Radioactive Nixies - Study

[SWISSNIXIE - Jonathan F.]

Hi

This might be a little off topic or irrelevant, but maybe someone is interested in it too.

One of my hobbies aside nixies is technology related with radiation and nuclear (geiger counters, etc).
Today i was sorting my nixies into boxes and held a B-5092-A from Burroughs, as i spotted a print that looked like a part of a radiation warning sign, i inspected all of my B-5092-A - and bingo, one had the complete sing. So this tubes are or have been radioactive.

Before anyone gets nervous about having possible radioactive nixies i will write a detailed report about this.


For these who not know, everything is radioactive, even the air we breathe all day - this is because of the naturally occuring radiation comming from minerals and of cosmic rays entering or earth. A Geiger Counter measures radiation events in time, usually "counts per minute" or "counts per second". The background-rate depends on your location (e.g. in the montains you have a higher rate than in cities). The CPM (counts perminute) depend on the type of detector - but the calculated dose should always be the same (some detecors for example give you 100cpm others only 1cpm but with their conversion factors both end up giving the same dose).

The normal background dose on earth is usually 0.1 to 0.5 microSievert/hour (uS/h)

My background at home is 0.15 uS/h  which is 40 CPM with my type of detector.

The B-5092-A reads only about 100 CPM (0.4 uS/h)

Is it dangerous for your health? - Far from it! You could carry this tube your whole life around your neck and it would not endanger your health.

For example, an intercontinental airline flight will give your up to 3.00 uS/h and not even this is dangerous - it only would affect you if you would fly constantely for years.

So this tubes are perfectly save to carry and handle! There maybe potential way more dangerous items in your house - like watches with glowing digits.


*** OFF TOPIC ***

But why is the tube radioactive, and whats in it?

To answer this you need to look in deeper in radiation.
There are 5 types of radioactive "rays"

Alpha :                Can only travel a few centimeter, and are not possible to penetrate paper. So if you put a paper over a alpha source, you will not - or very low - notice it
Beta  :                 Can penetrate thin objects, can not penetrate metals like aluminium
Gamma:              Can penetrate solid objects, penetrate medium thick metals. Usually stopped by lead shielding
Neutron:              Very high energy radiation, can nearly penetrate everything, concrete, lead etc
X-Rays:               Special form of radiation, tend to "bounce off" shields instead of getting in ther.


I tested the tube with different Geiger-Tubes. The tube does not contain a isotope (radioactive element) that is 100% alpha radiation, since alpha can not penetrate the glass.
Also, the isotope cant be 100% gamma, since a gamma geiger tube does not pick up a significant change.
So the isotope we are looking for is potentialli a beta-isotope and is a gas. The isotpe must have a relative long half-life too.

Whats half-life?
An unit to measure how long it takes for a radioactive element to be just half of its activity. Eg. if your have 100 today, and the half-live is 10 years, there will be only 50 left in 10 years!

I did a little reseach and the gas we are looking for is Krypton Kr-85
It was used in different types of tubes, usually to help ignite something (like a nixie digit).

Facts on Kr-85:

It has a half life of nearly 11 Years, this means if the tube is 30 years old, today only 12.5% of its radioactive gas is still active.
The only way Kr-85 could affect your health is when you drop the tube and inhale the gas.

But by the fact, that there is such a small amount and only a few activity of it left, the gas would merge directly with the room air and would not be dangerous.

Last but not least ;) - the tube is NOT SAVE FOR EATING :-) for various other reasons!

[Paolo Cravero]

Very interesting Jonathan.

 Any chance you could share a picture of the little warning sign and its position? 

I have very few of those Nixies and all tested negative, but my counter is quite insensitive. 

Thank you!

Paolo

[gregebert]

1 tube may produce 0.4uSv/Hr, but a clock with many more tubes will produce more radiation. I have a total of 47 nixie tubes operating in my home, plus another 6 at work. However, most of my tubes are at least 50 years old, so I'm not too concerned. 

[Tidak Ada]

Also 42-Ar is a source of ß-radiaiton, that is used in tubes, even starters for fluorescent lamps!

 

Anyhow, radioactive isotopes are more frequently used in electron tubes. Particular tubes for transmitting and radar purpose. Thorium is allied to Tungsten in filaments for HF power tubes to enhance emission and CO-60 is used to enhance ignition of TR-cells (Transmit-receive cells), who are used to short-circuit the receiving part of an radar system during a transmitting a pulse. Thus to protect the delicate electronics in the receiver front-end.

 

eric

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[Charles MacDonald]

But how many Bananas and Brazil nuts do you keep around. those are the
real home based radiation sources...


--
Charles MacDonald Stittsville Ontario
cm...@zeusprune.ca Just Beyond the Fringe
No Microsoft Products were used in sending this e-mail.

[NeonJohn]

On 03/12/2017 06:16 PM, Charles MacDonald wrote:

> But how many Bananas and Brazil nuts do you keep around. those are the
> real home based radiation sources...
>
>

http://www.neon-john.com/Nuke/Salt_substitute.jpg
http://www.neon-john.com/Nuke/K40_on_geiger_counter.jpg
http://www.neon-john.com/Nuke/Nuke_Index.htm

The K-40 in salt substitute is by far the hottest thing in an ordinary
house.

