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Search Results: 1 - 10 of 418366 matches for " S. V. Pereverzev "
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Energy-resolved detection of single infrared photons with λ = 8 μm using a superconducting microbolometer
Boris S. Karasik,Sergey V. Pereverzev,Alexander Soibel,Daniel F. Santavicca,Daniel E. Prober,David Olaya,Michael E. Gershenson
Physics , 2012, DOI: 10.1063/1.4739839
Abstract: We report on the detection of single photons with {\lambda} = 8 {\mu}m using a superconducting hot-electron microbolometer. The sensing element is a titanium transition-edge sensor with a volume ~ 0.1 {\mu}m^3 fabricated on a silicon substrate. Poisson photon counting statistics including simultaneous detection of 3 photons was observed. The width of the photon-number peaks was 0.11 eV, 70% of the photon energy, at 50-100 mK. This achieved energy resolution is one of the best figures reported so far for superconducting devices. Such devices can be suitable for single photon calorimetric spectroscopy throughout the mid-infrared and even the far-infrared.
First measurement of the ionization yield of nuclear recoils in liquid argon
T. H. Joshi,S. Sangiorgio,A. Bernstein,M. Foxe,C. Hagmann,I. Jovanovic,K. Kazkaz,V. Mozin,E. B. Norman,S. V. Pereverzev,F. Rebassoo,P. Sorensen
Physics , 2014, DOI: 10.1103/PhysRevLett.112.171303
Abstract: This Letter details a measurement of the ionization yield ($Q_y$) of 6.7 keV $^{40}Ar$ atoms stopping in a liquid argon detector. The $Q_y$ of 3.6-6.3 detected $e^{-}/\mbox{keV}$, for applied electric fields in the range 240--2130 V/cm, is encouraging for the use of this detector medium to search for the signals from hypothetical dark matter particle interactions and from coherent elastic neutrino nucleus scattering. A significant dependence of $Q_y$ on the applied electric field is observed and explained in the context of ion recombination.
Energy resolution of terahertz single-photon-sensitive bolometric detectors
D. F. Santavicca,B. Reulet,B. S. Karasik,S. V. Pereverzev,D. Olaya,M. E. Gershenson,L. Frunzio,D. E. Prober
Physics , 2009, DOI: 10.1063/1.3336008
Abstract: We report measurements of the energy resolution of ultra-sensitive superconducting bolometric detectors. The device is a superconducting titanium nanobridge with niobium contacts. A fast microwave pulse is used to simulate a single higher-frequency photon, where the absorbed energy of the pulse is equal to the photon energy. This technique allows precise calibration of the input coupling and avoids problems with unwanted background photons. Present devices have an intrinsic full-width at half-maximum energy resolution of approximately 23 terahertz, near the predicted value due to intrinsic thermal fluctuation noise.
First demonstration of a sub-keV electron recoil energy threshold in a liquid argon ionization chamber
S. Sangiorgio,T. H. Joshi,A. Bernstein,J. Coleman,M. Foxe,C. Hagmann,I. Jovanovic,K. Kazkaz,K. Mavrokoridis,V. Mozin,S. Pereverzev,P. Sorensen
Physics , 2013, DOI: 10.1016/j.nima.2013.06.061
Abstract: We describe the first demonstration of a sub-keV electron recoil energy threshold in a dual-phase liquid argon time projection chamber. This is an important step in an effort to develop a detector capable of identifying the ionization signal resulting from nuclear recoils with energies of order a few keV and below. We obtained this result by observing the peaks in the energy spectrum at 2.82 keV and 0.27 keV, following the K- and L-shell electron capture decay of Ar-37, respectively. The Ar-37 source preparation is described in detail, since it enables calibration that may also prove useful in dark matter direct detection experiments. An internally placed Fe-55 x-ray source simultaneously provided another calibration point at 5.9 keV. We discuss the ionization yield and electron recombination in liquid argon at those three calibration energies.
Evolution of technogenic landscapes by the example of apatite-nepheline ore concentration wastes  [PDF]
Vladimir N. Pereverzev, Galina A. Evdokimova, Irina V. Zenkova, Maria V. Korneykova, Vera V. Redkina
Natural Science (NS) , 2010, DOI: 10.4236/ns.2010.26075
Abstract: A primary soil-forming process can take place on the concentration waste of apatite-nepheline ores, whose biological recultivation was carried out more than 40 years ago. This process is characterized by the following features: forming of a thin litter with the content of organic carbon at the level of 8-12%, accumulation of humic substances in the sub-litter layer and the change of рН values. Microorganisms are biocatalysts of primary soil formation processes and one of the main factors that determine the specificity of this process. The prokaryotic complex of the newly formed soils, generated from nepheline sands, is considerably different from that of zonal soils on moraine sediments. The former ones are dominated by gram-positive bacteria, mainly actinobacteria, as well as by their filamentous forms (actinomycetes), whereas the latter ones are dominated by gram-negative bacteria. A common feature of invertebrate’s complexes in nepheline sands is the low species diversity, small-size and quickly development of microfauna and mesofauna representatives and the dependence of succession of microarthropods pioneer groups on the succession of bacteria and fungi.
