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

The half-life of Ti-44 was determined by following the decay of Ti-44 and Co-60 for 14 yr. Mixed sources containing Ti-44 and Co-60 and pure sources of Ti-44 and Co-60 were prepared and their gamma-ray spectra were measured with a Ge spectrometer once or twice a year. Counts in the 1157.0-keV gamma-ray photopeak of Ti-44 and the 1173.2- and 1332.5-keV gamma-ray photopeaks of Co-60 were used for this measurement. From the decay of the Ti-44 and Co-60 activity ratios, the half-life of Ti-44 was determined. Using a value of 5.2711 +/- 0.0004 yr for Co-60 half-life, we determined the half-life of Ti-44 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.