The principal objective is to improve the knowledge of the nuclear data for 169-Yb decay, in particular, to determine, if possible with an uncertainty < 1 %, the photon emission probabilities of the main X- and y-rays. This radionuclide turns out to be a potential multiphoton standard for the calibration and characterisation of detectors in the low-energy region. In addition, it is of increasing interest in medicine for the preparation of brachytherapy sources for permanent or temporary interstitial implantations.
This determination will be carried out using the activity measurement combined with that of the photon emission fluxes. The activity will be measured by methods that are absolute or considered as such coincidence counting, well-type crystal method, liquid scintillation, etc. The photon emission fluxes will be measured with X- and gamma-ray spectrometers mainly with HP-Ge detectors, and possibly with Si-Li detectors for the very low-energy region.
The participants will be requested to measure at least one of the quantities, activity or flux. For this, there will be available point sources of known masses and/or solutions if they wish to prepare their own samples. In addition, if they have a coaxial-type germanium detector, they will be requested to report the count rates observed with the samples for this detector.
LPRI will provide the samples. The European partners are agreed to open this exercise at few laboratories not belonging at EUROMET.