Explore the vast range of titles available.

We report a study of optical and scintillation properties of modules of a prototype electromagnetic calorimeter based on barium fluoride crystals (BaF 2 ) measuring 25 × 25 × 160 mm 3 . The length of the crystal radiator of the calorimeter is optimized using the Monte Carlo method in order to improve its energy resolution. Homogeneity of the light output from different sections of the module using gamma quanta from a 137 Cs source is demonstrated. The scintillation time of the crystal module under gamma excitation is measured.

We report simulation and resolution evaluation of monolithic position sensitive detectors with different surfaces. The best result was obtained using a combination of rough polishing of the crystal surface and a Teflon wrapper with a resolution in the interaction depth of dZ = 0.89 ± 0.01 mm. The best planar resolution dX = 0.53 ± 0.01 mm is obtained for a finely polished plate with an ESR film. The diffuse reflector also demonstrates an increase in light collection by 33% compared to the specular one.

New YAG:Yb:Mg and YAG:Yb:Ca:Mg crystals with a short decay time are grown for the first time using the Czochralski method. The pulsed cathodoluminescence spectra of the new scintillators, their light output, and decay time are studied. The light output of the YAG:Yb:Mg and YAG:Yb:Ca:Mg crystals are found to be 460 and 770 photons/MeV, respectively. It is shown that the decay time spectra of the new crystals are described by two components: 1.57/8.5 ns for YAG:Yb:Mg and 1.52/7.79 ns for YAG:Yb:Ca:Mg.

For the first time, new YAG:Yb:Ca and YAG:Yb:Ca:Si crystals with ultrafast scintillation time are grown. The crystals are grown by the Czochralski method. The spectra of pulsed cathodoluminescence of new scintillators, light yield, and their scintillation time are studied. It was shown that the time constant of scintillation pulse decay of YAG:Yb:Ca and YAG:Yb:Ca:Si crystals is 1.48 ns and 1.15 ns, respectively.

The spectra and decay time of pulsed cathodoluminescence (PCL) of a scintillating crystals excited by the electron beam is compared to the spectra and decay time of the luminescence of the same crystals initiated by γ-rays (GL). It is shown that spectra and decay time of PCL and GL are identical within the experimental errors. The explanation of these results is based on taking into account the physical processes within the crystal media under the irradiation by high-energy particles. The results of this study confirm that the PCL method may be used for the rapid analysis of the luminescent properties of scintillators.

Charmonium production cross-section in proton–proton collisions is measured at the centre-of-mass energy s = 13 TeV using decays to p p ¯ final state. The study is performed using a data sample corresponding to an integrated luminosity of 2.2 fb - 1 collected in 2018 with the LHCb detector. The production cross-section of the η c meson is measured in a rapidity range of 2.0 < y < 4.0 and in a transverse momentum range of 5.0 < p T < 20.0 GeV / c , which is extended compared with previous LHCb analyses. The differential cross-section is measured in bins of p T and, for the first time, of y . Upper limits, at 90% and 95% confidence levels, on the η c ( 2 S ) and h c ( 1 P ) prompt production cross-sections are determined for the first time.

We report on a measurement of Spin Density Matrix Elements (SDMEs) in hard exclusive ρ 0 meson muoproduction at COMPASS using 160 GeV/ c polarised μ + and μ - beams impinging on a liquid hydrogen target. The measurement covers the kinematic range 5.0 GeV/ c 2 < W < 17.0 GeV/ c 2 , 1.0 (GeV/ c ) 2 < Q 2 < 10.0 (GeV/ c ) 2 and 0.01 (GeV/ c ) 2 < p T 2 < 0.5 (GeV/ c ) 2 . Here, W denotes the mass of the final hadronic system, Q 2 the virtuality of the exchanged photon, and p T the transverse momentum of the ρ 0 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 ( γ T ∗ → V L ) indicate a violation of s -channel helicity conservation. Additionally, we observe a dominant contribution of natural-parity-exchange transitions and a very small contribution of unnatural-parity-exchange transitions, which is compatible with zero within experimental uncertainties. The results provide important input for modelling Generalised Parton Distributions (GPDs). In particular, they may allow one to evaluate in a model-dependent way the role of parton helicity-flip GPDs in exclusive ρ 0 production.

We have measured the polarization of ΛΛ hyperons produced inclusively by a Σ−⁻Σ− beam of 340 GeV/c momentum in nuclear targets. From a sample of 9.5 millions of identified ΛΛ decays, polarizations were determined in the range xF>0.1x_(F) 0.1xF​>0.1 and pt≤1.6p_(t) 1.6pt​≤1.6 GeV/c . The polarization w.r.t. the production normal is mainly positive for xF≥0.3x_(F) 0.3xF​≥0.3. At fixed values of xFx_(F)xF​, it increases with ptp_(t)pt​ to a maximum between pt=0.5p_(t) = 0.5pt​=0.5 and pt=1p_(t) = 1pt​=1 GeV/c , and then decreases to zero or even negative values, in sharp contrast to the plateau above pt=1p_(t) = 1pt​=1 GeV/c observed in inclusive ΛΛ production by protons.

We have measured the polarization of Ξ− hyperons produced inclusively by a Σ− beam of 340 GeV/c momentum in nuclear targets. From a sample of 880000 identified Ξ− decays, polarizations were determined in the range 0 < x F < 0.9 and pt≤1.6 GeV/c. The polarization w.r.t. the production normal is negative for xF≥ 0.3. At fixed values of x F , its magnitude increases with p t to maximum values which reach about 20% at large x F .

We report on a measurement of the differential cross sections of inclusiveK890±K^(₈)90K890±​production inσ−,pi−⁻, pi⁻σ−,pi−and ne. (Springer)