An experimental setup for studying the Compton scattering of annihilation photons in various (entangled and decoherent) quantum states is presented. Two entangled γ-quanta with an energy of 511 keV and mutually orthogonal polarizations are produced by positron-electron annihilation in a thin aluminum plate and are emitted in opposite directions. To measure both photons, the setup provides two equivalent arms of Compton polarimeters. A Compton polarimeter consists of a plastic scintillation scatterer and an array of NaI(Tl) detectors for measuring photons deflected at an angle of 90°. The intermediate scatterer of the GAGG scintillator with SiPM readout is inserted into one of the arms to create a tagged decoherence process prior to the measurement of annihilation photons in polarimeters. The performance of Compton scatterers and NaI(Tl) counters is discussed. The polarization modulation factor and the analyzing power of Compton polarimeters are evaluated from the angular distributions of scattered gammas. The Compton scattering of photons in entangled and decoherent states is compared reliably for the first time.

A feasibility study has been performed in order to investigate the performance of the HADES  detector to measure the electromagnetic decays of the hyperon resonances $$\Sigma (1385)^{0}$$ Σ ( 1385 ) 0 ,  $$\Lambda (1405)$$ Λ ( 1405 )   and $$\Lambda (1520)$$ Λ ( 1520 )   as well as the production of double strange baryon systems $$\Xi ^{-}$$ Ξ -  and $$\Lambda $$ Λ $$\Lambda $$ Λ  in p + p reactions at a beam kinetic energy of $$4.5\,{\mathrm{GeV}}$$ 4.5 GeV . The existing HADES  detector will be upgraded by a new Forward Detector, which extends the detector acceptance into a range of polar angles that plays a crucial role for these investigations. The analysis of each channel is preceded by a consideration of the production cross-sections. Afterwards the expected signal count rates using a target consisting of either liquid hydrogen or polyethylene are summarized.

The experimental setup to study the difference between Compton scattering of entangled and decoherent annihilation photons is discussed. The pairs of entangled gammas are born in electron-positron annihilation at rest. The polarization state of each photon in such a pair is not definite and represents the superposition of horizontal and vertical polarizations, while the relative polarizations of the photons are orthogonal. After interaction with the environment (for example, via the Compton scattering) the entangled pair of photons is broken and the pair becomes decoherent with determined polarizations of both gammas. Since the Compton scattering depends on the polarization of the initial photon, the scattering kinematics of entangled and decoherent photons might be quite different. At present, there is no experimental comparison of the Compton scattering kinematics for entangled and decoherent gammas.

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It is proposed to replace existing Zero Degree Calorimeter of the BM@N setup at the Nuclotron (JINR) by a new forward hadron calorimeter for the measurement of the collision centrality and reaction plane orientation in heavy ions experiments. This calorimeter with transverse and longitudinal segmentation will be assembled from modules presently constructed for FHCal MPD and PSD CBM. The proposed design of the new calorimeter, simulation results for centrality and reaction plane determination by the new calorimeter, as well as radiation doses in the calorimeter simulated by FLUKA are discussed. The performance of hadron calorimeter supermodule studied at CERN is shown.