halflives

[Les Slaback <lester.slaback@nist.gov>]

To be respond to what I think Ted intended to ask,  the latest compilation
of the best guesses based on all the published data is (at least on my
shelf) ...
  Table of Isotopes, Eighth Ed, Wiley-Interscience,  1996*
  Chart of the Nuclides, GE, 14th ed, 1989 (thru 4/88)
  ICRP 38, Radionuclide Transformations, 1983

The Brookhaven Nuclear Data Center also posts values, but I do not know the
schedule for updating their 'best' value determinations.

And note that these various folks frequently do not agree.

If there is a specific nuclide of interest and accuracy is critical you
need to do a lit search.  Ron Colle at NIST recently published several new
'best' values that differ significantly from the above compilations.

Also be aware that various standardizing labs, e.g., NIST, use their own
'best' values for particular nuclides which are identified with the source
documentation you get when you buy a standard.  But I have not seen these
collectively published anywhere (but they are all individually in the
literature).

* a personal observation - the CD-ROM version does not provide any search
advantages over the paper version, is certainly less convenient to read,
but is obviously more portable.
Disclaimer:  the above are the personal musings of the author, and do not
represent any past, present, or future position of NIST, the U.S. government,
or anyone else who might think that they are in a position of authority. 
Lester Slaback, Jr.  [Lester.Slaback@NIST.GOV] 
NBSR Health Physics 
Center for Neutron Research 
NIST
100 Bureau Dr.  STOP 3543 
Gaithersburg, MD  20899-3543 
301 975-5810 
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