John

--
John DeArmond
Tellico Plains, Occupied TN
http://www.tnduction.com <-- THE source for induction heaters
http://www.neon-john.com <-- email from here
http://www.johndearmond.com <-- Best damned Blog on the net
PGP key: wwwkeys.pgp.net: BCB68D77

[NeonJohn]

On 03/12/2017 03:41 PM, SWISSNIXIE - Jonathan F. wrote:

> It has a half life of nearly 11 Years, this means if the tube is 30 years
> old, today only 12.5% of its radioactive gas is still active.

> The only way Kr-85 *could* affect your health is when you drop the tube and
> inhale the gas.

Nixie tubes contained about 1uCi of Kr-85 when new. That quantity of
gas absolutely positively without question or doubt poses NO, NONE,
NADDA risk to humans.

I'm a retired nuclear engineer whose specialty is dealing with very
large amounts of radiation and radioactive materials. Like 10,000 Ci of
Kr-85 at a time. So I have some experience in this area.

BTW, for anyone making glow discharge tubes (Dalbor!), custom gas
mixtures including Kr-85 as a component can be purchased here

http://www.specgasinc.com/

They're great to deal with and don't mind dealing with small customers.

[Paul Andrews]

I have often wondered about taking a geiger counter to my tubes. Call me paranoid, but I wonder where some of the NOS tubes come from precisely.

[SWISSNIXIE - Jonathan F.]

@ Paolo Cravero

Attached is an image of my tube. For detection of the Kr85 in this tube you need a beta-sensitve counter that is placed close to the tube.  Just 1-2 cm away you cant detect it anymore


@gregebert

If you have more tubes, only the area that is radioactive will be greater, the actual radiation is still 0.4uS/h  but the area is now 6 tubes. You would only get more radiation if you would take 6 tubes in your hand. When in a clock most of the tube is shielded by the case. And for beta radiation - after penetrating the tube glass its only really weak, a few centimeters away you cant detect it anymore.



@NeonJohn

Nice! Thats a very interesting field of work :) and wow. 10k Ci Kr-85 thats really much - beside that, Kr-85 seems to be "quite save" for authorities, since here in Switzerland i could legally own up to 200mCi - which is a giant amount compared to other isotopes (like Sr-90 1.2uCi).

Nice to hear that this nixie contained 1uCi of Kr-85, this leaves me with around 1nCi left

[SWISSNIXIE - Jonathan F.]

Here is the image

[GastonP]

Well, I have bought a couple of old gas lamp mantle spares, the ones that shine *very* bright, and use them to check my geiger counters too. They use thorium to give out that extra bright. New ones are made with another process, not so bright but with no radioactive substances either. As far as I know some chinese vendors still sell the thorium covered ones.
I would tend to think that this would be hotter (radiation wise, of course) than low sodium salt. At least that's what I measured at home.

Gaston

[NeonJohn]

I didn't include the mantles because most people don't have them. A lot
of people use the salt substitute.

The Coleman replacement mantles sold by Century and made in India are
still quite hot.

http://www.neon-john.com/Nuke/century_mantle.jpg

Last time I checked, WalMart still carried them.

John

On 03/13/2017 10:37 AM, GastonP wrote:
> Well, I have bought a couple of old gas lamp mantle spares, the ones that
> shine *very* bright, and use them to check my geiger counters too. They use
> thorium to give out that extra bright. New ones are made with another
> process, not so bright but with no radioactive substances either. As far as
> I know some chinese vendors still sell the thorium covered ones.
> I would tend to think that this would be hotter (radiation wise, of course)
> than low sodium salt. At least that's what I measured at home.

[SWISSNIXIE - Jonathan F.]

Another really hot source that can be found at home is maybe in a smoke detector!

Some smoke-detecors use Am-241 sources to ionize the air.  But the sources are encapsulated and you only can detect them if you disassemble your smoke alarm (which i would not do!)

[Alic]

Here is another one in white :-)

[Terry Kennedy]

On Sunday, March 12, 2017 at 11:17:31 PM UTC-4, Paul Andrews wrote:

I have often wondered about taking a geiger counter to my tubes. Call me paranoid, but I wonder where some of the NOS tubes come from precisely.

Some years ago I bought an Elektronika 7-06K from an eBay seller in Ukraine. It was full of the most noxious dust I could imagine - like finely pulverized concrete, but very acrid. I asked the seller where he got the clock, and he said "A disused industrial premise approximately 100km NNW of Kiev". I don't know if he was kidding or not, but Chernobyl definitely had some 7-06K's: http://newsinphoto.ru/wp-content/uploads/2011/04/chernocY-960x667.jpg

[newxito]

I begin to get really nervous, I think I'll buy a geiger counter

[Paolo Cravero]

On Tue, Mar 14, 2017 at 9:25 AM, newxito wrote:

I begin to get really nervous, I think I'll buy a geiger counter

Measuring radioactivity is a science itself and to get meaningful data you need to have a good understanding of the phenomena (physics).

