Related Experiment Video
Updated: Oct 26, 2025

Preparing an Isotopically Pure 229Th Ion Beam for Studies of 229mTh
Published on: May 3, 2019
Half-life of 51Mn
Stephen A Graves1, Paul A Ellison1, Hector F Valdovinos1
1Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin 53705, USA.
Abstract:
The half-life of 51Mn was measured by serial gamma spectrometry of the 511-keV annihilation photon following decay by β + emission. Data were collected every 100 seconds for 100,000-230,000 seconds within each measurement (n = 4). The 511-keV incidence rate was calculated from the 511-keV spectral peak area and count duration, corrected for detector dead time and radioactive decay. Least-squares regression analysis was used to determine the half-life of 51Mn while accounting for the presence of background contaminants, notably 55Co. The result was 45.59 ± 0.07 min, which is the highest precision measurement to date and disagrees with the current Nuclear Data Sheets value by over 6σ.
Related Concept Videos
Radioactive Decay and Radiometric Dating
Nuclear Stability
To hold positively charged protons together...
Half-life of a Reaction
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...
Nuclear Transmutation
Types of Radioactivity
Alpha (α) decay is the emission of an α particle from the nucleus. For example, polonium-210 undergoes α decay:

