The use of ultra shallow distributions of dopant in silicon to realize source and drain extensions in CMOS devices requires the development of analytical techniques able to provide their quantitative characterization. Information like retained dopant fluence, depth distribution and damage evolution are of fundamental importance to tailor the ultra shallow p/n junctions. In this work a summary of a complementary approach developed within an European multi-laboratories consortium (ANNA) is reported. Results obtained with several techniques on arsenic ultra low energy (0.5-5 keV) implants in Si are described. The employed techniques were secondary ion mass spectrometry, grazing incidence x-ray fluorescence (with either conventional or synchrotron radiation excitation), neutron activation analysis, medium energy ion scattering, Z-contrast annular dark field scanning transmission electron microscopy and spectroscopic ellipsometry. The cross comparisons of dose measurements, dopant distribution and damage build-up behavior enabled a detailed characterization of the implanted samples and identified the overlap of information from each analytical techniques.