Vintage radioactive wrist watches - Is Radium really nasty?

[jebem]

(01-19-2015 09:06 PM)Katie Wasserman Wrote:  

(01-19-2015 07:22 PM)jebem Wrote:  For instance, inside home the background radiation is about 8 to 10 CPM and this value seems to be the usual in many places around the world.

This is typical for sea level readings from the tube you're using. If you buy an LND-712 you'll see somewhat higher readings as it's more sensitive, I find about 12 to 14 CPM is typical. I also have a much better GM tube counter that uses a 2 inch pancake style tube (with a mica window) that gives background counts of around 35 CPM. This one is calibrated too so I have something to compare my DYI counters to. I also have a few small radiations sources to test with.

My bad. On the other day I did some readings in a rush, like during 10 to 20 seconds only, and somehow I got lower readings than what is expected.

Today I let my GM counter run for 10 minutes and it come up with a total count of 220, so I got an average value of 22 CPM.

However my watch hands Radium radiation source still is nearby, about 60cm away (2 feet) from my workbench, stored in a plastic bag inside a glass bottle inside a plastic case inside a paper bag in a wooden drawer.
I guess the Gamma particles just pass thru all these materials like my knife cutting butter at breakfast, increasing the background radiation level readings a bit

I will have to repeat the readings once I put my Radium source away from my apartment and see if I get a lower count.