For example, measuring emissions close to the object will never represent real-life situations where Nixies (in this case) sit on a shelf in the living room. Also, an object that has been in a radioactive environment doesn't turn active itself (in general). I am sure NeonJohn could tell a lot about this subject.

If you are into building circuits, search for "BPW34 counter" and pick one: this will give you an initial idea of what is active around you. The photodiode must be shielded from light (but not too much otherwise you block beta/weak radiation).

For a very quick way, get the Radioactivity Counter by Mr Klein (both Android and Apple) that uses the photocamera of a smartphone operated in darkness (use kitchen Alu foil kept in place by the back cover: removable, mechanical, no sticky tape needed thus reusable on the field). His documentation also does a good job explaining how to operate properly the App, which creates a background for the BPW34 too. You won't get absolute uS/h values, but you'll begin to "see" what is around you. Note that it took me months before I came across something active. Also note that the photocamera is sensitive to a definite range of energy in ionizing particles (smtg like 200 to 600 kEv), so you won't get weaks and strongs, but it is a starting point IMO.

That said, counters with Geiger-Muller tubes seem to hold their market value, but you need to understand what the meter is telling you, and how you measure.

As Jonathan said, with Nixies the higher danger is through ingestion, but for other obvious reasons!

Paolo

PS: thanks for both 5092A pictures. Looks like mine are normal 5092.

[Luca Bertagnolio]

On 14 March 2017 at 09:25:17, newxito (axt...@gmail.com) wrote:

I begin to get really nervous, I think I'll buy a geiger counter

a geiger counter will do nothing to reduce your nervousness, in fact it might even make it worse, for no real good reason.

What can help you dominate your unwarranted nervousness about radiation is studying the topic, and understanding how much it has been inflated by the media and politicians, which love it as a topic, because it helps them a great deal in selling their “product”, be it newspapers, magazines, clicks on a website, or votes.

If you are curious, then you can find these two resources, freely available online, interesting:

http://nuclear4life.com/

http://www.mn.uio.no/fysikk/tjenester/kunnskap/straling/radiation-and-health-2015.pdf

Welcome to the fascinating world of radiation, known by little and feared by most, for no good reason. More people have been killed by fear of radiation than by radiation itself.

Bye, Luca

[Paul Andrews]

Which is where my thoughts about the provenance of tubes from the Ukraine arises. Where are these warehouses that for some reason still have large quantities of Nixie tubes in them?

This doesn't keep me up at night, but I would like to know. Perhaps someone could make a documentary about the supply chain for old Nixie tubes from the former USSR? I'm not sure there would be a huge market for it though!

[John Rehwinkel]

a geiger counter will do nothing to reduce your nervousness, in fact it might even make it worse, for no real good reason.

Quite true.  I have a Geiger counter, and was working on a difficult project at work and kept getting interrupted.  I brought my counter into work and just left it on my desk, clicking at the usual background radiation.  It made people really nervous and they pretty much left me alone.

One time, I was taking a trip to Mexico to do some shopping, and brought it with me, just in case there might still be some Fiesta ware out there.  TSA searched my luggage every single time while it was there.

As for radioactive equipment, I used to work for a firm that built monitoring gear for nuclear testing.  In one test, the tunnel collapsed, crushing our equipment enclosure.  A couple of years later, we got a call, saying our gear had been excavated, but it was full of probably-radioactive dust and partly crushed, asking if we still wanted it.  We declined, but I assume some gear like that surfaces at equipment auctions occasionally.  Maybe I should bring my counter to hamfests?

I had a pet that was treated with iodine-131 for hyperthyroidism once.  I was told to discard any bedding after a week, because it would "become radioactive".  I-131 is a beta emitter, and beta rays (which are just electrons) can't make things radioactive, it takes neutrons to do that.  The only real dangers are excreted I-131 and, if the betas are energetic enough, and I use materials of high atomic weight as bedding, they could produce X rays.

Welcome to the fascinating world of radiation, known by little and feared by most, for no good reason. More people have been killed by fear of radiation than by radiation itself.

Truth.

- John

[JohnK]

There are persistant reports here that some equipment buried at Maralinga [British A-bomb tests] found its way to the surplus market [ie Waltham Trading in Rundle Street, for those who are local. When I was at school I used to have a part time job there in the mid '60s.].

 

John K

Australia

 

 

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[Dekatron42]

So how should I do to properly test all old instruments and tubes that I buy to check that they are safe, free from harmful radiation, is there any reliable equipment that don't cost an arm and a leg that I can use at home?

I'm not particularly afraid but if there is an easy way to check then it might be a good idea.

/Martin

[H. Carl Ott]

On Tue, Mar 14, 2017 at 8:52 AM, John Rehwinkel <jre...@mac.com> wrote:

 We declined, but I assume some gear like that surfaces at equipment auctions occasionally.  Maybe I should bring my counter to hamfests?

I always bring a pocket geiger counter to the hamfests I attend. 

 So far It's mostly been radium dialed military meters and some odd pieces of fiestaware .  

  But lots of vintage electronics did incorporate radioactive emitters,  so you never know.       

