The European NORM Association (ENA)-promoting radiation protection in the field of norm in Europe.

The European NORM Association (ENA) was founded in 2017, merging previously informal European networks. It has the statute of an International Non-profit Organization established under Belgian Law. The objective of ENA is to promote and advance radiation protection in the context of exposure to NORM. It operates as a European platform and forum for discussion, dissemination and exchange of information, training and education and by supporting scientific knowledge and new directions of research related to NORM issues. A key activity of ENA is to share practical solutions. To this end, ENA gathers radiation protection practitioners, regulators, scientists and industry representatives in order to support the management of NORM in compliance with European standards and according to best practices. Since its foundation, ENA has organized three workshops where topical issues on NORM have been discussed. It has established close working relationships and links with IAEA, HERCA, IRPA and other international initiatives-getting a recognition at international level. ENA has set up working groups on NORM in the industry, in the environment, in building materials and, as recently as in 2021, a working group on decommissioning of NORM facilities. A series of webinars have been organized to present case studies on NORM decommissioning and discuss associated challenges and practical solutions.

Two-photon laser spectroscopy of antiprotonic helium and the antiproton-to-electron mass ratio.

Physical laws are believed to be invariant under the combined transformations of charge, parity and time reversal (CPT symmetry). This implies that an antimatter particle has exactly the same mass and absolute value of charge as its particle counterpart. Metastable antiprotonic helium (pHe(+)) is a three-body atom consisting of a normal helium nucleus, an electron in its ground state and an antiproton (p) occupying a Rydberg state with high principal and angular momentum quantum numbers, respectively n and l, such that n ≈ l + 1 ≈ 38. These atoms are amenable to precision laser spectroscopy, the results of which can in principle be used to determine the antiproton-to-electron mass ratio and to constrain the equality between the antiproton and proton charges and masses. Here we report two-photon spectroscopy of antiprotonic helium, in which p(3)He(+) and p(4)He(+) isotopes are irradiated by two counter-propagating laser beams. This excites nonlinear, two-photon transitions of the antiproton of the type (n, l) → (n - 2, l - 2) at deep-ultraviolet wavelengths (λ = 139.8, 193.0 and 197.0 nm), which partly cancel the Doppler broadening of the laser resonance caused by the thermal motion of the atoms. The resulting narrow spectral lines allowed us to measure three transition frequencies with fractional precisions of 2.3-5 parts in 10(9). By comparing the results with three-body quantum electrodynamics calculations, we derived an antiproton-to-electron mass ratio of 1,836.1526736(23), where the parenthetical error represents one standard deviation. This agrees with the proton-to-electron value known to a similar precision.