Related Experiment Video
Updated: Mar 16, 2026

Preparing an Isotopically Pure 229Th Ion Beam for Studies of 229mTh
Published on: May 3, 2019
Comprehensive Review and Critical Evaluation of the Half-Life of Tritium
1National Institute of Standards and Technology, Gaithersburg, MD 20899-8462, U.S.A.
Abstract:
As part of the preparation and calibration of three new National Institute of Standards and Technology (NIST) tritiated-water radioactivity Standard Reference Materials (SRMs), we have performed a comprehensive review and critical evaluation of the half-life of tritium (hydrogen-3). Twenty three experimentally-determined values of the half-life of tritium, reported between 1936 and 2000, were found. Six of these values were updated by later values. Two values were limits. Two values were deemed to be outliers. The 13 remaining values were evaluated in several ways. The results are compared with the results of other recent evaluations and all are found to be in good agreement. Our final recommended value for the half-life of tritium is the average of the adopted values from the four most recent evaluations, (4500 ± 8) d, where 8 d corresponds to one standard uncertainty.
Related Concept Videos
Half-life of a Reaction
Radioactive Decay and Radiometric Dating
Nuclear Stability
To hold positively charged protons together...
Isotopes
An element's atomic mass, or weight,...
Isotopes and Radioisotopes
An isotope containing...
Atomic Nuclei: Types of Nuclear Relaxation
In spin–lattice or longitudinal relaxation, the excited spins exchange energy with the surrounding lattice as they return to the lower energy level. Among several mechanisms that contribute to spin–lattice relaxation, magnetic dipolar interactions are significant. Here, the excited nucleus transfers...