  Some of the meters were actually pretty "hot". 

carl
--------------------------------------------------------
Henry Carl Ott   N2RVQ    hcar...@gmail.com

[NeonJohn]

On 03/14/2017 05:05 AM, Luca Bertagnolio wrote:

> Welcome to the fascinating world of radiation, known by little and
> feared by most, for no good reason. More people have been killed by
> fear of radiation than by radiation itself.

This is literally true. Several people were killed fleeing Three Mile
Island when the accident was wholly contained on-side and no off-site
radiation was measured.

John

[robin bussell]

On 14/03/2017 13:14, Dekatron42 wrote:
> So how should I do to properly test all old instruments and tubes that I
> buy to check that they are safe, free from harmful radiation, is there
> any reliable equipment that don't cost an arm and a leg that I can use
> at home?

If you have a place that can develop it then maybe photographic film?
Or this stuff:
https://uk.impossible-project.com/collections/film-for-polaroid-600-cameras

Though as to the practical details of how to expose and for how long I
have no idea!

[John Rehwinkel]

So how should I do to properly test all old instruments and tubes that I buy to check that they are safe, free from harmful radiation, is there any reliable equipment that don't cost an arm and a leg that I can use at home?

The BWP34 ones mentioned before are probably the most cost effective.  Here's Elektor's version:

https://www.element14.com/community/servlet/JiveServlet/previewBody/41953-102-1-229709/Elektor%20Radiation%20Meter.pdf

Maxim describes a fairly reasonable one here:

http://pdfserv.maximintegrated.com/en/an/AN2236.pdf

If you want to use an actual GM tube, there are kits available, like this open source one ($40 and up):

https://sites.google.com/site/diygeigercounter/buy-the-kit-1

Or this commercial offering ($30):

http://www.goldmine-elec-products.com/prodinfo.asp?number=C8600

For those, you'll have to source the tubes separately, or buy (more expensive) options including tubes.

None of these options will give you lab-grade accuracy, but are completely fine for checking things to see if they're radioactive or not.  For the curious, my go-to Geiger counter is the Black Cat Systems GM-45, with a very sensitive "pancake" style GM tube, but that thing is more expensive at $349.

- John

[alb.001 alb.001]

Electronic Goldmine has lots of Geiger Counter kits and G-M tubes for sale,  Join their e-mail list and you get notification of new products and sales - at least monthly you will find a deal on radiation detecting kits or parts.

I have no relation to the company just a regular user.

Phil

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[franetic]

Just as a curiosity, I have (I had) some boxed ZM1000 nixies branded by RTC (France). See attached photos. The box has a label warning about radioactivity! It probably presents no real danger even if the tube gets broken. (Unless you break a large quantity of those and make sure you inhale the gas.) Note that these are no different that your regular ZM1000's, they were made at the Philips Heerlen factory. (As was every ZM1000 I have had handled.)

[GastonP]

Well, the first thing I did when I built my Geiger counter was to go through all of my ex-USSR sourced stuff. Just in case, you know :).
Nothing hot in there so far.

[David Speck MD]

They are labeled as 3H, for tritium, so they would have a 12 year half life.  Any idea how old they are?

Dave

[SWISSNIXIE - Jonathan F.]

There is no danger about them tubes! Even a few cm away you cant detect the radiation anymore.

8 of the 5092a could not produce a visible gamma spectrometry peak on my professional detector.

For comparison, a 6141 Voltage Regulator Tube does produce a relative big peak.

About tubes from RUS/UKR, the chance you get tubes from chernobyl is very small. It seems the soviet produced large amounts of all kind of stuff, just browse ebay... capacitors,tubes,resistors,geiger tubes.... All can be found in large amounts. Chernobyl is still a military controlled zone, you would not get out there with truckloads of stuff. I guess there are abandodoned factories and storages all over russia where people take materials away. Back to radiation: The soviets even have abandoned nuclear heat generators (RTGs) in lighthouses and military bases, and those things have very dangerous sources in them.

[judg...@gmail.com]

What is your opinion of this one: http://www.ebay.com/itm/Open-source-Geiger-counter-kit-nuclear-radiation-GM-detector-tube-radiation-/161447070168?hash=item2596fec9d8:g:gFMAAOSwcu5UN4Pk

 

From: John Rehwinkel
Sent: Tuesday, March 14, 2017 12:01 PM
To: neoni...@googlegroups.com
Subject: Re: [neonixie-l] Radioactive Nixies - Study

 

So how should I do to properly test all old instruments and tubes that I buy to check that they are safe, free from harmful radiation, is there any reliable equipment that don't cost an arm and a leg that I can use at home?

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[SWISSNIXIE - Jonathan F.]

That kit doesn't look too bad, but 55$ for a Geiger Counter without a display?

For 39$ without a gm tube you could get this one

https://sites.google.com/site/diygeigercounter/buy-the-kit-1

Many tubes are supported, gm-tubes (SbM-20 is a good choice) on ebay.

And...for "just experimenting" you can build your own counter on a breadboard :) only a inductor and a few other things are neccesarry

[gregebert]

Anyone know how the radiation "hazard" of nixies compares to Xrays produced by color televisions/computer monitors that used CRTs ?

