It wasn't crucial to your point that the physics models predict their decay accurately and that if the claims of creationists were accurate, the decay rates would be wildly different.<quoted text>
I was wrong about the smoke detectors, which Polymath politely corrected me on-- it was Americium, not Californium.
Both are artificially created by engineers. I think they use linear accelerators and bombard other metals with high energy particles to get them to transform to Americium, but I'm far from certain about that.
I love that it's in everyday household safety devices.