radiation decay

Suffice to say that radiation decay of a metal inside it measures time.

"All I have been able to determine is that the radiation decay is the same.

Spock looked at the radiation decay figures from the rocky debris.

The radiation decay products ionize genetic material, causing mutations that sometimes turn cancerous.

Specially designed machines bombard the suspect explosives with neutrons, and read the gamma radiation decay signatures to determine the chemical composition of the sample.

After that, it is a case of sorting out a signal from all the events due to cosmic rays, neutrinos, background radiation decay, and other assorted nasty interfering background.