A. Kovalenko - Drafting Committee

A. Kovalenko
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A. Kovalenko
Drafting Committee

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Pub Categories

High Energy Physics - Experiment (18)
Physics - Instrumentation and Detectors (15)
Nuclear Experiment (15)
Instrumentation and Methods for Astrophysics (7)
High Energy Physics - Lattice (5)
Astrophysics (3)
Cosmology and Nongalactic Astrophysics (2)
Physics - Materials Science (2)
General Relativity and Quantum Cosmology (2)
Physics - Mesoscopic Systems and Quantum Hall Effect (1)
Physics - Accelerator Physics (1)
Physics - Medical Physics (1)
High Energy Physics - Phenomenology (1)
Computer Science - Computers and Society (1)
Physics - Soft Condensed Matter (1)
Physics - Space Physics (1)
Physics - Statistical Mechanics (1)
Physics - Fluid Dynamics (1)

Publications Authored By A. Kovalenko

Krypton-85 is an anthropogenic beta-decaying isotope which produces low energy backgrounds in dark matter and neutrino experiments, especially those based upon liquid xenon. Several technologies have been developed to reduce the Kr concentration in such experiments. We propose to augment those separation technologies by first adding to the xenon an 85Kr-free sample of krypton in an amount much larger than the natural krypton that is already present. Read More

A test of a cornerstone of general relativity, the gravitational redshift effect, is currently being conducted with the RadioAstron spacecraft, which is on a highly eccentric orbit around Earth. Using ground radio telescopes to record the spacecraft signal, synchronized to its ultra-stable on-board H-maser, we can probe the varying flow of time on board with unprecedented accuracy. The observations performed so far, currently being analyzed, have already allowed us to measure the effect with a relative accuracy of $4\times10^{-4}$. Read More

Belarusian State University is currently developing the educational and research web portal of nuclear knowledge BelNET (Belarusian Nuclear Education and Training Portal). In the future, this specialized electronic portal could grow into a national portal of nuclear knowledge. The concept, structure and taxonomy of BelNET portal are developed. Read More

Integral equation theory of molecular liquids based on statistical mechanics is quite promising as an essential part of multiscale methodology for chemical and biomolecular nanosystems in solution. Beginning with a molecular interaction potential force field, it uses diagrammatic analysis of the solvation free energy to derive integral equations for correlation functions between molecules in solution in the statistical-mechanical ensemble. The infinite chain of coupled integral equations for many-body correlation functions is reduced to a tractable form for 2- or 3-body correlations by applying the so-called closure relations. Read More

The COHERENT collaboration's primary objective is to measure coherent elastic neutrino-nucleus scattering (CEvNS) using the unique, high-quality source of tens-of-MeV neutrinos provided by the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL). In spite of its large cross section, the CEvNS process has never been observed, due to tiny energies of the resulting nuclear recoils which are out of reach for standard neutrino detectors. The measurement of CEvNS has now become feasible, thanks to the development of ultra-sensitive technology for rare decay and weakly-interacting massive particle (dark matter) searches. Read More

A unique test of general relativity is possible with the space radio telescope RadioAstron. The ultra-stable on-board hydrogen maser frequency standard and the highly eccentric orbit make RadioAstron an ideal instrument for probing the gravitational redshift effect. Large gravitational potential variation, occurring on the time scale of $\sim$24 hr, causes large variation of the on-board H-maser clock rate, which can be detected via comparison with frequency standards installed at various ground radio astronomical observatories. Read More

Affiliations: 1Drafting Committee, 2Drafting Committee, 3Drafting Committee, 4Drafting Committee, 5Drafting Committee, 6Drafting Committee, 7Drafting Committee, 8Drafting Committee, 9Drafting Committee, 10Drafting Committee

We propose to perform measurements of asymmetries of the Drell-Yan (DY) pairs production in collisions of non-polarized, longitudinally and transversally polarized protons and deuterons which provide an access to all leading twist collinear and TMD PDFs of quarks and anti-quarks in nucleons. The measurements of asymmetries in production of J/\Psi and direct photons will be performed as well simultaneously with DY using dedicated triggers. The set of these measurements will supply complete information for tests of the quark-parton model of nucleons at the QCD twist-two level with minimal systematic errors. Read More

