Geiger counter options

[mitaux8030]

Trash, this'll be right up your alley.
What options has a guy got for obtaining a Geiger Muller counter, for around $100-200? I noticed the Oatley Electronics kit: - but it's been mentioned (here!) that it's not really sensitive, and is really only a gamma particle detector. I suppose there's nothing to say that kit can't be fitted with a more sensitive tube? Looking to detect at least gamma & beta - to go looking for rocks that might fluoresce under UV.

[trash]

$80 is a good price these days. There are lots of options. But this one is you're best bet. It's a kit which most people on this forum could put together.

Bluedog, Brewdog and I all have one of these LCD counters.
Blue has made his self contained, I've made mine with inter changeable sensors.


This one looks similar, and there are quite a few other similar kits out there and they will all pretty much work with most GM tubes.

That brings us to the next question; Which tube do I buy?
Yes, the oatley kits and tubes are a bit... sad. But don't write them off, they can be useful.

So the most common and standard tube out there at the moment is a Russian made SBM-20 tube.
These are a good tube and they're relatively sensitive to both Beta and Gamma radiation and they're cheap.


The going rate is about $20 for a tube. A single tube is all you need to start detecting both beta and gamma radiation, but you might want to use multiple tubes for other reasons. I use an array of 8 tubes one a long probe which makes for a very sensitive GM counter.
I also have three tubes stacked in a cross shape which makes them about 10 times less sensitive, but the probe is directional, it will ignore radiation that does not come from directly in front of the probe and pass through all three tubes.

I have a switch with a tube internal to the case and I can switch to a BNC connector and change the external probes.

The oatley tube which is only sensitive to high energy gamma is useful for determining what isotope you're detecting.
If you compare it to the (Beta+Gamma)-Gamma=Beta. So being able to swap tubes or filter a Beta+Gamma tube to block beta particles can be useful.

Then there is the ability to detect alpha particles.
For that you will want a mylar window GM tube like this one (GMT-01)
Even Jaycar sell these tubes for about the same price. Typically they're about $100 retail, but you can find them for as cheap as $30.
They have several part numbers and there are a couple of different variations, but they all perform much the same.

Pancake tubes are another kind of tube that you can use. The SI-8 is another Russian tube that is good for the job.
They cost about $80 and a very sensitive to alpha particles.



There are a couple of other specialised tubes like neutron tubes or He3 tubes etc. They're more trouble than they are worth at this point in time.
GM tubes are easy to use and cheap to buy and you can do a lot with them. Once you get the hang of radiation detection, then start playing with weird stuff like ion counters or scintillators and neutron detectors.

I've built all kinds of interesting and weird arse counters. Some are fun to play with but not very practical and others are very useful (Like MCA) but a pain in the butt or expensive to get going.

[Uncle Fester]

I ordered an Arduino compatible kit from this seller for about AU$43 incl post (don't think anybody can beat that )


He also has tubes so I bundled an sbt-11 (alpha,beta,gamma) with socket for US$35 extra.
I already have an SBM-20 which I will make switchable in the setup.

If the sbt-11 counts and the SBM-20 doesn't then I will know I am looking at straight alpha (test with ionisation smoke detector)
For the SMB-20 I have got a filter plate to absorb beta to help distinguish the other two but you can make one with aluminium 2-3mm thick.

Info about the kit :

[trash]

It would be amusing to see Am241 source (alpha emitter) that didn't emit gamma rays too.

Aluminium Foil stops Alpha particles right? (it is suppose to stop beta)

[Uncle Fester]

It would be amusing to see Am241 source (alpha emitter) that didn't emit gamma rays too.

Aluminium Foil stops Alpha particles right? (it is suppose to stop beta)

Never said anything about aluminium foil, I said 2-3mm thick aluminium plate and only in regard to beta. No clue how it responds to alpha as I don't have the alpha
counter yet.
As for the Am241 in an old smoke detector, my Russian detector with 2 SBM-20 picks up a fair bit bit of beta but with the gamma plate(that is supposed to filter out beta) I get absolutely nothing.

[gordon_s1942]

Theres been a lot of talk recently of the Federal Government wanting to open a Radioactive waste dump 'somewhere' in NSW and one area under investigation is around the old Gold Mining area of Hill End, NSW.
I was thinking that if a waste dump was opened there, maybe you could build a Geiger Counter combined with a Gold Panning dish and have the best of both Worlds.

