought someting that's emitting rays.

I want to purchase CS-137 in very very small concentration (<0.2uCi) for a personal project of mine in India.
What are the Legal barriers, Restrictions and Limits for it.
Anyone with such purchase experience, please help me out.

Found this one for sale, how good is this one compared to a new but cheap Geiger from Aliexpress? And how much is a fair price? Thanks for any info.

Would this produce additional hazards during the clean up? What about industrial fires and older, more radioactive Plutonium based detectors?

Hey yall I recently got this ludlum 316-3 gate frisker for free. It didn't come with a charger nor any documentation. I can't find any documentation or really anyone besides one guy on YouTube who also owns one. If yall have any docs please send some. Thanks

Came with a WM. B. Johnson and associates inc nuclear scaler. Was also wrapped in lead when I got it.

Oz Geology has an interesting video about the Paralana Hot Springs, which are heated by the radioactive decay.

https://youtu.be/aCdDYk_WBL4

Edit: 36 hour spectroscopy sample in the comments.

I was recently able to get a hold of an expired H.Pylori test kit, which uses C-14 laced capsules. C-14 decays solely by really low energy betas, so a normal geiger or scintillator is useless. They will show up as a moderate reading on a pancake probe or AlphaHound though (≈two hundred cpm over background on my SEI Ranger).

However, apparently the betas can generate equally low energy X-rays through bremsstrahlung, which do have enough energy to trigger a scintillator. I put the capsule in an oversized lead pig with my Radiacode and compared with a 24 hour background reading (green) I apparently am getting a slight hump (leftmost orange) at about the right spot. No idea how accurate a Radiacode is at the bottom of the energy scale, but I am calling that anomalous hump a success.

So, while it may be useless for spectroscopy because of the wide hump of bremsstrahlung energies, it is interesting that you can detect energies below the normal threshold with low budget equipment.

Anyone in the Pittsburgh area that can help with calibrating a Ludlum model 25? Thanks!

I started working at a radiochemical analysis company almost a year ago. I have three lab partners who have been with the company for three years, we are all relatively green in our fields. Two of us are bs chemists, one bs biologist, and one bs biochemist. None of us have been trained on radiochemistry or proper handling/storage.

Our scope is broad, and our PPE is non-existent. Requested safety documents are denied. We have had to call the fire department for risk of immediate volatile explosion (in a radiochemical lab).

Our safety is not considered at any point. We are told to do things we are not comfortable with or do not know how to do, and when we request information we are told "I've been doing it for 40 years it's fine".

The level of disregard for our concerns is insane. We can't financially afford to quit, but we also can't afford hospital bills if this goes bad.

I have been asked to register radiopharmaceuticals for fda, but also told "we're just going to say we do it but not actually". This feels completely irresponsible when it comes to any data, but to ask my faslify data for radiopharmaceutical analysis for fda submission has me blown away.

Our isotopes are stored in a wooden cabinet, not segrated, not properly sealed or labeled. I feel like every time I open the acid cabinet I might blow up, and there's not even isotopes by that.

I our sealed sources are just literally laying in random cabinets and fume hoods (3/3 not graded for radiochemistry and barely work at all due to rusting). I just refused to take inventory due to safety concerns, and I've been on the fence of fired since I brought up the segration concerns my first month.

He's a very well known radiochemist and I fear retaliation for my coworkers and myself for asking for outside help. We just want proper training and safety knowledge, it feels like we're asking too much.

We are all looking for jobs, but nothing yet. We know who to call when we can all safely get out, but we can't be homeless so we are desperately trying to find other work as fast as possible. I have even considered fast food or retail just to get me somewhere where I don't have anxiety about serious injury on a daily basis, but I don't know what that would do to my resume and future employability.

Any radiochemistry or safety professionals who can advise anything else we can do to protect ourselves?

