Calorimetric measurements of the half life of plutonium-240

Analysis of the atmospheric 14C record spanning the past 50,000 years derived from high-precision 230Th/234U/238U, 231Pa/235U and 14C dates on fossil corals

“…The half-life of 240 Pu has been reported as ''6552.471.7 years'' by calorimetry (Rudy et al, 1984), ''657476.2 years'' by mass spectrometry (Strohm, 1984), and ''6571717.5 years'' (Steinkruger et al, 1984) and ''6552.2713.8 years'' (Lucas andNoyce, 1984) by a-particle counting. The estimates suggest no systematic offset observed among different types of instruments, and demonstrate that calorimetry, as well as other methods, can provide very high-precision and high-accuracy measurements.…”

“…Another advantage of calorimetry is that a large amount of radioactive material may be directly measured without introducing errors resulting from diluting the original material to a lower radioactive level (sometimes by a factor of 10 8 ; Mann et al, 1961), which is required by the ionization counting system. The elegance of the calorimetry experimental design greatly reduces the introduction of systematic errors, and this is a prime reason why it is widely used for various applications (Rudy et al, 1984;Mann and Unterweger, 1995;Colle´and Zimmerman, 2001;Stump et al, 2005). While constant source, counting geometry, dead-time correction and discrimination levels have to be all considered within a gas counting system, the source of calorimetry can be enclosed in the glass or metal container and simply measured by its power output (Ramthun, 1973).…”