[Uncle Fester]

Theres been a lot of talk recently of the Federal Government wanting to open a Radioactive waste dump 'somewhere' in NSW and one area under investigation is around the old Gold Mining area of Hill End, NSW.
I was thinking that if a waste dump was opened there, maybe you could build a Geiger Counter combined with a Gold Panning dish and have the best of both Worlds.

Hills End gold field is already a tourist attraction and if they dump radioactive waste it will get even more popular

[trash]

Generally Nomeat they say that a sheet of paper will stop alpha particles and a sheet of aluminium foil will stop beta.
That is however a generalisation. The energies of each type of radiation play a major role. So the high energy alpha particles from polonium 214 are strong enough to penetrate aluminium. And yet the low energy gamma will barely penetrate paper.

As for radioactive waste, if it were near Hill End you wouldn't be able to keep brewdog out of there.

But radioactive wastes are just made scary by the Greens. Which is a damn shame because their myopic politics make ordinary people dumb, confuse environmental politics and obstruct industry, science and progress.

[mitaux8030]

What a comprehensive response Trash, thank you!
Must give a big shout out for the seller of the kit nomeat mentioned above, he's very helpful indeed. His kit & an SBM-20 tube are on the way for AUD $68 delivered to my door. For that, I'll end up with a flexible and reasonably sensitive (for a single GM tube) Geiger counter. Plenty of scope to change tubes in the future. Anyone looking to get hold of a Geiger counter could certainly do worse.
The adventure begins... hopefully finding some pitchblende or torbernite are in my near future.

[trash]

yep. It's a good choice, you'll have a lot of fun with it.
Do consider ordering yourself a couple of extra SBM-20 tubes they're very handy to have.
And later some kind of window or pancake tube.

The cheapest geiger counter I have made cost ~$10 in spare parts and a $2 tube I found at a flea market.
It is literally a BC548 transistor with a small audio transformer, a couple of resistors, capacitors and diodes with a crystal earphone.
It is just a crystal radio version of geiger counter. A GM tube with a crystal earphone is all that is really needed.
The other components do nothing but provide +350V to the tube.

Disposable camera flash circuits are an even cheaper source of +HV since they're basically thrown out.

And the fun doesn't end there. There are some other simple geiger counters you can make.
Ordinary Red LEDs can be make into detectors. As can 1N914 diodes. They're a rather crappy detectors because the active area is so small.

A better detector is a 2N3055 transistor in a TO3 case. I can hear you all laughing now. No way trash, that would never work!
Remove the metal case and bias the transistor to conduct. There will be natural noise from just light photons hitting the silicon junction.
But what really kicks the transistor are alpha particles. If the transistor is shaded in a box of something and the alpha source introduced to it, it works quite well.

Another method is just to bias a wire mesh sitting about 5mm above a metal plate with about -5kV.
When an alpha particle passes through the mesh, the ionised air breaks down and a spark strikes.
So thousands of particles passing through the mesh makes for very interesting kind of detector.

And then there are could chambers using simple saturated fog like metho and a peltier device.

And last of course are scinillation detectors. Use some kind of crystal or even a piece of perspex and seal it up in a light tight box with a PIN photodiode detector or a PMT tube.

[trash]

[trash]

If you're looking for some radioactive rocks, I have a few good radioactive sources from Rum Jungle and Radium Hill that I keep for swap & trading.

There are a couple of good websites that sell them too.

[Uncle Fester]

Those are US sites with no international shipping except this one I found
that charges about the equivalent AU$100 just for shipping

[trash]

It's really not a problem Nomeat. There are plenty of forwarding companies and consolidated freight that handle items out of the USA.
One company I can think of handles large items like cars. For tiny little items like rocks, they can handle really easy.
It costs them nothing to ship them with other big freight, so just receiving your mail is pure profit.
Very easy to negotiate a price like $10 for each incoming package or just one price for shipping your box based on it's volume (and sometimes weight).
I just explain to them what I am moving and why and how they can help keeping my costs to a minimum while making some easy money for themselves.

Of course if you have a relative or friend that makes things simple.

[CrYpto]

Hello trash , just assembled my first radiation counter using the SBM-20 tube and wondering if you knew anyone in australia where i can purchase some radioactive samples. Postage from the usa is ridiculous.

[trash]

Where you at Crypto?

So Radioactive minerals in Australia are getting harder to find. But Davidite is the most common and cheapest.
There are mineral and lapidary shows all around the country all the time. I can tell you where the next one near you will be.

