What is Reference Source Method for Half Life Determination?
Half life determination: Part 3
Determination of t1/2 ~10^9 years or more by Reference source method
Reference source method (t1/2 ratio method) Parker, J. L. (1990)
Half life of 147Sm was obtained by Kajan, Ivan et al (2021) using the radionuclide 232Th, whose half life was known earlier. Relative counting rates of both the radioisotope was obtained. Activity ratio of them was known. Using the t1/2 of 232Th as 1.41 x 10^10 years, 147Sm's half life was obtained as 1.06(±0.02) x 10^11 years. .
A0 and A are the activity of the radioisotope 1 or 2 at time t = 0 and t = t. t1/2 of radioisotope is known. From the slope of plot of ln A2/A1 vs t , λ2 can be obtained easily. From λ2, t1/2 of 2nd radioisotope can be obtained easily. Reference source method (Parker, J. L. (1990) et al).
Advantage
Simple
Most suitable for gamma emitters
Disadvantage
Difficult to obtain data for pure beta emitters due to continious nature of the spectrum
Reference
Kajan, Ivan, Stefaan Pommé, Krzysztof Pelczar, and
Stephan Heinitz. "Measurement of the 145Sm half-life." Applied Radiation
and Isotopes 178 (2021): 109978..
Parker, J. L. (1990). Near-optimum procedure for half-life measurement by high-resolution gamma-ray spectroscopy. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 286(3), 502-506.
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