Standardization and half-life measurement of 55Fe

Methods for measurement of the specific activity and the KX-ray emission rate per 1 g of a 55Fe solution are described. The emission rate was determined by a pressurized proportional 4π-counter with an uncertainty of 0.3% and absorption and self-absorption corrections were determined experimentally for each source. The specific activity of the 55Fe solution was determined with an uncertainty of 0.7% by the 4π KX-γ-coincidence tracing method with 54Mn as the tracer. 55Fe to 54Mn efficiency ratio equations were derived. The 55Fe half-life was measured in the pressurized proportional 4π-counter over a period of not, vert, similar2.5 half-lives. The result is 995±3 days.