Brewdog and I are the masters of treasure hunting. Actually, she's got it in the bag and finds some choice stuff.

So op shops are a great place to find stuff cheap.
Uranium glass is pretty common and you will find it in most antique shops.
Most of it is slightly radioactive but some good pieces are quite active.

But don't be afraid to look on the shelves and check everything because a lot of the old glazes are also radioactive.
Yellow glazes are a good example, but some orange glaze is where it's hottest.

Old watches etc with glow in the dark radium paint is very radioactive and easy to find at swap meets etc.

And the good old favourite - the smoke detector.
Not much radiation escapes the smoke detector and Am241 is an alpha emitter.
Find an old smoke detector and bust it open. The Americium is clearly marked in it's little foil shield.
Pull the shield apart and you should find what looks like small metal disk with a tiny metal patch spot welded in the center.
Your counter should confirm that it's the source. So while you won't detect the alpha's, the beta and gamma secondary radiation you will detect easily.

And if all else fails, I've got plenty of antique treasure and minerals.
I've got a bit of Davidite, Autinite, Torbernite, Metatorbernite and Carnotite that I don't mind selling or trading.

*

[CrYpto]

Thanks trash , I got my first source , that being the Am241 out of the smoke detector , I also purchased a thorium doped mantle so that should be arriving soon. I am in Wollongong so I guess I will start looking at some second hand shops and outdoor markets. Also purchased an SBT-11A tube in order to detect alpha particles , cant wait till it arrives. If there are any lapidary shows happening around Wollongong please let me know...thanks.

[trash]

There's one at Blaxland next weekend.
It's not likely that you will find any radioactive rocks at this show, but if you're wandering around with a geiger counter I can assure you that at least one of the dealers (peter) will ask you if you know me and if you're looking for something specific, then he might have something of interest. Davidite, Autinite and Torbernite are common, hot and cheap.
Autinite also glows brightly under UV light.


Blaxland Gem & Mineral Club Open Day
Saturday 7th May 2016
Time: 8:30am – 3:30pm
Where: Progress Association Hall, The Valley Rd, Valley Heights,NSW
Just off the Great Western Highway (north side) in the Blue Mountains at Valley Heights. Park in rail commuter car park and head down past the right hand corner.
Activities: Rocks and slabs for sale, gem cutting and polishing demonstrations, sausage sizzle.

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The Canberra Lapidary Club's 2016 Winter Gemcraft and Mineral Show will be held on Saturday 28 - Sunday 29 May from 10am to 5pm at the Mallee Pavilion, EPIC. Entry is $5 adults, $10 family, $2 children/concession.

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Sat 18th - Sun 19th June 2016
Windor Gem and Mineral Fair, Sydney outskirts NSW
The Fair is a bi-annual fair and is held at The Windsor Function Centre on the corner of George Street and Dight Street Windsor. The fair is hosted by The Hawkesbury Valley Lapidary Club and Crystal Habit. We will have a number of traders from around Australia displaying their wares as well as displays and demonstrations by the Hawkesbury Valley Lapidary Club. A great day out for the whole family. Adults $7, kids with parent/s are free! Opening hours are 9:30 till 5:00 on Saturday and 9:30 till 4:00 on Sunday

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9-10 July 2016
Campbelltown & District Lapidary Club Gem, Mineral & Jewellery Show
Greg Percival Community Centre, Ingleburn, NSW

More info ...

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Sat 27th - Sun 28th August 2016
Carlingford Gem & Mineral Fair, Sydney outskirts NSW
This fair is held at The Roselea Community Centre which is located at 645 Pennant Hills Road. We will have lots of traders from around Australia as well as displays and demonstrations from the 2 local lapidary clubs, Parramatta Holroyd Club as well as Northern Districts Lapidary Club, as well as the NSW Mineralogical Society.
A great day out for the whole family. Adults $7, kids with parent/s are free! Opening hours are 9:30 till 5:00 on Saturday and 9:30 till 4:00 on Sunday.

[CrYpto]

Thanks trash.

[trash]

Peter has a good stock of radioactive rocks, from some cheap Autinite and Tyuyamite for about $20
moderate priced Davidite and Torbernite about $50
and some top shelf stuff like Saleeite which will set you back about $500

He may not have them at each event. So if you see him at one, let him know that you'd like to see more and he will bring a whole tray of them.
I'm always trying to get him to get more Uranium and Thorium minerals but they're not something he goes out of his way to stock.