[Paul Andrews]

My wife sends us this link: http://thedollop.net/wp/episode-20-dollop/ about David Hahn. I think she means it as a cautionary tale!

On Mar 14, 2017, at 2:01 PM, gregebert <greg...@hotmail.com> wrote:

Anyone know how the radiation "hazard" of nixies compares to Xrays produced by color televisions/computer monitors that used CRTs ?

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[franetic]

Those ZM1000's were made in a year ending in 6 and/or 7 according to the date code. I'm guessing 1976/77. 

[GastonP]

IIRC, correctly calibrated CRT television sets and computer monitors did not emit X-ray at all. Nor any other kind of harmful radiation, for what is worth.
The warnings were related to the operation of the HV rectifier (in times of the vacuum ones, 1B3 and the like) way off its HV maximum limits.

[NeonJohn]

On 03/14/2017 02:01 PM, gregebert wrote:
> Anyone know how the radiation "hazard" of nixies compares to Xrays produced
> by color televisions/computer monitors that used CRTs ?
>

None vs none. As soon as the low level X-rays from TV sets were
discovered and became and issue (two different events), several things
happened

1) All new CRTs had their faceplates made out of leaded glass.
2) the damper tube was made from leaded glass*
3) hard high voltage limiting was instituted.

* A properly made damper tube would not generate X-rays regardless of
the voltage applied. The plate cylinder had to be a little bit out of
concentricity with the filament to produce X-rays.

There was an Amateur Scientist article about how to use a damper tube
and a home-made Odin coil to make an X-ray source. Several fuzzy X-rays
were published.

I made the Odin coil but I could not get any X-rays. My tube was in
good alignment. It took prowling through the inventory of the two TV
repair shops that tolerated this nerdy kid before I found one that worked.

The results were still lousy because the X-rays emanated from all over
the anode's surface. The optical equivalent is trying to take a
shadowgraph photo of an object using and extremely point source LED vs
using light from a recessed fluorescent fixture. Real X-ray tubes use
several tricks to make as close to a point source as possible.

Anyway, back to CRTs. I have a Victoreen survey meter designed
specifically for the CRT industry. It uses an ion chamber with a
super-thin mylar window and is calibrated microR/Hr. I have never
detected anything above background from any of the TVs or CRT monitors
I've owned.

[Tidak Ada]

The radiation hazard is comparable or less that the hazard of a concrete or natural stone wall in your house. however the wall is more less healthy, because Radon is an alpha radiating gas that you inhale in your lungs....

Anyhow, an hour in an airplane at 10,000 ft gives a considerable higher dose.

eric

-----Oorspronkelijk bericht-----
Van: neoni...@googlegroups.com [mailto:neoni...@googlegroups.com] Namens NeonJohn
Verzonden: dinsdag 14 maart 2017 23:38
Aan: neoni...@googlegroups.com
Onderwerp: Re: [neonixie-l] Radioactive Nixies - Study

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[John Rehwinkel]

Electronic Goldmine has lots of Geiger Counter kits and G-M tubes for sale,  Join their e-mail list and you get notification of new products and sales - at least monthly you will find a deal on radiation detecting kits or parts.

Amusingly, just today, they put a pocket size Geiger counter on sale for $40 (down from $130), complete with GM tube.

http://www.goldmine-elec-products.com/prodinfo.asp?number=C7061

- John

[Mark Moulding]

This cute little one just showed up in my in-box - $40:  http://www.goldmine-elec-products.com/prodinfo.asp?number=C7061

~~
Mark Moulding

[NeonJohn]

Be aware that a peanut tube that size will be very insensitive to
environmental radiation. I used a tube that size in my area radiation
monitors designed to be mounted in high radiation areas.

John

> <http://www.goldmine-elec-products.com/prodinfo.asp?number=C7061>
>
> - John

[andybiker]

Regarding radioactive "stuff",
I've had an old clock - about 50mm in diameter that was on an old motorbike I bought about 30 years ago.
Research identifies this as from a WW2 German bomber.
It doesn't glow any more but I took it into work to test it with the geiger counter (that is used for checking X-ray emission from equipment)
They had only ever heard one or two counts per second.
My clock took it up to 100.

Last week I took in my late father's WW2 compass (Magnetic marching MK1)
The paint on the dial and mirror has gone red. (the radium has burnt the phosphor years ago)
The geiger counter went straight up to the top of the scale. 2000 CPS
The room suddenly went VERY quiet.
They started talking then of wrapping this in lead and disposing of it.
I put my compass back in my pocket (I don't want any more kids) and I left, people avoiding me as I did so.
It's now back in my garage.
I don't think nixies are as radioactive as this but we should be a little wary of anything "pre 60s"

Andrew

[NeonJohn]

On 03/15/2017 09:42 AM, Mark Moulding wrote:

> On Tuesday, March 14, 2017 at 10:02:40 AM UTC-7, Paul Andrews wrote:
>>
>> What is your opinion of this one:
>> http://www.ebay.com/itm/Open-source-Geiger-counter-kit-nuclear-radiation-GM-detector-tube-radiation-/161447070168?hash=item2596fec9d8:g:gFMAAOSwcu5UN4Pk

Glass GM tube equals low sensitivity. The thick walls, necessary to
withstand the partial vacuum, will stop most betas, what you're likely
to encounter in the environment. Gamma ray sensitivity will be low but
will be enough to detect the activity from a lantern mantle.

