Collection of medium-resolution gamma spectra of certified U reference materials

A collection of medium resolution gamma-ray spectra from well-characterized U certified reference materials has been recorded using LaBr3(Ce) (2.0" x 0.5") and CZT (500 mm3) detectors. Aiming to acquire the highest quality reference data, the spectra were measured for long acquisition times, ensuring very good counting statistics across potentially useful spectral intervals - up to 1.4 MeV for the CZT and up to 2.8 MeV for the LaBr3(Ce) detectors. The experimental setup assures that the measurement geometry is stable and reproducible, and that the spectra have minimum influence from background radiation and pile-up effects. The spectra are available at the data library of The international working group on gamma spectroscopy techniques for U and Pu isotopics. The spectra feed phase I of the U isotopic inter-comparison exercise jointly organized by the ESARDA NDA Working Group and IAEA.