Half-life of 67Cu

The half-life of Cu-67 was determined through serial gamma-ray spectrometry measurements of the dominant gamma emission (E (gamma) : 184.6 keV; branching ratio: 48.7%) produced following beta- decay. Data were collected consecutively for 1000 s per measurement, with a total of 3063 measurements over the duration of 36 days. The incidence rate for the 184.6 keV gamma-ray was determined from the spectral peak area and duration of each measurement. This rate was then corrected to account for detector dead-time, radioactive decay during each acquisition and drift in the computer clock in comparison to NIST nuclear clock. Least-squares regression analysis was performed to determine the half-life of Cu-67. The result was 61.761 +/- 0.004 h, which is the highest precision measurement to date, and marks a 24-fold precision improvement over the current Nuclear Data Sheets value.