To measure exposure, what you're really interested in, one needs a large
volume energy compensated geiger tube or an ion chamber. An ion chamber
is trivially easy to make - for years Victoreen sold an exposure meter,
the chamber of which was a styrofoam cup coated on the inside with
aquadag to make it conductive.

A smoke detector is an ion chamber. A source is contained within the
chamber. combustion products absorb ionizations, reducing the ion
current and triggering the alarm.

If you're interested in hearing clicks, the tube used in the old CDV-700
civil defense geiger counters will work. Very thin wall metal tubes.
Best is a pancake probe. About $140 from Ludlum and others.

Look guys, this fear of environmental radiation is getting far out of
control. There is ZERO risk from anything radioactive in the
environment unless you happen to eat the hand off a radium watch dial or
an Am-241 source out of a smoke detector. Even then the risk would be
so low as impossible to quantify.

The old and discredited linear, no threshold theory that says that any
amount of radiation is harmful is perpetuated because it has been
monetized. Lots of people are making lots of money "remediating" low
level radioactivity.

The evidence is overwhelming that low level radiation is actually
beneficial. No different than chemical toxins such as arsenic or zinc
or chlorine. Vital trace elements but toxic in higher concentrations.
This theory is called "radiation hormesis".

Here is an article I wrote during the Fukushima accident that explains
the difference.

http://www.johndearmond.com/2011/04/23/fukushima-the-high-cost-of-the-lnt-theory/

A Geiger counter is a fun thing to have around if it is sensitive enough
to detect anything. I carry a pocket unit with the pancake probe's
window facing outward any time I go yard saleing, attend auctions or go
to antique stores. I collect radioactive materials and I've hit some
bonanzas

I especially like to lay the counter on top of some radiophobe's granite
countertop. The unit goes off-scale on the X1 scale. Granite is quite
hot on the environmental activity scale.

As I demonstrate on my nuke page that I already posted, so is wood ash
from the fireplace.

We need to nip this radiophobia in the bud and worry about something
that matters. Like how many Nixie tubes Dalbor can make :-)

[JohnK]

The phosphors wear out. The guys working on old green radios get caught by scraping the labels/switch engraving that have stopped glowing [or the meter dials].  The powder they produce isn't  "safe".

 

John K

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[Paul Andrews]

I don't know about others. For me this is just a new set of techno toys to get to know and play with!

My 18 yr old son recently not-so-patiently explained to me that alpha particles are stopped dead by just about anything. We were 'discussing' whether a nuclear bomb going off on top of a silo containing nuclear war heads would set them off...

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[threeneurons]

A krytron. A gas filled cold cathode trigger tube, containing radioactive material used to detonate a nuke.

A few years back, Westdave had just visited his cardiologist, the day before the TRW swapmeet. He had an exam, that required ingesting some radioactive "juice". At the swapmeet, a vendor was selling a working geiger counter. Dave lit up that puppy.

[SWISSNIXIE - Jonathan F.]

These Krytrons are nice!

I want one so bad, but sadly they seem to be export controlled from united states because they were part of nukes :-(

[JohnK]

"We" used a couple of tiny very sensitive [and fast apparently] scr and
triac devices in an IR movement detector light for home use. Around the time
models were made for the UK market a fax was received from some US agency
via channels. It was a list of countries that it mustn't be exported to.

No attempts were made by anyone to stop re-directors or private export. Yes,
the components were bomb-industry things.
I wonder if it was implied that they would hold the manufacturer
responsible?

John K
Australia

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[Tidak Ada]

Kryptons are also used in big Xerox machines, that spew tens or hundreds of photocopies per minute.

eric

-----Oorspronkelijk bericht-----
Van: neoni...@googlegroups.com [mailto:neoni...@googlegroups.com] Namens JohnK
Verzonden: donderdag 16 maart 2017 10:19
Aan: neoni...@googlegroups.com
Onderwerp: Re: [neonixie-l] Re: Radioactive Nixies - Study

To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/B68AA867745C4A9BA0EA854609ECA444%40compunet4f9da9.

[NeonJohn]

On 03/16/2017 12:42 AM, 'threeneurons' via neonixie-l wrote:

> A few years back, Westdave had just visited his cardiologist, the day
> before the TRW swapmeet. He had an exam, that required ingesting some
> radioactive "juice". At the swapmeet, a vendor was selling a working geiger
> counter. Dave lit up that puppy.

A couple of years ago I had a nuclear stress test run. They injected
the Tc-99 and then told me to go eat a good greasy lunch to help
distribute it. I had brought my Victoreen RO-3 ion chamber exposure
meter with me. I have a selfie of me holding the meter to my chest
where I was emanating 30 mR/hr. Hot stuff, I was.

