RE: Half-life of Ra-228

[Rosen <rosen@radsafe.pitt.edu>]

Subject: Half-life of Ra-228

5.75 yr is the correct value. Interestingly, this is close to the value that
Madam Curie found. Several years later the half life was reevaluated and the
6.7 yr half life was measured. This was the value that persisted in the
literature through the 70's. The Rad Health Handbook was probably the only
reference source that persisted in using the incorrect value until the 3rd
edition of the Shleien, Slaback and Birky Handbook of HP and RH.

The abundance of K-40 and the half life of Ba-133 also have an interesting
histories, in terms of erroneous values being propogated through the
literature.

P.S. The RHH 

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