New determination of the half-life ofU233

Experimental determination of the233U half-life

“…Adopting 360.2(3) kBq g −1 as the final activity J a ff e y e t a l. V a n in b ro u c k x e t a l. G e id e lm a n e t a l. A g g a rw a l e t a l. P o m m é e t a l. In table 5 and figure 2, the new half-life value derived from this work is compared with previously published values. The present value is somewhat lower than most of the precise measurements performed in the 1970s [1][2][3][4], as well as the ensuing reference value 1.592 (2) × 10 5 a. The difference with the latter amounts to 0.3%, which is about twice the combined standard uncertainty of the recommended value summed quadratically with our uncertainty.…”

“…The difference with the latter amounts to 0.3%, which is about twice the combined standard uncertainty of the recommended value summed quadratically with our uncertainty. The result is in good agreement with a few of the previously measured data, published as recalculated or preliminary versions by Jaffey et al [1] (see table 5): 1.590 (3)× 10 5 a by Bigham et al in 1958 (recalculated), 1.583 (7) × 10 5 a by Durham in 1969 (preliminary) and 1.585 (5) × 10 5 a by Euratom, Geel in 1973 (preliminary value, later increased by 0.47% [2]). Also the values 1.5885 (75) × 10 5 a by Aggarwal et al and 1.5911 (15) × 10 5 a by Jaffey et al agree well, considering that the uncertainty of the latter includes statistical scatter of the measurement results only.…”

“…Taking the data in [1][2][3][4] (incl. Bigham et al and Durham), one can calculate a partially weighted mean according to the procedure laid down in [33], leading to a new best estimate of T 1/2 ( 233 U) = 1.5903 (13) × 10 5 a.…”

“…Half-life measurements of long-lived uranium isotopes, such as 233 U [1][2][3][4], 235 U and 238 U [5], were carried out with high precision in the 1970s [6]. The current reference values for the half-life of these radionuclides [7,8] are still mainly based on these few experiments, as their high standard of quality may have discouraged other researchers in attempting to confirm or improve them.…”

“…The quoted uncertainty is merely based on the observed scatter of the measurement data and corresponds to the standard uncertainty of the mean. In 1976, Vaninbroukx et al [2] published a half-life value of 1.5925 (13) × 10 5 a. They combined measurements with a low-geometry counter, a liquid-scintillation counter and a 4π proportional counter to determine the specific activity of a large number of samples from two batches of uranium oxides.…”