- #1
nmsurobert
- 288
- 36
I've been reading about decay chains and I have confused myself on how decay works.
Take a sample of 238U for example.. its half-life is 4.5 billion years. At that point half of the sample is now 238U and the other half is 206Pb.
But looking at a decay chain, (and maybe I am reading it wrong) it shows that the change from 238U to 234Th is 4.5 billion years. Are the other half lives in the chain are so short relative to first step that we are quickly left with half 238U and half 206Pb?
Anytime I see figures of this half life, only first first and last isotopes are shown. There is never a discussion about the series. I started reading about this because I wanted a physical answer to how do we know the half life of 232Th without using the decay formula.
This is the chain I've been looking at. http://hyperphysics.phy-astr.gsu.edu/hbase/Nuclear/radser.html#c3
Take a sample of 238U for example.. its half-life is 4.5 billion years. At that point half of the sample is now 238U and the other half is 206Pb.
But looking at a decay chain, (and maybe I am reading it wrong) it shows that the change from 238U to 234Th is 4.5 billion years. Are the other half lives in the chain are so short relative to first step that we are quickly left with half 238U and half 206Pb?
Anytime I see figures of this half life, only first first and last isotopes are shown. There is never a discussion about the series. I started reading about this because I wanted a physical answer to how do we know the half life of 232Th without using the decay formula.
This is the chain I've been looking at. http://hyperphysics.phy-astr.gsu.edu/hbase/Nuclear/radser.html#c3