We present the results of the first experimental study of ionization yield of electron recoils with energies below 100 keV produced in liquid xenon by the isotopes: 37Ar, 83mKr, 241Am, 129Xe, 131Xe. It is confirmed by a direct measurement with 37Ar isotope (2.82 keV) that the ionization yield is growing up with the energy decrease in the energy range below ~ 10 keV accordingly to the NEST predictions. Read More

Ultrafast laser excited hot electrons can transport energy supersonically far from the region where they are initially produced. We show that this ultrafast energy transport is responsible of the emission of coherent acoustic phonons deeply beneath the free surface of a copper metal sample. In particular we demonstrate that enough energy carried by these hot electrons over a distance as large as 220nm at room temperature in copper can be converted into coherent acoustic phonons. Read More

Resistance functions for two spherical particles with the Navier slip boundary condition in general linear flows, including rigid translation, rigid rotation, and strain, at low Reynolds number are derived by the method of reflections as well as twin multipole expansions. In the solutions, particle radii and slip lengths can be chosen independently. In the course of calculations, single-sphere problem with the slip boundary condition is solved by Lamb's general solution and the expression of multipole expansions, and Fax\'{e}n's laws of force, torque, and stresslet for slip particle are also derived. Read More

Affiliations: 1National Nuclear Research University, MEPhI, Russia, 2National Nuclear Research University, MEPhI, Russia, 3National Research Centre Kurchatov Institute, Russia, 4National Nuclear Research University, MEPhI, Russia, 5National Nuclear Research University, MEPhI, Russia, 6National Nuclear Research University, MEPhI, Russia, 7National Nuclear Research University, MEPhI, Russia, 8National Nuclear Research University, MEPhI, Russia, 9Petersburg Nuclear Physics Institute, Russia, 10National Nuclear Research University, MEPhI, Russia, 11SSC RF Institute for Theoretical and Experimental Physics, Russia, 12National Nuclear Research University, MEPhI, Russia, 13National Nuclear Research University, MEPhI, Russia, 14National Nuclear Research University, MEPhI, Russia, 15National Nuclear Research University, MEPhI, Russia, 16National Nuclear Research University, MEPhI, Russia, 17National Nuclear Research University, MEPhI, Russia, 18National Nuclear Research University, MEPhI, Russia, 19National Nuclear Research University, MEPhI, Russia, 20National Nuclear Research University, MEPhI, Russia, 21National Nuclear Research University, MEPhI, Russia, 22National Nuclear Research University, MEPhI, Russia, 23National Nuclear Research University, MEPhI, Russia, 24National Nuclear Research University, MEPhI, Russia, 25National Nuclear Research University, MEPhI, Russia, 26National Nuclear Research University, MEPhI, Russia, 27National Research Centre Kurchatov Institute, Russia, 28National Nuclear Research University, MEPhI, Russia, 29National Nuclear Research University, MEPhI, Russia, 30National Nuclear Research University, MEPhI, Russia, 31National Research Centre Kurchatov Institute, Russia, 32National Nuclear Research University, MEPhI, Russia, 33National Research Centre Kurchatov Institute, Russia, 34National Research Centre Kurchatov Institute, Russia, 35National Nuclear Research University, MEPhI, Russia, 36National Nuclear Research University, MEPhI, Russia, 37National Nuclear Research University, MEPhI, Russia, 38National Nuclear Research University, MEPhI, Russia, 39National Nuclear Research University, MEPhI, Russia, 40National Nuclear Research University, MEPhI, Russia, 41National Nuclear Research University, MEPhI, Russia, 42National Research Centre Kurchatov Institute, Russia, 43National Research Centre Kurchatov Institute, Russia, 44National Nuclear Research University, MEPhI, Russia, 45SSC RF Institute for Theoretical and Experimental Physics, Russia

