The production of exclusive events in proton–proton collisions at a centre-of-mass energy of 13 TeV is measured with the ATLAS detector at the LHC, using data corresponding to an integrated luminosity of 3.2 fb−1. The measurement is performed for a dimuon invariant mass of . The integrated cross-section is determined within a fiducial acceptance region of the ATLAS detector and differential cross-sections are measured as a function of the dimuon invariant mass. The...
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Significant results of scientific activity in year 2018
Cold dark matter is a crucial constituent of the current concordance cosmological model. Having avanishing equation of state (EOS), its energy density scales with the inverse cosmic volume and is thusuniquely described by a single number, its present abundance. We test the inverse cosmic volume law fordark matter (DM) by allowing its EOS to vary independently in eight redshift bins in the rangez¼105andz¼0. We use the latest measurements of the cosmic microwave background...
New lactic acid derivatives have been prepared and studied and found that they form cholesteric phase with the helix pitch length in interval 120–200 nm within a broad temperature range. Due to the positive dielectric anisotropy and the short pitch, the applied electric field causes reversible optical changes in planar cell, in which the applied electric field reorients the long molecular axis. Presence of short pitch and possibility to effectively affect electro-optical...
Antiferroelectrics are of interest due to their high potential for energy storage. Here, we report the discovery of pinched, polarization-vs.-electric field (P–E) hysteresis loops in the lead-free tungsten bronze ferroelectrics Ba4Sm2Ti4Nb6O30 and Ba4Eu2Ti4Nb6O30, while a broad, single P–E hysteresis loop was observed in the analogue compound Ba4Nd...
The three-dimensional distribution of the x-ray diffuse scattering intensity of BaTiO3 has been recorded in a synchrotron experiment and simultaneously computed using molecular dynamics simulations of a shell model. Together, these have allowed the details of the disorder in paraelectric BaTiO3 to be clarified. The narrow sheets of diffuse scattering, related to the famous anisotropic longitudinal correlations of Ti ions, are shown to be caused by...
Recent macroscopic experimental and theoretical evidence on the stress-strain-temperature behavior of NiTi beyond the strain recoverability limits (large strain, high stress, high temperature), where reversible martensitic transformation tends to proceed together with irreversible plastic deformation processes, is reviewed. Model predictions on the transformation – plasticity coupling are laid out based on the mathematical theory of martensitic microstructures and the...
A composite of powders of semi-Heusler ferromagnetic shape memory and pure titanium was successfully prepared by spark plasma sintering at the temperature of 950 °C. Sintering resulted in the formation of small precipitates and intermetallic phases at the heterogeneous interfaces. Various complementary experimental methods were used to fully characterize the microstructure. Imaging methods including transmission and scanning electron microscopy with energy dispersive X-...
Nucleation is the limiting step for thermodynamic phase transitions. While classical models predict that nucleation should be extremely rare, nucleation is surprisingly rapid in the gas-phase synthesis of diamond, silicon, and other industrial materials. We developed an approach for measuring nucleation landscapes using atomically defined precursors and find that diamond critical nuclei contain no bulk atoms, which leads to a nucleation barrier that is four orders of...
Due to its high sensitivity to corrosion, the use of Si in direct photoelectrochemical (PEC) water-splitting systems that convert solar energy into chemical fuels has been greatly limited. Therefore, the development of low-cost materials resistant to corrosion under oxidizing conditions is an important goal toward a suitable protection of otherwise unstable semiconductors used in PEC cells. Here, we report on the development of a protective coating based on thin and...
While quasicrystals possess long-range orientational order they lack translation periodicity. Considerable advancements in the elucidation of their structures and formative principles contrast with comparatively uncharted interrelations, as studies bridging the spatial scales from atoms to the macroscale are scarce. Here, we report on the homogeneous nucleation of a single quasicrystalline seed from the undercooled melt of glass-forming NiZr and its continuous growth into...
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Institute and media
Velké významné infrastruktury, 22.11.2019.
This year marks the...
Uniwersytet Opolski 21.10.2019.
J. Krása (Institute of Physics...
Ferroelectrics, 11.2.2019.
It is with much pleasure that I...
Technologické centrum AV ČR, 11.10.2018.
Czech Liaison Office...