Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Nuclear Physics Data

Radionuclide Half-Life Measurements Made at NIST

M. P. Unterweger, D. D. Hoppes, and F. J. Schima
This database is a table of the half lives of 65 important radionuclides measured primarily with ionization chambers by the Radioactivity Group of NIST. The included half lives range from 10 minutes to 60.7 years.

Atomic Weights and Isotopic Compositions

J. S. Coursey, D. J. Schwab, and R. A. Dragoset
This database contains the isotopic compositions or abundances of those elements which have characteristic terrestrial compositions. Atomic weights and relative atomic masses are also available for elements 1 through 112, 114 & 116.


Created July 29, 2009, Updated November 26, 2019