The physicochemical calculations of the required amount of the GTT grade goptalum catalyst of ozone decomposition and the pressure drop on the catalyst bed under the operating conditions of the gas systems of particle accelerators were presented. The results of calculations were compared with the experimental data obtained in the gas system of the ATLAS detector unit of the Large Hadron Collider. The obtained physicochemical data make it possible to optimize the parameters of ozone filter destructors and the amount of catalyst required for purification of gas mixtures from ozone in detector units of accelerators.

The experiment NA64 is aimed at a direct search for invisible decays of sub-GeV dark photons (A′). The main goal in 2016 was to probe a region of the A′ parameter space, particularly interesting for the explanation of the muon gμ − 2 anomaly. The status and results from two NA64 runs in July and October 2016, obtained, respectively, with 2.75×10 and 4×10 accumulated electron on target are reported. A feasibility study of the search for the X → e+e− decay of a new light X boson, which could explain a recently observed excess of e+e− events from excited Be transitions is also presented.