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G. Smirnov

Publications and source records attributed to G. Smirnov.

15 recordsLinked to original sources
arXiv2022

Multiple scattering of channeled and non-channeled positively charged particles in bent monocrystalline silicon

We present the results of an experimental study of multiple scattering of positively charged high energy particles in bent samples of monocrystalline silicon. This work confirms the recently discovered effect of a strong reduction in the rms multiple scattering angle of particles channeled in the silicon (111) plane. The effect is observed in the plane orthogonal to the bending plane. We show in detail the influence of angular constraints on the magnitude of the effect. Comparison of the multiple scattering process at different energies indicates a violation of the law of inverse proportionality of the rms angle of channeled particles with energy. By increasing the statistics, we have improved the results of multiple scattering measurements for particles moving, but not channeled, in silicon crystals.

physics.acc-ph↗
arXiv2018

Demonstration of MeV-Scale Physics in Liquid Argon Time Projection Chambers Using ArgoNeuT

MeV-scale energy depositions by low-energy photons produced in neutrino-argon interactions have been identified and reconstructed in ArgoNeuT liquid argon time projection chamber (LArTPC) data. ArgoNeuT data collected on the NuMI beam at Fermilab were analyzed to select isolated low-energy depositions in the TPC volume. The total number, reconstructed energies and positions of these depositions have been compared to those from simulations of neutrino-argon interactions using the FLUKA Monte Carlo generator. Measured features are consistent with energy depositions from photons produced by de-excitation of the neutrino's target nucleus and by inelastic scattering of primary neutrons produced by neutrino-argon interactions. This study represents a successful reconstruction of physics at the MeV-scale in a LArTPC, a capability of crucial importance for detection and reconstruction of supernova and solar neutrino interactions in future large LArTPCs.

hep-ex↗
arXiv2018

Peak Effects in Stable Linear Difference Equations

We consider asymptotically stable scalar difference equations with unit-norm initial conditions. First, it is shown that the solution may happen to deviate far away from the equilibrium point at finite time instants prior to converging to zero. Second, for a number of root distributions and initial conditions, exact values of deviations or lower bounds are provided. Several specific difference equations known from the literature are also analyzed and estimates of deviations are proposed. Third, we consider difference equations with non-random noise (i.e., bounded-noise autoregression) and provide upper bounds on the solutions. Possible generalizations, e.g., to the vector case are discussed and directions for future research are outlined.

eess.SY↗
arXiv2017

A hydrodynamic model approach to the formation of plasmonic wakes in graphene

Using the hydrodynamic model in the electrostatic approximation, we describe the formation of graphene surface plasmons when a charge is in motion either perpendicular or parallel to a graphene sheet. In the first case, the electron-energy loss (EEL) spectrum of the electron is computed, showing that the resonances in the spectrum are linked to the frequency of the graphene surface plasmons. In the second case, we discuss the formation of plasmonic wakes due to the dragging of the surface plasmons induced by the motion of the charge. This effect is similar to Coulomb drag between two electron gases at a distance from each other. We derive simple expressions for the electrostatic potential induced by the moving charge on graphene. We find an analytical expression for the angle of the plasmonic wake valid in two opposite regimes. We show that there is a transition from a Mach-type wake at high speeds to a Kelvin-type wake at low ones and identify the Froude number for plasmonic wakes. We show that the Froude number can be controlled externally tunning both the Fermi energy in graphene and the dielectric function of the environment, a situation with no parallel in ship wakes. Using EEL we propose a source of graphene plasmons, based on a graphene drum built in a metallic waveguide and activated by an electron beam created by the tip of an electronic microscope. We also introduce the notion of a plasmonic billiard.

cond-mat.mes-hall↗
arXiv2016

Scattering of surface plasmon-polaritons in a graphene multilayer photonic crystal with inhomogeneous doping

The propagation of a surface plasmon-polariton along a stack of doped graphene sheets is considered. This auxiliary problem is used to discuss: (i) the scattering of such a mode at an interface between the stack and the vacuum; (ii) the scattering at an interface where there is a sudden change of the electronic doping. The formalism is then extended to the {\it barrier problem}. In this system rich physics is found for the plasmonic mode, showing: total reflection, total transmission, Fabry-Pérot oscillations, and coupling to photonic modes.

cond-mat.mes-hall↗
arXiv2015

Vector variational problem with knitting boundary conditions

We consider a variational problem with a polyconvex integrand and nonstandard boundary conditions that can be treated as minimization of the stress energy during the suturing process in the plastic surgery. Ex- istence of minimizers is proved as well as necessary optimality conditions are discussed.

math.AP↗
arXiv2015

Renormalization of nanoparticle polarizability in the vicinity of a graphene-covered interface

