[en] This work describes the outcomes of the COST Action-TU1301 “NORM4Building” intercomparison on the determination of natural radioactivity in ceramics. Twenty-two laboratories involved in the intercomparison are evaluated for their performance using robust statistics. The reference values of ²²⁶Ra (²¹⁴Bi and ²¹⁴Pb) are determined to be 122 ± 11 Bq kg⁻¹ and 124 ± 14 Bq kg⁻¹, respectively and in secular equilibrium in the uranium chain while the reference values of ²³²Th (²²⁸Ac) is determined to be 61 ± 6 Bq kg⁻¹ and that of ⁴⁰K was determined to be 955 ± 40 Bq kg⁻¹. Although the aim of the exercise was to determine the activity concentration of ²²⁶Ra, ²³²Th and ⁴⁰K and evaluation of the “Activity Concentration Index”, laboratories were asked to report complete characterization of natural radionuclides. The results of this exercise pointed out a good performance among laboratories since the percentage of the acceptable results were above 90% for the radionuclides of interest. Based on these results, considering the systematic rejection of the results reported from a few laboratories we emphasize the need for quality control procedures. - Highlights: • The intercomparison exercise on natural radionuclides in ceramics samples was organized. • The performance of 22 laboratories was evaluated using robust statistics. • The acceptable results for the activity concentration of ²²⁶Ra, ²³²Th and ⁴⁰ K were above 90%. • The activity concentration index was calculated and guidelines on the interpretation are given. • The systematics of non-acceptable results emphasize the importance of quality control tests.

[en] The feasibility of using certified reference materials for the full energy efficiency calibration of p-type coaxial high-purity germanium detectors for the determination of radioactivity in environmental samples is discussed. The main sources of uncertainty are studied and the contributions to the total uncertainty budget for the most intense gamma lines are presented. The correction factors due to self-absorption and true coincidence summing effects are discussed in detail. The calibration procedure is validated for natural and artificial radionuclide determination in different matrices through an internal cross-validation and through the participation in a world-wide open proficiency test. (author)

[en] The KamLAND and Borexino experiments have observed, each at ∼4σ level, signals of electron antineutrinos produced in the decay chains of thorium and uranium in the Earth's crust and mantle (Th and U geoneutrinos). Various pieces of geochemical and geophysical information allow an estimation of the crustal geoneutrino flux components with relatively small uncertainties. The mantle component may then be inferred by subtracting the estimated crustal flux from the measured total flux. We find that crust-subtracted signals show hints of a residual mantle component, emerging at ∼2.4σ level by combining the KamLAND and Borexino data. The inferred mantle flux, slightly favoring scenarios with relatively high Th and U abundances, within ∼1σ uncertainties is comparable to the predictions from recent mantle models