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Fredholm integral equations of the second kind are formulated to describe the anomalous skin effect in metal films on dielectric substrates. An algorithm is developed for numerical solution of the equations based on the quadrature method. As a result of its use for processing published experimental data on the spectral ellipsometry of gold films of different thicknesses on a silicon substrate, the density, relaxation time of the conduction electrons, and dielectric constant of gold are uniquely determined. The dependence of the dielectric constant of gold films on their thickness noted in a number of experimental studies is explained by using a model of the normal Drude skin effect that does not take the excitation of space charge in the film into account when solving the inverse optical problems. The optical fields in gold films are studied for different probabilities of mirror reflection of electrons from the boundary of the films It is found that in sensors for biological solutions with a Kretschmann configuration, structures in which the probability of mirror reflection of electrons from the metallic film–liquid interface approaches unity are to be preferred.

Data are presented on the adaptation of photonic doppler velocimetry (PDV) for gas-dynamic studies using guns. Measuring channels are time-matched via direct measurements of relative time corrections of PDV with an accuracy of up to 0.1 ns using the correlation analysis of the transit time of femtosecond pulses with different repetition periods through the measured fiber lines. The angle of impact of the projectile with the sample studied is determined using a linear regression method, which allows for the most complete use of the entire volume of experimental data and statistical determination of confidence intervals of the estimates obtained. Reliable recording of elastic wave parameters is carried out using a method of active-passive diagnostics of the PDV, which allows one to completely eliminate the interfering reference line and, accordingly, to increase the time and velocity resolution of the PDV.

A method for studying the accelerating effect of explosion products of condensed explosives is proposed and substantiated by calculations. This effect allows for a wide range of states on the isentrope of explosion products: from pressures and densities in the range of the Chapman–Jouguet state to a pressure of GPa and a density of g/cm . This method is applied to perform experimental studies of the accelerating effect of TG 25/75 explosion products, in which information on the movement of thin aluminum liners is recorded by a PDV multichannel heterodyne-interferometer.

A scheme of registration of displacements of reflecting surfaces by the method of laser ranging with the use of a device developed for measuring the delay of optical signal propagation is considered. Results of test experiments aimed at studying the ejecta and spallation fracture parameters of metals under shock wave loading with simultaneous applications of photonic Doppler velocimetry and laser ranging methods are reported.

Two devices intended for copper cylindrical liner gasdynamic acceleration to velocities of 5–7 km/s using the chemicals explosion energy have been investigated. It has been demonstrated that the acceleration of quasi-isentropically and isentropically loaded liners under the conditions of high-level dynamics, symmetry of deposition, and suppression of shock-induced dusting is feasible.

The GlueX experiment at Jefferson Laboratory aims to perform quantitative tests of non-perturbative QCD by studying the spectrum of light-quark mesons and baryons. A Detector of Internally Reflected Cherenkov light (DIRC) was installed to enhance the particle identification (PID) capability of the GlueX experiment by providing clean π /K separation up to 3.7 GeV/ c momentum in the forward region ( θ < 11°), which will allow the study of hybrid mesons decaying into kaon final states with significantly higher efficiency and purity. The new PID system is constructed with radiators from the decommissioned BaBar DIRC counter, combined with new compact photon cameras based on the SuperB FDIRC concept. The full system was successfully installed and commissioned with beam during 2019/2020. The initial PID performance of the system was evaluated and compared to one from Geant4 simulation.

