[time-nuts] How dangerous if a Rb lamp broken?

[Chuck Harris]

This isotope of radium has a half-life of 1600 years.  It isn't dead, or
even noticeably less radioactive.

Most probably it has burned out the binder that holds the ZnS:Cu material
together and on the digits and hands.

-Chuck Harris

Bill Hawkins wrote:
> Since this thread doesn't appear to have a half-life, perhaps this needs
> some explanation.
>
> The zinc sulfide fluoresces when an atom or more of radium decays. The
> fluorescence will still occur in the presence of ionizing radiation. The
> radium, OTOH, is nearly dead. Probability says that some number of atoms
> will leave their radioactive state and become inert (Lead? I haven't got
> time to look it up so I'll share my ignorance with you. Someone will
> correct me and the thread will never die.) The rate at which a mass of
> radium becomes inert is expressed as its half-life, which is the TIME
> that it takes for half of the remaining radium to become inert. The
> decay is exponential, as are so many natural things. You'll need a
> sensitive Geiger counter to see if there's any life left in the radium.
> Or you could expose the watch to a photomultiplier in total darkness to
> see if it scintillates.
>
> In other words, it doesn't burn out.
>
> Bill Hawkins