For some background, for the past few months I have been trying to collect all the elements on the periodic table. I bought a Geiger counter for the more radioactive elements (specifically the GQ GMC-600 Plus if that helps.)

Anyway, I have been using it for about 3 months and its been awesome, right up until about 20 minutes ago.

I was extracting some Americium from a smoke detector and placing it on the sensor to test how radioactive it was.

I've extracted Americium before, and I did nothing different from what I have done in the past without incident.

Huge bang, ears ringing, drop everything on the ground and run.

That's how loud it was. I thought I accidentally made a nuclear bomb or something (monkey brain turn on when loud noise. Logically I know that 90 microcuries of Americium is not going to "go nuclear" as they say.)

It was only on the sensor for about 5 seconds, and the last reading I saw was it getting to about 700 microsieverts/second. Again, I have done this in the past several times with another equivalent sample of Americium with no negative consequences.

Yeah, so now the Geiger counter is fritzed up. Can't turn on or off well, sticks to one screen and detects nothing. I have no idea what is wrong with it.

It could have been the capacitor blowing up, it could've been the Geiger-Muller tube itself, but I really don't know what I'm looking for. I'm not really an electronics guy, and my heart is still racing. also its 2AM and I need sleep

I have not been able to find a similar story. I just want to know what the heck happened, or even where to start looking.

Edit: After further investigation, it was absolutely the Geiger Muller tube that blew up.

I still have questions.

enter image description here

  • 1
    \$\begingroup\$ Probably manufacturing defect, return to warranty. If you bought it second-hand, the previous owner probably did some "home fix". I would bet on the capacitor since these detectors usually require high voltage. If it was beyond its operating limit, it's possible the Geiger tube drew too much current. Open it and send some pics. \$\endgroup\$
    – Damien
    Commented May 11, 2021 at 8:27
  • \$\begingroup\$ After further investigation, it was absolutely the tube that blew up. \$\endgroup\$ Commented May 23, 2021 at 17:59

4 Answers 4


After getting in contact with the manufacturer, we have determined that the cause of this was me being careless and ignorant.

  1. Apparently this wasn't an explosion, but an implosion.
  2. This was not caused by radiation or electricity at all. I just accidently punctured the extremely fragile mica window of the pancake detector. I held the puck pressing against the mesh, which scratched it.

Basically, this all came down to me not knowing how my tools worked, and not knowing how to properly handle it.

This could have been avoided with a little research.

Ah well, live and learn.

On a separate note, I have been searching the internet for documentation on proper handling of GM tubes, but have been unable to find anything on this particular phenomena. In fact, I have been unable to find another similar story to mine, or any safety precautions to avoid exactly what I did.

I am NOT making excuses for myself.

Obviously if I had done my research to understand how it worked in the first place, instead of just playing with it like a toy, I would have handled it much more cautiously.

I am just seriously wondering why I am unable to find a similar story to what happened to me anywhere. With such expensive and fragile equipment, you would think someone would have a "do not poke or I will implode" somewhere in the manual, but I have been unable to find any documentation that covers this.

It is extremely curious to have the internet fail me for the first time.

I'm not pointing fingers, or blaming my current situation on anyone other than me (I'm really trying to make that clear.)

My personal theory is that google is unable to find the relevant information I am looking for. Given the context of "Geiger counter" and "implosion/explosion", search results quickly become saturated. But even in the documentation of what I could find for pancake detectors and GM tubes, they don't mention this. They do mention what they are supposed to be used on, and what to not use them on (for inaccurate results,) but no "implosion warning."

I am seriously just genuinely, genuinely curious on the utter absence of documentation on this. Seriously, if anyone has any ideas, I'd love to hear them.

TLDR; Not the manufactures fault, pure user error.

The counter was amazing until I messed it up. Would buy again. GQ was nice enough to replace the pancake detector for free.

  • 2
    \$\begingroup\$ Just seen your picture. I'm very surprised a tube failure was violent at all, I have never heard of this. I'll be a lot more careful now with windowed tubes myself! Do mark your answer as the 'answer' too. \$\endgroup\$
    – Cursorkeys
    Commented May 24, 2021 at 8:43
  • \$\begingroup\$ I have never heard of a GM tube imploding before and I have been working in physics/electronics for 40 years \$\endgroup\$ Commented May 24, 2021 at 9:28

It's difficult to give a diagnosis without any more information/pictures. But my first suspicion would be that the HT power-supply has failed.

it could've been the geiger-muller tube itself

They are only under a very light vacuum. You'd barely hear a hiss if it ruptured.

It could have been the capacitor blowing up

Possibly, these things usually have a tiny flyback followed by a multiplier using MLCC capacitors and SMD diodes. A diode in the multiplier might be more likely than a capacitor. Those little diodes are surprisingly loud when they go. MLCCs tend to be a bit more benign in failure.

Components do sometimes just fail, even when used within their rated parameters. But, the power supply may not be that well designed. I have opened a couple of these hobbyist counters and the designs invariably look like it was given to the intern.

Return it for the warranty. And get some proper encapsulated test-sources, you don't want to inhale Americium or get it lost in the carpet.

Edit: The OP has since confirmed the source of failure with the manufacturer. It was the tube, "barely hear a hiss" is apparently totally incorrect for some tubes!

  • \$\begingroup\$ It went off like a bomb, I don't know what to tell you. Would you have any idea what would have caused that? \$\endgroup\$ Commented May 23, 2021 at 18:10

Those mica windows can be pretty fragile; it is just a mineral and the G-M chamber is at about 76 Torr (1/10'th of an atmosphere). Sometimes they use an additive gas like argon or methane (but no oxygen) for different type of particle detections. (alpha detectors may use P10 gas (90% argon/ 10% methane with a touch of freon). Some companies (like LND) ship some detectors in pressure sealed cans because air flight can sometimes damage a detector (pressure differences). Since you realized that you physically damaged the window by contact you now know the importance of that little screen that is supposed to prevent physical contact. At first, when you mentioned the probe "exploded" at a high count rate I was thinking that you had a gas-proportional detector that was filled with pure methane or propane and an arc ignited the fill-gas. Glad to hear that was not the case.


The high-voltage supply in the Geiger counter is somewhat more stressed when supplying the additional tube current at higher radiation levels, so that may be why it popped at that particular instant, but it was likely going to fail sometime soon anyway.

Unless you got it wet, it may have just been a random failure. I would suspect a switching power supply from the 3.7V lithium battery, either the HV supply or the low voltage supply. Often there is enough fault current when the chip fails that the plastic chip package is literally blown apart. Not too much noise if you're across the room, but if it's right by your ear, a bit more disconcerting.

In any case, that's a relatively expensive consumer-level unit and the supplier should be willing to repair or replace it if it's not too old. If you send it back, you may have to specify surface transport because of the lithium cell.


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