Results from the 169Yb exercise EUROMET action 410

An international comparison 'EUROMET action no 410' was organized with the objective of improving the knowledge of nuclear data for 169Yb decay. To determine the photon emission probabilities, the participants were asked to measure at least one of the quantities, activity per unit mass and/or photon emission rate per unit mass. In addition, the participants were requested to report the count rates observed with point source samples for an eventual coaxial-type germanium detector characterization. Eleven laboratories participated giving one or more sets of results. In all, 34 sets of results were received, 17 for the activity measurement, 11 for the photon emission rate measurement and 6 for the detector characterization. Using the accurate activity value obtained from this exercise, it was possible to determine the emission probabilities of the main X- and gamma rays with an uncertainty of $1 to 2 /%$ for the LX-rays, $1 /%$ for the KX-rays and $< 0.5 /%$ for the main gamma rays. These data can be very useful for the calibration of so-called 'gamma-X ray detectors'. The measurement of 169Yb with type P or N coaxial structure detectors has also made possible an estimation of the diameters and volumes. (authors)