We have all received one 8 hour radsafety course. I have had general lab safety and lab safety program development. I also have my GLPRO and AV01(Pharmacokinetics and Pharmacodynamics) professional certifications. This is the extent of our training. We have never been shown how to handle items in our lab, how to dispose of them... I asked about waste when I started because my last job I was a manager of a higher education chemistry lab and handled all hazardous waste. We do not have waste disposal here. Not a jar, not a contact, not a care. He has his drinking buddy who he hired in the 90s dump EVERYTHING down the drain.

THIS PLACE IS SO WRONG ON SO MANY LEVELS. And to have to choose between homelessness or personal safety is a crazy position for four people under 35.

Photos for attention. All of our isotopes and tracers and spikes and how they are stored and labeled.

it’s gotta be either aluminum or steel, some part of the tube casing is magnetic but I don’t wanna risk damaging anything by separating the pieces.

if it differs per manufacturer or model, I’m using a Victoreen Model 6A.

I pulled the trigger on a great deal for a non functional model 3 (serial number 31737) and 44-3 probe. The probe is an utter mess and the NaI crystal has exploded, clearly due to water damage and previous repair attempts. The Mylar film was replaced with a piece of plastic and everything else was held together with electrical tape. Other than that the photomultiplier tube seems to be in good shape.
Now the actual survey meter is in ok shape with some corrosion, but there are a few snapped resistors that are circled in the picture and one capacitor that I can solder back no problem. But the issue is, I can’t find any diagrams for the first generations of the model 3. And I don’t won’t to risk replacing everything with the wrong Ohm resistor. If you have any pdfs or links that can help me repair this piece of history, please send them my way.

Mostly exposed radium watches. a few amercium buttons.

Or underestimate it, if your gammas are on average higher than that (way less likely I assume).

But: what most of y'all are using your GM counters has nothing to do with fission products, but mainly natural isotopes of various decay chains (U-235, U238, Th232), or maybe some decay chains of non-natural isotopes.

Making the energy estimation of GM counters completely useless - or does it?

Is Cs-137 a somewhat good enough average, despite being the completely wrong isotope? I haven't dug that far, I just know that it's a super wrong estimate for whatever I tried to measure at this point.

Whats your opinion/educated guess?

Alright, so this weekend I dragged my son out into the woods near Munich (South Germany) for another little "science adventure" - and leave Minecraft at home for a while. I knew from previous soil samples that this area got a nice little Chernobyl Cs137 souvenir, with dried/sieved soil hitting up to 800 Bq/kg. Fun stuff.

Since it's mushroom season and we knew some shrooms love to hoover up that radioactive cesium, we figured: let's collect some, dry them at home, and shove them into my efficiency-calibrated gamma spectrometer & lead castle (partly 3D printed).

We took two different species home to see if there is a difference....

Results:

The **Rotfußröhrling** (I think it's called *red-footed bolete* or *chestnut bolete* in English? Someone correct me) came in at 1274 Bq/kg. That's below the EU limit of 6000 Bq/kg for consumption on dried shrooms, for fresh ones it is 600Bq/kg.

So it was easily detectable (last image shows the nice spectrum).

The **falsche Pfifferlinge** (false chanterelles) from the exact same spot? Basically nothing. Nada. Nothing above my detection limit (which I dont know btw, this is still an amateur setup), or nothing above background.

It's honestly fascinating how differently mushrooms take up this stuff. Some are little radioactive sponges, others just don't "care". Biology is weird and cool.

Anyway, good day overall. My son got to see some real science shit, we raised a bit of awareness about environmental contamination, and we spent a nice day in the woods together identifying mushrooms. ☢️🍄

Disclaimer: I know my setup and experiments have for sure several shortcomings, this is amateur level only. Biggest shortcoming: efficiency calibration is done with a dried and sieved soil sample, where I knew the Bq/kg. The matrix is for sure not an equivalent for mushroom tissue - so the error bars are again in the 25% range.

///And: please dont start the discussion about Chernobyl vs Weapons-Testing Cs137 again - we had this so many times and I explained this so often - I am tired of this. In case you are interested you can search up other posts of mine or use google or AI to get that explained - this is south Germany/Europe here.///