Improved measurement of the ⁴⁴Ti half-life from a 14-year long study

The half-life of ⁴⁴Ti was determined by following the decay of ⁴⁴Ti and ⁶⁰Co for 14 yr. Mixed sources containing ⁴⁴Ti and ⁶⁰Co and pure sources of ⁴⁴Ti and ⁶⁰Co were prepared and their γ-ray spectra were measured with a Ge spectrometer once or twice a year. Counts in the 1157.0-keV γ-ray photopeak of ⁴⁴Ti and the 1173.2- and 1332.5-keV γ-ray photopeaks of ⁶⁰Co were used for this measurement. From the decay of the ⁴⁴Ti and ⁶⁰Co activity ratios, the half-life of ⁴⁴Ti was determined. Using a value of 5.2711±0.0004 yr for ⁶⁰Co half-life, we determined the half-life of ⁴⁴Ti as 58.9±0.3 yr. Special efforts were made to check for systematic errors and these were found to be negligible within the quoted uncertainty.