[John Rehwinkel]

A krytron. A gas filled cold cathode trigger tube, containing radioactive material used to detonate a nuke.

They use Nickel-63 (a beta emitter) to keep the gas ionized so the switching jitter is very low (hundreds of picoseconds, IIRC).  I actually designed these into a circuit once when I was a lab tech while I was in college.  They asked me if I could build this bizarre pulser that ramped the voltage from 2kV to 6kV quadratically, it was going to be used in an electron gun, with the idea that the rear of the electron beam would be going faster than the front, so it would self-compress as it propagated.  I said I could build it, and started cracking books to figure out how.  It turns out they didn't really believe a kid without a degree yet would be able to build such a device, so they gave the same assignment to a grad student.  I used a shaped transmission line as a storage element and the krytron as the switch.  The transmission line assembly was pretty large, but the switch circuitry fit on a teeny board about 5x5cm.  Risetime was about 350ps.  The grad student's effort occupied a much larger board, about 40x40cm, with this long chain of avalanche transistors doing the switching.  His took about ten minutes to get ready between pulses, and it would pop a transistor every few hundred pulses.  While I was testing mine, I was running it at

a few hundred pulses per second, for hours at a time.  I never had a failure.

I probably still have a couple of krytrons.

A few years back, Westdave had just visited his cardiologist, the day before the TRW swapmeet. He had an exam, that required ingesting some radioactive "juice". At the swapmeet, a vendor was selling a working geiger counter. Dave lit up that puppy.

That must have worried/intrigued the onlookers!  You don't get an opportunity like often.

- John

[Dave]

If anyone is interested, I have some extra PCBs for the open source uRADMonitor project.
It's an open source Geiger counter design based on an Arduino with a nice display and ethernet connectivity.
It is all through hole with the exception of one IC on the back of the board. 

Here is the main info link:
uRADMonitor info

Here is a build link where the author shared a case design that I adopted:
uRadMonitor case info thread

My fork for the board is in GitHub and is listed in the above thread.
Mostly just cosmetic silkscreen enhancements.

The boards are only $8.  I also can share my version of the acrylic case that is shown in the thread.
I was able to successfully create an .svg file that you can get cut at ponoko.  It custom fits my version of the board.

Here is a picture of the top and bottom of the board:

[Jack Buechler]

Please could I have one PCB. 

Could you get in touch please.

Jb

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[Dave]

Norskman,
 I have privately replied.
Please do the same or email me so we don't fill up this thread with posts.
thanks

[John Rehwinkel]

This cute little one just showed up in my in-box - $40:  http://www.goldmine-elec-products.com/prodinfo.asp?number=C7061

They have this kit on sale for $10 now:

http://www.goldmine-elec-products.com/prodinfo.asp?number=C8600

- John

[NeonJohn]

On 04/06/2017 11:20 AM, John Rehwinkel wrote:
>> This cute little one just showed up in my in-box - $40: http://www.goldmine-elec-products.com/prodinfo.asp?number=C7061 <http://www.goldmine-elec-products.com/prodinfo.asp?number=C7061>

> They have this kit on sale for $10 now:

No GM tube and only 400 volts which limits its use to a limited
selection of mostly Russian low sensitivity tubes. IMO, not a good deal
even at $10.

[Paul Andrews]

Just got my radioactive nixie tubes. Sadly they seem to make my geiger counter read less than normal!

On Sunday, March 12, 2017 at 3:41:11 PM UTC-4, SWISSNIXIE - Jonathan F. wrote:

Hi

This might be a little off topic or irrelevant, but maybe someone is interested in it too.

One of my hobbies aside nixies is technology related with radiation and nuclear (geiger counters, etc).
Today i was sorting my nixies into boxes and held a B-5092-A from Burroughs, as i spotted a print that looked like a part of a radiation warning sign, i inspected all of my B-5092-A - and bingo, one had the complete sing. So this tubes are or have been radioactive.

Before anyone gets nervous about having possible radioactive nixies i will write a detailed report about this.


For these who not know, everything is radioactive, even the air we breathe all day - this is because of the naturally occuring radiation comming from minerals and of cosmic rays entering or earth. A Geiger Counter measures radiation events in time, usually "counts per minute" or "counts per second". The background-rate depends on your location (e.g. in the montains you have a higher rate than in cities). The CPM (counts perminute) depend on the type of detector - but the calculated dose should always be the same (some detecors for example give you 100cpm others only 1cpm but with their conversion factors both end up giving the same dose).

The normal background dose on earth is usually 0.1 to 0.5 microSievert/hour (uS/h)

My background at home is 0.15 uS/h  which is 40 CPM with my type of detector.

The B-5092-A reads only about 100 CPM (0.4 uS/h)

Is it dangerous for your health? - Far from it! You could carry this tube your whole life around your neck and it would not endanger your health.

For example, an intercontinental airline flight will give your up to 3.00 uS/h and not even this is dangerous - it only would affect you if you would fly constantely for years.

So this tubes are perfectly save to carry and handle! There maybe potential way more dangerous items in your house - like watches with glowing digits.