We propose to detect and to study neutrino neutral current coherent scattering off atomic nuclei with a two-phase emission detector using liquid xenon as a working medium. Expected signals and backgrounds are calculated for two possible experimental sites: Kalinin Nuclear Power Plant in the Russian Federation and Spallation Neutron Source at the Oak Ridge National Laboratory in the USA. Both sites have advantages as well as limitations. Read More

We studied the application of statistical reconstruction algorithms, namely maximum likelihood and least squares methods, to the problem of event reconstruction in a dual phase liquid xenon detector. An iterative method was developed for in-situ reconstruction of the PMT light response functions from calibration data taken with an uncollimated gamma-ray source. Using the techniques described, the performance of the ZEPLIN-III dark matter detector was studied for 122 keV gamma-rays. Read More

ZEPLIN-III is a two-phase xenon direct dark matter experiment located at the Boulby Mine (UK). After its first science run in 2008 it was upgraded with: an array of low background photomultipliers, a new anti-coincidence detector system with plastic scintillator and an improved calibration system. After 319 days of data taking the second science run ended in May 2011. Read More

Plastic scintillators are widely used in industry, medicine and scientific research, including nuclear and particle physics. Although one of their most common applications is in neutron detection, experimental data on their response to low-energy nuclear recoils are scarce. Here, the relative scintillation efficiency for neutron-induced nuclear recoils in a polystyrene-based plastic scintillator (UPS-923A) is presented, exploring recoil energies between 125 keV and 850 keV. Read More

We present an experimental study of single electron emission in ZEPLIN-III, a two-phase xenon experiment built to search for dark matter WIMPs, and discuss applications enabled by the excellent signal-to-noise ratio achieved in detecting this signature. Firstly, we demonstrate a practical method for precise measurement of the free electron lifetime in liquid xenon during normal operation of these detectors. Then, using a realistic detector response model and backgrounds, we assess the feasibility of deploying such an instrument for measuring coherent neutrino-nucleus elastic scattering using the ionisation channel in the few-electron regime. Read More

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. Read More

ZE3RA is the software package responsible for processing the raw data from the ZEPLIN-III dark matter experiment and its reduction into a set of parameters used in all subsequent analyses. The detector is a liquid xenon time projection chamber with scintillation and electroluminescence signals read out by an array of 31 photomultipliers. The dual range 62-channel data stream is optimised for the detection of scintillation pulses down to a single photoelectron and of ionisation signals as small as those produced by single electrons. Read More

Scintillation and ionisation yields for nuclear recoils in liquid xenon above 10 keVnr (nuclear recoil energy) are deduced from data acquired using broadband Am-Be neutron sources. The nuclear recoil data from several exposures to two sources were compared to detailed simulations. Energy-dependent scintillation and ionisation yields giving acceptable fits to the data were derived. Read More

The ZEPLIN-III experiment is operating in its second phase at the Boulby Underground Laboratory in search of dark matter WIMPs. The major upgrades to the instrument over its first science run include lower background photomultiplier tubes and installation of a plastic scintillator veto system. Performance results from the veto detector using calibration and science data in its first six months of operation in coincidence with ZEPLIN-III are presented. Read More

Hydrogenation has proven to be an effective tool to open the bandgap of graphene. In the present density functional study we demonstrate that single-side-hydrogenated graphene is a semiconductor with an indirect bandgap of 1.89 eV, in between the gapless graphene and wide bandgap graphane. Read More

The design, optimisation and construction of an anti-coincidence veto detector to complement the ZEPLIN-III direct dark matter search instrument is described. One tonne of plastic scintillator is arranged into 52 bars individually read out by photomultipliers and coupled to a gadolinium-loaded passive polypropylene shield. Particular attention has been paid to radiological content. Read More

We have investigated the interactions of 1 A GeV 56Fe in nuclear emulsion. We measured the charge and the angular distributions of single and multiple charged relativistic particles emitted from peripheral interactions. We investigate a possible new method of separating interactions of electromagnetic origin. Read More

