We report on a measurement of Spin Density Matrix Elements (SDMEs) in hard exclusive $$\omega $$ ω meson muoproduction on the proton at COMPASS using 160 GeV/c polarised $$ \mu ^{+}$$ μ + and $$ \mu ^{-}$$ μ - beams impinging on a liquid hydrogen target. The measurement covers the range 5.0 GeV/$$c^2$$ c 2 $$< W<$$ < W < 17.0 GeV/$$c^2$$ c 2 , with the average kinematics $$\langle Q^{2} \rangle =$$ ⟨ Q 2 ⟩ = 2.1 (GeV/c)$$^2$$ 2 , $$\langle W \rangle = 7.6$$ ⟨ W ⟩ = 7.6  GeV/$$c^2$$ c 2 , and $$\langle p^{2}_{\mathrm{T}} \rangle = 0.16$$ ⟨ p T 2 ⟩ = 0.16  (GeV/c)$$^2$$ 2 . Here, $$Q^2$$ Q 2 denotes the virtuality of the exchanged photon, W the mass of the final hadronic system and $$p_T$$ p T the transverse momentum of the $$\omega $$ ω meson with respect to the virtual-photon direction. The measured non-zero SDMEs for the transitions of transversely polarised virtual photons to longitudinally polarised vector mesons ($$\gamma ^*_T \rightarrow V_L$$ γ T ∗ → V L ) indicate a violation of s-channel helicity conservation. Additionally, we observe a sizeable contribution of unnatural-parity-exchange (UPE) transitions that decreases with increasing W. The results provide important input for modelling Generalised Parton Distributions (GPDs). In particular, they may allow to evaluate in a model-dependent way the contribution of UPE transitions and assess the role of parton helicity-flip GPDs in exclusive $$\omega $$ ω production.

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Intensification of landscape use brings along the negative effects on environmental components. These include surface water pollution. The aim was to determine the effect of landscape use on the water quality of the Žitava river. It was assumed that an area with the high proportion of anthropogenic activity would negatively affect water quality. At the same time, we assumed that an area with the lower proportion of anthropogenic use and with the higher proportion of natural and semi-natural elements contributes to self-cleaning ability of the watercourse. At the four observed sites, ammoniacal nitrogen (NH4-N), nitrate-nitrogen (NO3-N), phosphate-phosphorus (PO4-P) and water conductivity were monitored. Landscape use was analysed using the database of land cover based on the CORINE Land Cover methodology. Subsequently, it was observed how the landscape use affects the water quality. It was found that the very good state, represented by the Class I water quality, is according to the measured indicators mostly present in the areas predominantly covered by forests along with extensive use of elements of the agricultural land. The area with predominance of agricultural and urbanised sites where the anthropogenic influence prevails is characterised by average water quality. As the overall water quality of the Žitava river reaches the average, it is necessary to eliminate the pollution by constructing the sewer systems in the villages through which the watercourse is passing and, in agriculture, to ensure the adherence to the legislation concerning the protection of surface water against pollution from agricultural sources.

We present a new data acquisition system for the COMPASS++/AMBER experiment designed as a further development of the Intelligent FPGA-based Data Acquisition framework. The system is designed to have a maximum throughput of 5 GB/s. We designed the system to provide free-running continuous readout which allows us to implement a sophisticated data filtering by delaying the decision until the hardware filter and high-level trigger stage which processes data. The system includes front-end cards, fully-digital hardware filter, data multiplexers, a timeslice builder, and a high-level trigger farm. The data selection and data assembly require a time structure of the data streams with different granularity for different detectors. We define a unit of detector data as image and combine images from different detectors within a time window to timesliceses. By routing data based on the timeslices we can average data rates and easily achieve scalability. The main component which allows us to achieve these goals is a high-performance and cost-effective hardware timeslice builder. The timeslice builder combines streaming data by their time and consists of the data switch and the spillbuffer build. The scalable architecture allows us to increase the throughput of the system and achieve a true triggerless mode of operation.