Sciencemadness Discussion Board

DIY geiger tube?

Fulmen - 4-9-2015 at 09:02

Why isn't anybody making their own tubes? I've searched around and could only find one such build: http://ki3u.byethost3.com/Radio-PhysicsDIR/homemade_GEIGER-T...

I get that they aren't that expensive, but at the same time people seem to make almost anything there is for the fun& challenge of it. So why not geiger tubes? From what I've read they shouldn't be that hard to construct, so what am I missing?

gammainspector - 4-9-2015 at 09:18

In my opinion, a geiger tube is really only useful when surveying for uranium (and not the best tool for the job) or for after a radiation release. Most of the "geiger counters" you see out there are either Civilian Defense units or pancake friskers. Neither of them are designed to monitor airborne radiation levels or in food products.

They aren't super sensitive, they tend to overload, they also don't have a linear response (they over-under respond based on energy of photon) .

I think the better question is, why aren't people building more scintillation counters with BGO or other cheap scintillation crystals that would be much more sensitive and produce data that would be useful scientifically?

Fulmen - 4-9-2015 at 09:52

My use would be mineral detection, I live not too far from an old mine containing uranium and thorium. Would be fun to have a crude detector that could give some relative measurements, and since the physics isn't that complex I figured there would be lots of info on this out there.

gammainspector - 4-9-2015 at 09:58

Ok then I would suggest also you consider the 2" Mica window design instead of the tube design. The performance will be better.

They can be built, there is a seller on ebay "GeoElectronics" who can sell you one or the parts to build one, just send him a message and tell him LH sent you.

[Edited on 4-9-2015 by gammainspector]

Fulmen - 4-9-2015 at 10:19

The structural parts shouldn't be a problem, I have access to both a lathe and a mill. But the lack of DIY-builds makes me wonder if I'm missing something. If it's as simple as I thought (and the link suggests), why aren't people doing this? I can't be the only one who'd get a kick out of a homemade geiger tube? I've seen people making radio tubes for pete's sake...

bobm4360 - 4-9-2015 at 22:11

John Strong's "Procedures in Experimental Physics" at the Internet Archive has all you need to make a Geiger-Muller tube, and many other processes that are useful in more than physics.

Bob

Fulmen - 4-9-2015 at 23:39

Excellent find there, I simply LOVE these old books. Good, concise information for DIY experiments, everything an inquiring mind needs to get himself in trouble ;)

neptunium - 5-9-2015 at 06:53

electronic sensors for the evil genius by Tom Petruzzellis has one such crude counter
http://www.amazon.com/Electronics-Sensors-Evil-Genius-Electr...
no you are neither the only one nor the first...
Besides a good challenge is always fun and even if you dont make it the learning experience is irreplaceable..

Fulmen - 5-9-2015 at 07:06

This seems quite doable, all things considered. I also found this introduction on GM's: https://www.orau.org/ptp/collection/GMs/introgms.htm
The really interesting bit is the "density thickness" for thin walled tubes and mica windows. I assume penetration mainly depends on the mass and not the materials themselves, so wouldn't plastics be a suitable candidate for the window? I have some mylar (BoPET) that weighs in at appr 2,5mg/cm^2, getting it to support a reduced atmosphere (1/10 atm seems common) shouldn't be harder than making multiple small holes.

All I really need for testing is a variable DC supply capable of 1-1,5kV and some radioactive material, an oscilloscope should be able to read the pulses.

Edit: It's not easy finding reliable data for mylar shear strength, but I found some listing it to 15MPa for 5mil and 13,6MPa for 10mil. That's a far cry from the 250MPa listed for grade V-1 mica, but it's not too bad really. My sheet is 1mil, so assuming 15MPa (probably higher) and a safety factor of 3 I get a maximum window size of 4mm for full vacuum.

[Edited on 5-9-15 by Fulmen]

careysub - 6-9-2015 at 07:23

Quote: Originally posted by Fulmen  
It's not easy finding reliable data for mylar shear strength, but I found some listing it to 15MPa for 5mil and 13,6MPa for 10mil. That's a far cry from the 250MPa listed for grade V-1 mica, but it's not too bad really. My sheet is 1mil, so assuming 15MPa (probably higher) and a safety factor of 3 I get a maximum window size of 4mm for full vacuum.


Stainless steel sifting screens of 5 mesh have 4 mm apertures, and 10 and 20 mesh screens (which I found easily on eBay at modest cost) are 2 mm and 0.85 mm. That would seem to be a good support for a mylar window.

mayko - 6-9-2015 at 09:00

I didn't see any projects which specifically built the tube, but the Hack-a-Day geiger counter projects are pretty cool.



Fulmen - 6-9-2015 at 10:53

Mesh screens would probably work, but getting a good seal could be a problem. Probably nothing a bit of epoxy wouldn't fix.

Fulmen - 7-9-2015 at 12:20

The key to a good, fast tube seems to lie in the quenching. Not sure how fast you'd need a tube for casual prospecting, and even slow tubes should count 10-100/s so I don't think one needs to worry too much about it for a proof of concept.
This patent seems to contain a lot of useful information: http://www.google.com/patents/US4501988

Romix - 3-4-2016 at 02:02

Very interesting thread.
Can Geiger tube operate of the battery with led diode?
Is there specific current to go through the tube? Is it different to brands and models?

Need it to test valves for thorium. And broken X-ray guns, there's two powders one grey one white.
I heated one wire covered in it, and inhaled the smoke, it gave me heart kick. And oxide turned yellow.
Last time I opened container in which it is stored. It gave me a heart kick again. Possibly radioactive.

It's under my bed, where I sleep. Is it safe??

553e51047a45.jpg - 141kB
[Edited on 3-4-2016 by Romix]

[Edited on 3-4-2016 by Romix]

Heavy Walter - 3-4-2016 at 05:25

Romix
The picture shows CRT guns.
Powering the filament at open air oxidized the tungsten wire and you got the yellow oxide. They are supposed to be powered under vacuum.
No radiation risk.

Radium212 - 26-6-2017 at 08:52

Quote: Originally posted by Fulmen  
Why isn't anybody making their own tubes? I've searched around and could only find one such build: http://ki3u.byethost3.com/Radio-PhysicsDIR/homemade_GEIGER-T...

I get that they aren't that expensive, but at the same time people seem to make almost anything there is for the fun& challenge of it. So why not geiger tubes? From what I've read they shouldn't be that hard to construct, so what am I missing?

Try H.V Neher's 1938 book, "Building and using Geiger counters". It's got all the instructions you need. You can find it on Etsy or AbeBooks.

Radium212 - 26-6-2017 at 08:53

Quote: Originally posted by Romix  
Very interesting thread.
Can Geiger tube operate of the battery with led diode?
Is there specific current to go through the tube? Is it different to brands and models?

Need it to test valves for thorium. And broken X-ray guns, there's two powders one grey one white.
I heated one wire covered in it, and inhaled the smoke, it gave me heart kick. And oxide turned yellow.
Last time I opened container in which it is stored. It gave me a heart kick again. Possibly radioactive.
Where did you get all those CRT guns ?:D
It's under my bed, where I sleep. Is it safe??


[Edited on 3-4-2016 by Romix]

[Edited on 3-4-2016 by Romix]