The technique of nuclear track emulsions is used to explore the fragmentation of light relativistic nuclei down to the most peripheral interactions - nuclear "white" stars. A complete pattern of therelativistic dissociation of a $^8$B nucleus with target fragment accompaniment is presented. Relativistic dissociation $^{9}$Be$\to2\alpha$ is explored using significant statistics and a relative contribution of $^{8}$Be decays from 0$^+$ and 2$^+$ states is established. Read More

Affiliations: 1Dubna, JINR, 2Dubna, JINR, 3Dubna, JINR, 4Dubna, JINR, 5Dubna, JINR, 6Dubna, JINR, 7Dubna, JINR, 8Dubna, JINR, 9Dubna, JINR, 10Dubna, JINR, 11Dubna, JINR, 12Dubna, JINR, 13Kosice U., 14Lebedev Inst., 15Lebedev Inst., 16Lebedev Inst., 17Lebedev Inst., 18Lebedev Inst., 19Lebedev Inst., 20Bucharest, Inst. Space Sciences

Experimental data on fragmentation channels in peripheral interactions of $^8$B nuclei in nuclear track emulsions are presented. A detailed analysis made it possible to justify selections of events of the electromagnetic-dissociation process $^8$B $\to^7$Be + \emph{p} and to estimate its cross section. Events of $^{10}$C peripheral dissociation that were observed in the same exposure are described. Read More

EXO-200 uses 468 large area avalanche photodiodes (LAAPDs) for detection of scintillation light in an ultra-low-background liquid xenon (LXe) detector. We describe initial measurements of dark noise, gain and response to xenon scintillation light of LAAPDs at temperatures from room temperature to 169K - the temperature of liquid xenon. We also describe the individual characterization of more than 800 LAAPDs for selective installation in the EXO-200 detector. Read More

A method is described that allows calibration and assessment of the linearity of response of an array of photomultiplier tubes. The method does not require knowledge of the photomultiplier single photoelectron response model and uses science data directly, thus eliminating the need for dedicated data sets. In this manner all photomultiplier working conditions (e. Read More

We present new experimental constraints on the WIMP-nucleon spin-dependent elastic cross-sections using data from the first science run of ZEPLIN-III, a two-phase xenon experiment searching for galactic dark matter WIMPs based at the Boulby mine. Analysis of $\sim$450 kg$\cdot$days fiducial exposure revealed a most likely signal of zero events, leading to a 90%-confidence upper limit on the pure WIMP-neutron cross-section of $\sigma_n=1.8\times 10^{-2}$ pb at 55 GeV/$c^2$ WIMP mass. Read More

The ZEPLIN-III experiment in the Palmer Underground Laboratory at Boulby uses a 12kg two-phase xenon time projection chamber to search for the weakly interacting massive particles (WIMPs) that may account for the dark matter of our Galaxy. The detector measures both scintillation and ionisation produced by radiation interacting in the liquid to differentiate between the nuclear recoils expected from WIMPs and the electron recoil background signals down to ~10keV nuclear recoil energy. An analysis of 847kg. Read More

The physical spin program at high $p_T$ region and energies $s^{1/2}_{NN} \sim 10 GeV$ is discussed. It's shown that cumulative processes, color transparency problem and polarization phenomenons directly connect with properties new form of the nuclear matter as Color Quark Condensate(CQC). Studies of CQC one of the most important physical problem and can be realized using polarized ion beams at JINR nuclotron-M (and in future at NICA). Read More

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. Read More

Experimental results on peripheral fragmentation of relativistic $^{11}$B nuclei are presented. In the experiment the emulsions exposured to $^{11}$B beam with momentum 2.75 A GeV/c at the JINR Nuclotron are used. Read More

We study the properties of configurations from which P-vortices on one hand or Abelian monopoles on the other hand have been removed. We confirm the loss of confinement in both cases and investigate in what respect the modified ensembles differ from the confining ones from the point of view of the complementary confinement scenario. Read More

