Vintage radioactive wrist watches - Is Radium really nasty?

[Manolo Sobrino]

(01-23-2015 05:24 PM)Thomas Radtke Wrote:  @Manolo, are you a radiobiologist? Thanks for your nice summary on ionizing radiation and quality factors. It's been a long time (late 90th) since I worked at the University Clinics of Essen in this field. Spent the most interesting years there :-).

Nope, physicist here . Now doing theory, but I miss all that.

I recommended Turner's book, because that was our text on Radiophysics and Radiation Protection along with Johns and Cunningham and it's a good easy introduction (more for radiobiologists really). Experimentalists bible really is Leo. I like Tsoulfanidis a lot and also the old book from Price. Knoll is good for the obscure stuff, as the Siegbahn ones. I've seen a couple of newer books that look good, but haven't used them. Of course, nothing beats having access to the outrageously expensive hardware and making proper oh-****-those-data-are-just-garbage mistakes... Yeah, interesting sums it up neatly

[jebem]

(01-22-2015 04:45 AM)Katie Wasserman Wrote:  You might find other low-level sources of radiation around your home too. I found that some of the Nixie tube calculators I have have small amount of radioactive gas (krypton 85?) to help get the ionization started. Some ceramic glazes have uranium in them. I have an old Elgin alarm clock/radio with radium painted hands. Ionization-type smoke alarms have a strong , but tiny, alpha source in them. Old color TV tubes emitted radiation until they put lead in the glass, but even then you can still detect a slight increase in the background count at the edge of tube.

And let's not forget about the Thorium based gas mantles.
I have one, ordered some years ago in eBay.
It is amazing how many millions of these units were produced during all these years.
I believe the production was only stopped very recently in most of the parts of the world.
My sample, new in the box, in double sealed plastic bags, gives me more than 2500 CPM when I put the package on top of the SBM-20 GM tube!

Meanwhile I have made some readings with other electronic parts from my old stock.

For instance:

- This Dumont 2501A3 electrostatic CRT made in USA from an old scope gives no reading above the background level.
- The same story for this Philips DG7-32 made in Holland CRT. Nothing.
- Also tried a bunch of low cost but nice IV-11 7-segments VFD russian tubes. Nothing.

- However this Toshiba 75AMB1/9J4 CRT made in Japan gave me a increased count from 22CPM to 26CPM (10 minutes sampling):

[Katie Wasserman]

(01-23-2015 07:52 PM)jebem Wrote:  And let's not forget about the Thorium based gas mantles.
I have one, ordered some years ago in eBay.

Yeah, there's okay to test beta emissions with. The most interesting emitter I have is a surplus 1B22 spark gap tube.