We study the electromagnetic properties of a metamaterial consisting of polarizable (nano)particles and a single graphene sheet placed at the interface between two dielectrics. We show that the particle's polarizability is renormalized because of the electromagnetic coupling to surface plasmons supported by graphene, which results in a dispersive behavior, different for the polarizability components corresponding to the induced dipole moment, parallel and perpendicular to the graphene sheet. In particular, this effect is predicted to take place for a metallic particle whose bare polarizability in the terahertz (THz) region is practically equal to the cube of its radius (times $4π\varepsilon_0$). This opens the possibility to excite surface plasmons in graphene and enhance its absorption in the THz range by simply using a monolayer of metallic particles randomly deposited on top of it, as we show by explicit calculations.

cond-mat.mes-hall↗
arXiv2013

Probing spatial correlations in a system of polarizable particles via measuring its optical extinction spectrum

It is shown that quantitative information on spatial correlations in a system of polarizable particles can be extracted directly from its experimentally measurable optical spectra. For a collection of metallic nanoparticles (NPs), it is demonstrated that the degree of short-range correlation in NP's positions can be evaluated by an appropriate numerical analysis of the extinction spectrum in the surface plasmon resonance region, given the polarizability of an individual NP. The spectrum analysis consists in the evaluation of a single number, which is the derivative of the ensemble response function in the vanishing polarizability limit, to be compared to pre-calculated values for a model NP system with given density and correlation parameters.

cond-mat.mes-hall↗
arXiv2011

The UA9 experimental layout

The UA9 experimental equipment was installed in the CERN-SPS in March '09 with the aim of investigating crystal assisted collimation in coasting mode. Its basic layout comprises silicon bent crystals acting as primary collimators mounted inside two vacuum vessels. A movable 60 cm long block of tungsten located downstream at about 90 degrees phase advance intercepts the deflected beam. Scintillators, Gas Electron Multiplier chambers and other beam loss monitors measure nuclear loss rates induced by the interaction of the beam halo in the crystal. Roman pots are installed in the path of the deflected particles and are equipped with a Medipix detector to reconstruct the transverse distribution of the impinging beam. Finally UA9 takes advantage of an LHC-collimator prototype installed close to the Roman pot to help in setting the beam conditions and to analyze the efficiency to deflect the beam. This paper describes in details the hardware installed to study the crystal collimation during 2010.

physics.acc-ph↗
arXiv2008

The time-delay of the gravitationally lensed double quasar UM 673

The paper has been withdrawn because double checking and comparison with other data sets after the original submission showed that a broken R-band filter at the Maidanak telescope had affected our quasar monitoring observations in the years 2004 and 2005. They had led to partially spurious measurements, hence our original analysis and conclusions are not reliable.

astro-ph↗
arXiv2008

Systematic study of trace radioactive impurities in candidate construction materials for EXO-200

The Enriched Xenon Observatory (EXO) will search for double beta decays of 136Xe. We report the results of a systematic study of trace concentrations of radioactive impurities in a wide range of raw materials and finished parts considered for use in the construction of EXO-200, the first stage of the EXO experimental program. Analysis techniques employed, and described here, include direct gamma counting, alpha counting, neutron activation analysis, and high-sensitivity mass spectrometry.

physics.ins-det↗
arXiv2003

Approximate Solutions of Quantum Equations for Electron Gas in Plasma

We have obtained the solutions of linearized Shr{ö}dinger equation for spherically and axially symmetrical electrons density oscillations in plasma in the approximation of the self-consistent field. It was shown that in the center or on the axis of symmetry of such a system the static density of electrons can enhance, which leads to the increasing of density and pressure of ion gas. We suggest that this mechanism could be realized in nature as rare phenomenon called the 'fireball' and could be used in carrying out the research concerning controlled fusion.

physics.plasm-ph↗
arXiv2002

Induced radioactivity problem for high-power heavy-ion accelerators - Experimental investigation and longtime predictions

Preliminary results on activation and dose rates of thick copper targets irradiated with carbon ions at 0.1 GeV/A measured at the SIS-18 facility of GSI, Darmstadt and on residual nuclide production cross sections from thin copper and cobalt targets irradiated with carbon ions at 0.2 GeV/A measured at the TWAC facility of ITEP, Moscow are presented and compared with calculations by the Dubna version of the cascade model for nucleus-nucleus interactions realized in the code CASCADE and by the Los Alamos version of the Quark-Gluon String Model code LAQGSM merged with the Generalized Evaporation Model code GEM2 by Furihata, LAQGSM+GEM2.

nucl-ex↗
arXiv1997

Scintillation proportional Xe counter with WLS fiber readout for low-energy X-rays

A gas Xe based scintillation proportional counter with cylindrical geometry and wavelength shifting (WLS) fiber readout for X-rays of energy 0.5 - 100 keV is proposed. With such a design large sizes and sensitive area of the counter with a fairly well uniformity is possible. The counter could be used for "dark matter" search and neutrino magnetic moment measurement and for detection of small amounts or traces of radioactive elements in substances or environment.

hep-ex↗