233U half-life

The 233U half-life has been measured by the following method. A refined solution of a uranium salt, enriched by 233U, was used as a source. The concentration of the uranium was determined via potentiometric titration. The specific activity of uranium in the solution was measured by precision technique of 4πα-X coincidences. The resulting half-life was calculated using the following expression: T233=BK233(1+β+βγ)[1-B(K234(1+β+βγ)/T234+K235/T235+K238/T238)]-1, where B=CNsub(A)ln2/asub(mes)ΣKsub(i)Msub(i); C is the measured concentration of uranium in the refined solution; Ksub(i) is the isotopic content of uranium (at.%); Msub(i) are the atomic masses of uranium isotopes in the carbon scale; Tsub(i) are the half-life of the uranium isotopes; γ is the correction coefficient, which takes into account the storage of 228Th and 224Ra nuclides in the source; Nsub(A) is the Avogadro number; asub(mes) is the measured activity of α-emitting nuclides in the refined solution. The result obtained, T233=(1.5937+-0.0022)x105y, P=0.95, are in a good agreement with those of recent measurements. Different sources of systematic errors are evaluated. The total systematic error is, at the 95% confidence level, equal to 0.14%