Experimental half-life determination of 176Lu

• The half-life of 176Lu was determined by ICP-OES, ICP-HRMS and LSC.
• The LSC efficiency was determined with the CIEMAT/NIST method.
• The half-life was found to be 3.640(35)×1010 y.

The half-life of the naturally occurring long-lived rare earth isotope 176Lu was determined by a combination of highly sophisticated experimental procedures in order to further improve the reliability and the precision of literature data. The amount of lutetium in the samples was determined by inductively coupled plasma optical emission spectrometry (ICP-OES) using a NIST reference standard. The isotopic ratio N(176Lu)/N(Lu) in the samples was measured by means of inductively coupled plasma high resolution mass spectrometry (ICP-HRMS). The activity divided by the mass of Lu was determined by applying liquid scintillation (LS) counting. The LS counting efficiency of the beta/gamma emitter 176Lu was determined with the CIEMAT/NIST efficiency tracing technique with low uncertainty. The influences of colour quenching and background effects are discussed in this paper. The half-life was found to be 3.640(35)×1010 y. The result is in good agreement with other evaluations and the relative standard uncertainty of 0.95% is among the lowest of previously published data.