*** OFF TOPIC ***

But why is the tube radioactive, and whats in it?

To answer this you need to look in deeper in radiation.
There are 5 types of radioactive "rays"

Alpha :                Can only travel a few centimeter, and are not possible to penetrate paper. So if you put a paper over a alpha source, you will not - or very low - notice it
Beta  :                 Can penetrate thin objects, can not penetrate metals like aluminium
Gamma:              Can penetrate solid objects, penetrate medium thick metals. Usually stopped by lead shielding
Neutron:              Very high energy radiation, can nearly penetrate everything, concrete, lead etc
X-Rays:               Special form of radiation, tend to "bounce off" shields instead of getting in ther.


I tested the tube with different Geiger-Tubes. The tube does not contain a isotope (radioactive element) that is 100% alpha radiation, since alpha can not penetrate the glass.
Also, the isotope cant be 100% gamma, since a gamma geiger tube does not pick up a significant change.
So the isotope we are looking for is potentialli a beta-isotope and is a gas. The isotpe must have a relative long half-life too.

Whats half-life?
An unit to measure how long it takes for a radioactive element to be just half of its activity. Eg. if your have 100 today, and the half-live is 10 years, there will be only 50 left in 10 years!

I did a little reseach and the gas we are looking for is Krypton Kr-85
It was used in different types of tubes, usually to help ignite something (like a nixie digit).

Facts on Kr-85:

It has a half life of nearly 11 Years, this means if the tube is 30 years old, today only 12.5% of its radioactive gas is still active.
The only way Kr-85 could affect your health is when you drop the tube and inhale the gas.

But by the fact, that there is such a small amount and only a few activity of it left, the gas would merge directly with the room air and would not be dangerous.

Last but not least ;) - the tube is NOT SAVE FOR EATING :-) for various other reasons!

[SWISSNIXIE - Jonathan F.]

Have you tried to swich them off?

Another note, since Ar-42 is a beta-emita most of the radiation is blocked by the glass, so to measure i would place the tube directly on the geiger tube!

[SWISSNIXIE - Jonathan F.]

I added a picture to give you the idea how far the radiation from a 5092 tube can travel.

The Meter is set to 0.1x, so the 1kCPM equals only 100CPM. As you can see, i read about 100CPM when the tube is placed really close to the detector, and only around 50CPM when moved a 2 centimeteter away. This 50CPM is the natrual background in my lab, so the meter is not picking up the radiation from the tube. The GM-Tube in this detector is a alpha sensitive tube, and so on it is also very sensitive to beta, since its window is not made of metal, but mica material. If you use a metal gm-tube like SBM-20 it might be more difficult to even pick the radiation up.

My B5092 is made in Week 35 of 1966 - the radioactive isotope Kr-85 has a half life of only 10.7years, so after 10.7years only half of the starting value is there, and after 21.4 years only 25% is there!

Lets say the B-5092 contained 1uCi of Kr-85 when fabricated in 1966 - this was around 50years ago - so today only 0.039 uCi of the Kr-85 remains. In a few decades, the radioactive amount will be under detectable levels by professional meters...


See attached a image of a much more active tube, the 6141 Voltage regulator containing KR-85 or RA-226 depending on fabrication date. Mine contains RA-226

[Paul Andrews]

I did try putting the SB-20 on top of a bunch of tubes (a bunch = 3 in this case). It briefly got up to around 120CPM, but mostly hovered around 50-70CPM. I'm not sure what background is at my place. Anything between 15 and 35 CPM maybe. So maybe it registered something, or it could be statistically background. I would have to make a ton more measurements (a ton >> 3) to figure out how this meter behaves and then another ton to see if it was actually measuring anything more with the tubes.

I am mulling over building a case for this meter, but I can't decide how to do it whilst a) not blocking alpha particles and b) not exposing the 450v or so (although we are talking micro amps here). I guess an opening that doesn't expose the terminals would do.

That has given me an idea. I could shield the SBM-20 from all but one direction and then try with the 5092A's again, maybe there will be a more significant difference. What kind of shielding might be necessary?

[SWISSNIXIE - Jonathan F.]

Dont worry about alpha particles, the SBM-20 is made from metal, so alpha particles can't reach the inside of the tube. Alpha particles are usally blocked by a piece of paper or a sufficient space of air. The SBM-20 tube you have is not alpha sensitive, so don't worry about them.

For an accurate measurement, i would record the background counts for like 1hr, and then place the tubes there for one hr, this will get you a better average CPM than short-time samples.

The middle metal part of the tube is GND, so it would be enough to cover the terminals, or cut out a long-hole in the case. Or take a plastic pipe and drill a lot of holes in it.

For shielding i would use lead, have a look at "gamma spectroscopy lead shielding" - it will work for gm tubes as well. Since quality lead will not be available for free, it might be a better idea to get a more sensitive tube. LND Inc will sell pancake tubes LND 7314 (alpha,beta,gamma) and similar tubes that opperate at 500V, they will work at 450 too. The price for a LND7314 is around 115$,and is very similar to the one that is inside the rate meter i have in the picture.

And here you can find a comparison between common geiger tubes: Link!