U238 and Half Life ```Name: Bec S. Status: student Age: 15 Location: N/A Country: N/A Date: 4/9/2003 ``` Question: Does uranium238 have the longest half life of all radioactive elements? Replies: Oh my, no. U-238's half-life is long, 4.51e9 y, but it is not the longest. Here is a list of nuclides with longer half-lives. ```V-50 6e15 y Rb-87 5e11 y Zr-96 >3.6e17 y Te-123 1.2e13 y Nd-144 5e15 y Sm-147 1.06e11 y Sm-148 1.2e13 y Sm-149 4e14 y Gd-152 1.1e14 y Lu-176 3e10 y Hf-174 2.0e15 y Ta-180 >1e13 y Re-187 7e10 y Pt-190 6e11 y Pt-192 1e15 y Th-232 1.41e10 y ``` The longest-lived of these is Zr-96, with a half-life nearly a hundred million times longer than U-238. Richard E. Barrans Jr., Ph.D. PG Research Foundation, Darien, Illinois U(238) has a long half life but not THE LONGEST. Some other grandfathers are: Th(232) t1/2 = 1.405x10^10 years, Lu(176) t1/2 = 3.78x10^10 years, Hf(174) t1/2 = 2x10^15 years I am not sure these are the longest, but you can scan the following web site for data in many forms: http://ie.lbl.gov/education/isotopes.htm Vince Calder Click here to return to the Physics Archives

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