We study the spectrum of low-lying eigenmodes of the kinetic operator for scalar particles, in the color adjoint representation of Yang-Mills theory. The kinetic operator is the covariant Laplacian, plus a constant which serves to renormalize mass. In the pure gauge theory, our data indicates that the interval between the lowest eigenvalue and the mobility edge tends to infinity in the continuum limit. Read More

The results of investigations dealing with the charge topology of the fragments produced in peripheral dissociation of relativistic $^8$B nuclei in emulsion are presented. 55 events of peripheral dissociation of the $^8$B nucleus were selected from the events which do not involve the production of the target-nucleus fragments and mesons (`` white\rq\rq ~stars). A leading contribution of the $^8$B$\to^7$Be+p mode having the lowest energy threshold was revealed on the basis of those events. Read More

We present details of the technical design and manufacture of the ZEPLIN-III dark matter experiment. ZEPLIN-III is a two-phase xenon detector which measures both the scintillation light and the ionisation charge generated in the liquid by interacting particles and radiation. The instrument design is driven by both the physics requirements and by the technology requirements surrounding the use of liquid xenon. Read More

The results of investigations of the dissociation of a $^{14}$N nucleus of momentum 2.86~A~GeV/c in photo-emulsion are presented. The main characteristics of these reactions, that is the cross sections for various fragmentation channels, are given. Read More

Nuclei of $^7$Li were accelerated at the JINR Nuclotron. After the charge-exchange reaction involving these nuclei at an external target a second $^7$Be beam of energy 1.23A GeV was formed. Read More

The results of investigations of the relativistic $^9$Be nucleus fragmentation in emulsion which entails the production of two He fragments of an energy of 1.2~A~GeV are presented. The results of the angular measurements of the $^9$Be$\to$2He events are analyzed. Read More

In the present paper, experimental observations of the multifragmentation processes of light relativistic nuclei carried out by means of emulsions are reviewed. Events of the type of "white" stars in which the dissociation of relativistic nuclei is not accompanied by the production of mesons and the target-nucleus fragments are considered. A distinctive feature of the charge topology in the dissociation of the Ne, Mg, Si, and S nuclei is an almost total suppression of the binary splitting of nuclei to fragments with charges higher than 2. Read More

We give an overview of results and prospects of nuclear clustering studies on the grounds of the observations of interactions of light stable and radioactive nuclei with an initial energy above 1 A GeV in nuclear emulsions. Thank to the best spatial resolution and the full solid angle acceptance provided by nuclear emulsions, such an approach allows one to obtain unique and evident observations reecting cluster-like features in light nuclear structures. New results on dissociation of $^7$Be in very peripheral interactions with emulsion nuclei are presented. Read More

We present results from a GEANT4-based Monte Carlo tool for end-to-end simulations of the ZEPLIN-III dark matter experiment. ZEPLIN-III is a two-phase detector which measures both the scintillation light and the ionisation charge generated in liquid xenon by interacting particles and radiation. The software models the instrument response to radioactive backgrounds and calibration sources, including the generation, ray-tracing and detection of the primary and secondary scintillations in liquid and gaseous xenon, and subsequent processing by data acquisition electronics. Read More

Affiliations: 1Moscow, ITEP, 2Moscow, ITEP, 3Moscow, ITEP, 4Munich, Max Planck Inst.

We study correlations between low-lying modes of the overlap Dirac operator and vacuum defects, center vortices and three-dimensional volumes, in lattice SU(2) gluodynamics. The low-lying modes are apparently sensitive to topological properties of the underlying gluon field configurations while the vacuum defects are crucial for the confinement. We find distinct positive correlation in both cases. Read More

We review briefly recent results of lattice simulations on 3d domains in the vacuum state of SU(2) gluodynamics. The defects are defined as unification of all the negative links in central projection under condition that the total number of negative links is minimized. In the continuum limit, negative links correspond, generally speaking to singular fields. Read More

Performing lattice simulations of the four dimensional SU(2)gluodynamics we find evidence for existence of three-dimensional domains whose total volume scales in physical units. Technically, the domains are defined in terms of the minimal density of negative links in Z(2) projection of gauge fields. The volume can be viewed also as the minimal volume bound by the center vortices. Read More