The quasi-isentropic compressibility of a strongly nonideal helium plasma in the pressure range 250–600 GPa is experimentally studied in devices with cylindrical geometry. The temperature at the front of a cylindrical shock wave in helium ( T ≈ 10 000 K) and the flight speed of the inner cascade ( W ≈ 3.5 km/s), in the cavity of which the maximum compressed plasma density is achieved, are measured. Data on the compression of a nonideal helium plasma to a density ρ ≈ 3 g/cm 3 at an approximately constant final temperature of 21000 K are obtained. The trajectories of the metallic shells compressing the plasma are detected using high-power pulsed X-ray sources with a boundary electron energy of up to 60 MeV. The helium plasma density is determined using the radii of the shells measured at the time of their “stop.” The compressed plasma pressure is obtained using gasdynamic calculations. Comparative theoretical calculations of the quasi-isentropic compression parameters have been carried out using the following two theoretical models: the traditional chemical plasma model (SAHA code) and an ab initio quantum molecular dynamics (QMD) approach. No anomaly of the experimental data in the pressure range of the plasma phase transition theoretically assumed in helium is detected.

An Electron-Ion Collider (EIC) with center-of-mass energies √seN ∼ 20-100 GeV and luminosity L ∼ 1034 cm-2 s-1 would offer new opportunities to study heavy quark production in high-energy electron or photon scattering on protons and nuclei. We report about an R&D project exploring the feasibility of direct measurements of nuclear gluon densities at x >∼ 0.1 (gluonic EMC effect, antishadowing) using open charm production at EIC. We describe the charm production rates and angle-momentum distributions at large x and discuss methods of charm reconstruction using next-generation detector capabilities (π/K identification, vertex reconstruction). The results could be used also for other physics applications of heavy quark production at EIC (fragmentation functions, jets, heavy quark propagation in nuclei).

The proton is one of the main building blocks of all visible matter in the Universe 1 . Among its intrinsic properties are its electric charge, mass and spin 2 . These properties emerge from the complex dynamics of its fundamental constituents—quarks and gluons—described by the theory of quantum chromodynamics 3 – 5 . The electric charge and spin of protons, which are shared among the quarks, have been investigated previously using electron scattering 2 . An example is the highly precise measurement of the electric charge radius of the proton 6 . By contrast, little is known about the inner mass density of the proton, which is dominated by the energy carried by gluons. Gluons are hard to access using electron scattering because they do not carry an electromagnetic charge. Here we investigated the gravitational density of gluons using a small colour dipole, through the threshold photoproduction of the J / ψ particle. We determined the gluonic gravitational form factors of the proton 7 , 8  from our measurement. We used a variety of models 9 – 11 and determined, in all cases, a mass radius that is notably smaller than the electric charge radius. In some, but not all cases, depending on the model, the determined radius agrees well with first-principle predictions from lattice quantum chromodynamics 12 . This work paves the way for a deeper understanding of the salient role of gluons in providing gravitational mass to visible matter. The gluonic gravitational form factor of the proton was determined using various models, and these analyses showed that the mass radius of the proton was smaller than the electric charge radius.

. Jefferson Lab (JLab) 12 GeV energy upgrade provides a golden opportunity to perform precision studies of the transverse spin and transverse-momentum-dependent structure in the valence quark region for both the proton and the neutron. In this paper, we focus our discussion on a recently approved experiment on the neutron as an example of the precision studies planned at JLab. The new experiment will perform precision measurements of target Single-Spin Asymmetries (SSA) from semi-inclusive electro-production of charged pions from a 40 cm long transversely polarized 3 He target in deep-inelastic-scattering kinematics using 11 and 8.8 GeV electron beams. This new coincidence experiment in Hall A will employ a newly proposed solenoid spectrometer (SoLID). The large acceptance spectrometer and the high polarized luminosity will provide precise 4D ( x , z , P T and Q 2 ) data on the Collins, Sivers, and pretzelosity asymmetries for the neutron through the azimuthal angular dependence. The full 2 azimuthal angular coverage in the lab is essential in controlling the systematic uncertainties. The results from this experiment, when combined with the proton Collins asymmetry measurement and the Collins fragmentation function determined from the e + e - collision data, will allow for a quark flavor separation in order to achieve a determination of the tensor charge of the d quark to a 10% accuracy. The extracted Sivers and pretzelosity asymmetries will provide important information to understand the correlations between the quark orbital angular momentum and the nucleon spin and between the quark spin and nucleon spin.