Radium - Geiger Counter Measurements

L Leica

i found this same topic at rolex forum
https://www.rolexforums.com/showthread.php?t=405145

his reading is as high as mine . here is his video

Tony C.

Yes, 84 microsieverts is exceptionally high. In my experience, the typical "high" registers are in the 20-30 range, and I have tested dozens of radium dial watches.

I suppose that the sheer volume of lume on the Enicar was the main problem.

jshaw083

You can't compare measurements of alpha + gamma to that of just gamma.

L Leica

from my understanding, does it needs to be very close (without barrier) to measure alpha ? could it be that the low end geiger meter arent picking every particles?

jshaw083

He's using a pancake mica detector. He's also detecting alpha and gamma. That would account for his very high readings. I'm sure if he used a typical sodium iodide detector, the reading would be much lower from just gamma radiation.

The total measurement will be higher if you're measuring alpha and gamma, but biologically, the alpha radiation isn't as "dangerous". It usually doesn't penetrate skin.

@Leica does your detector also detect alpha radiation? Maybe that's why your reading is extremely high.

jshaw083

I’m not sure what you mean? If you’re measuring just above the crystal you would be picking up some alpha. But yes, you do need to be very close to measure alpha. A few centimètres of air would attenuate much of the alpha radiation, is my understanding at least.

What I’m saying is that if your detector detects both alpha and gamma, that would explain your unusually high readings compared to most of us using detectors that only detect gamma.

L Leica

so alpha will penetrate the crystal? sorry i am bit confused

jshaw083

I just looked up your Geiger counter. It’s a pancake detector that detects alpha and gamma. Yes a certain fraction of alpha will penetrate the crystal. It will be attenuated but will not be gone altogether.

That’s why you’re getting such a high reading. Just like the guy in the video you posted. You’re measuring both alpha and gamma.

The combined reading from alpha and gamma emissions will always be higher than if you just measured gamma alone. If you want to know the amount of gamma emissions from your watch, you’ll need to borrow/buy a separate detector that only measures gamma (such as a sodium iodide detector).


Hope that helps.

jshaw083

Well you can’t guarantee your measuring no alpha at all at that distance, but probably much less.

If anything the experiment you did with the steel probably attenuated all the alpha. You were probably measuring mostly gamma at that point, although a fraction of the gamma would have been attenuated by steel as well.

The most reliable way is to compare your readings with that of another detector that only reads gamma.

L Leica

"Alpha radiation: Alpha particles consist of two protons and two neutrons, and since they have no electrons, carry a positive charge. Due to their size and charge, alpha particles are barely able to penetrate skin and can be stopped completely by a sheet of paper. "

unless there is a leak , wouldn't it not able to penetrate a watch crystal ?


I saw these two Radex counter on amazon , seems like both are GM tube.

jshaw083

Generally I think when you read that alpha particles are attenuated/blocked by a sheet of paper, they're referring more to the fact that in general, alpha particles don't penetrate very far through things or through the air. That doesn't mean no alpha particles at all make it through a sheet of paper. Same applies to a watch crystal. Most of the alpha is blocked, but you probably still do detect a significant amount since it's not all blocked by the crystal.

I don't think anyone out there has ever done a dedicated study looking at what percentage of alpha emissions emitted by radium indices is actually blocked by the crystal and what percentage makes it through.