Discretized Tikhonov regularization for Robin boundaries localization
Hui Cao,Sergei V. Pereverzev,Eva Sincich
Mathematics , 2013,
Abstract: We deal with a boundary detection problem arising in nondestructive testing of materials. The problem consists in recovering an unknown portion of the boundary, where a Robin condition is satisfied, with the use of a Cauchy data pair collected on the accessible part of the boundary. We combine a linearization argument with a Tikhonov regularization approach for the local reconstruction of the unknown defect. Moreover, we discuss the regularization parameter choice by means of the so called balancing principle and we present some numerical tests that show the efficiency of our method.
Microwave-Induced Dephasing in One-Dimensional Metal Wires
J. Wei,S. Pereverzev,M. E. Gershenson
Physics , 2005, DOI: 10.1103/PhysRevLett.96.086801
Abstract: We report on the effect of monochromatic microwave (MW) radiation on the weak localization corrections to the conductivity of quasi-one-dimensional (1D) silver wires. Due to the improved electron cooling in the wires, the MW-induced dephasing was observed without a concomitant overheating of electrons over wide ranges of the MW power $P_{MW}$ and frequency $f$. The observed dependences of the conductivity and MW-induced dephasing rate on $P_{MW}$ and $f$ are in agreement with the theory by Altshuler, Aronov, and Khmelnitsky \cite{Alt81}. Our results suggest that in the low-temperature experiments with 1D wires, saturation of the temperature dependence of the dephasing time can be caused by an MW electromagnetic noise with a sub-pW power.
A New Model of Chemical Bonding in Ionic Melts
Vitaly V. Chaban,Yuriy V. Pereverzev,Oleg V. Prezhdo
Physics , 2012, DOI: 10.1063/1.4705668
Abstract: We developed a new physical model to predict macroscopic properties of inorganic molten systems using a realistic description of inter-atomic interactions. Unlike the conventional approach, which tends to overestimate viscosity by several times, our systems consist of a set of ions with an admixture of neutral atoms. The neutral atom subsystem is a consequence of the covalent/ionic state reduction, occurring in the liquid phase. Comparison of the calculated macroscopic properties (shear viscosity and self-diffusion constants) with the experiment demonstrates good performance of our model. The presented approach is inspired by a significant degree of covalent interaction between the alkali and chlorine atoms, predicted by the coupled cluster theory.
A novel psychophysiological model of the effect of alcohol use on academic performance of male medical students of Belarusian State Medical University
Menizibeya O. Welcome,Elena V. Pereverzeva,Vladimir A. Pereverzev
International Journal of Collaborative Research on Internal Medicine & Public Health , 2010,
Abstract: Background: The blood glucose concentration might determine the degree of academic performance. Decrease in the glucose concentration leads to a lowering of cognitive functions. Objectives: To produce a model of students’ alcohol use based on glucose homeostasis control and cognitive functions. Methods: The study involved 13 male volunteers (8 moderate alcohol users and 5 non-alcohol users) – medical students and took 6.5 hours on fasting. Selection criteria were based on a screening survey conducted among students in Minsk, Belarus. Out of 1499 students, 185 were abstainers, 1052 – moderate drinkers, 262 – problem drinkers. The experiment was divided into three phases: first phase – the students were administered AUDIT, MAST, CAGE, STAI, Academic Performance questionnaires; second phase - the students worked with text № 1 (physiology of bone tissue and subsequently answered on the questions that followed it); third phase – with text № 2 (physiology of autonomic nervous system and also answered subsequently on the questions that followed it). Blood glucose level was measured at 2 hours intervals, including the initial level. Tests on short-term, long-term memory and attention were used in every phase of the experiment. The probability value for significance was set at p<0.05. Results: The moderate drinkers had significantly lower glucose concentration after 4-6 hours, compared to their initial concentration, as well as to the values of the abstainers. Disturbances in cognitive functions, precisely a decrease in the effectiveness of active attention and a faster development of fatigue after 4-6 hours of mental work in alcohol users, compared to abstainers was statistically proven. The Intellectual Capacity on various tests/tasks positively correlated with the blood glucose level and in the 2-3 phases of the experiment and according to the results of the academic performances (ρ = +0.75; p<0.01). Alcohol users had 12.5–40.0 times higher number of errors on various tests/tasks than the non-alcohol users (p<0.001). The errors made on various tests/tasks increased with decrease in the blood glucose concentration (ρ = – 0.83; p<0.01). Significant increase in the Visual Productivity Coefficient among abstainers was also observed (p<0.05). Conclusion: This is the first study to show that alcohol use, even in episodic moderate doses (28ml/person with 1-2 times frequency per month) is accompanied by long-term glucose homeostasis disorders, leading to cognitive function disturbances and a decrease in the effectiveness of mental activities. These disorders in gluco
Constraints on the two-particle distribution function due to the permutational symmetry of the higher order distribution functions
Andrey Pereverzev
Physics , 2005, DOI: 10.1103/PhysRevB.73.174411
Abstract: We investigate how the range of parameters that specify the two-particle distribution function is restricted if we require that this function be obtained from the $n^{\rm th}$ order distribution functions that are symmetric with respect to the permutation of any two particles. We consider the simple case when each variable in the distribution functions can take only two values. Results for all $n$ values are given, including the limit of $n\to\infty$. We use our results to obtain bounds on the allowed values of magnetization and magnetic susceptibility in an $n$ particle Fermi fluid.
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