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Search Results: 1 - 10 of 461843 matches for " A. Lubashevskiy "
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Hydrogen induced nonmonotonic relaxation in binary mixtures similar to Pd-Er alloys as a transition process in nonequilibrium heterogeneous systems with spinodal decomposition
A. A. Katsnelson,I. A. Lubashevskiy,A. Yu. Lavrenov
Physics , 2000,
Abstract: We have proposed a qualitative model for the structure of binary systems similar to Pd-Er alloys, which explains their nonmonotonic relaxation after the hydrogen saturation. It is based on the assumption that such a solid solution involves two kind heterogeneities. The former are caused by spinodal decomposition of the initially homogeneous state of the solid solution into the phases enriched and depleted of Er atoms. The latter are crystalline defects that trap an additional amount of Er atoms, which leads also to their local accumulation, changing the defect properties. Hydrogen atoms penetrating into the solid disturb the equilibrium of both the phase separation and the defect saturation with Er atoms, causing redistribution of Er atoms. The diffusion fluxes give rise to the motion of the interface between the two phases that is responsible for time variations, for example, in the relative volume of the enriched phase observed experimentally. We have found the conditions when the interface motion can change the direction during the system relaxation to a new equilibrium state. The latter effect is, from our point of view, the essence of the hydrogen induced nonmonotonic relaxation observed in such systems. The numerical simulation confirms the basic assumptions.
Algorithm for Resource Redistribution Required for Recovery of Society after Large Scale Disasters
Vasily Lubashevskiy,Taro Kanno,Kazuo Furuta
Physics , 2013,
Abstract: The recovery of society after a large scale disaster generally consists of two phases, short- and long-term recoveries. The problem of short-term recovery is rather close to the problem of resilience in their goal, namely, bouncing the damaged system back to the operating standards. The present paper proposes an algorithm for the vital resource redistribution required for implementation of the short-term recovery. The developed model is based on the cooperative interaction of cities during the resource redistribution, ordering the cities according to their priority in resource delivery, and a generating a semi-optimal plan for the desired redistribution. Nonlinear effects caused by the city limit capacities are taken into account. Two types of systems, "uniform" and "centralized", are studied numerically. In particular it is demonstrated that the cooperation effects are able to shorten substantially the duration of the process required for its implementation.
Resource Redistribution under Lack of Information: Short-Term Recovery after Large Scale Disasters
Vasily Lubashevskiy,Taro Kanno,Kazuo Furuta
Physics , 2013,
Abstract: The paper is devoted to the problem of disaster mitigation. It develops an emergent mechanism of resource redistribution aimed at recovering of a socio-technological system affected by a large scale disaster. The basic requirements to the short-term recovery are taken into account in constructing this mechanism. The system at hand consists of many individual units (cities) and the mechanism is based on their cooperative interaction, which makes the resource redistribution efficient regardless of the particular position of affected region. Previously we studied the dynamics of supply process governed by this mechanism when all the information about the system is available and actual from the beginning of the process (V. Lubashevskiy, T. Kanno, K. Furuta, arXiv:1310.0648). In the present paper we analyze the effects of lack of information on the resource delivery rate. Two scenarios of the lack of information are allowed for. The first one is the delay of the information about the city states. The second one is its incompleteness. As a result of simulation, it is demonstrated that the duration of the resource redistribution governed by the developed mechanism is weakly affected by the lack of information.
Resource Redistribution Method for Short-Term Recovery of Society after Large Scale Disasters
Vasily Lubashevskiy,Taro Kanno,Kazuo Furuta
Physics , 2014,
Abstract: Recovery of society after a large scale disaster generally consists of two phases, short- and long-term recoveries. The main goal of the short-term recovery is to bounce the damaged system back to the operating standards enabling residents in damaged cities to survive, and fast supply with vital resources to them is one of its important elements. We propose a general principle by which the required redistribution of vital resources between the affected and neighbouring cities can be efficiently implemented. The short-term recovery is a rescuer operation where uncertainty in evaluating the state of damaged region is highly probable. To allow for such an operation the developed principle involves two basic components. The first one of ethic nature is the triage concept determining the current city priority in the resource delivery. The second one is the minimization of the delivery time subjected to this priority. Finally a certain plan of the resource redistribution is generated according to this principle. Several specific examples are studied numerically. It elucidates, in particular, the effects of system characteristics such as the city limit capacity in resource delivery, the type of initial resource allocation among the cities, the number of cities able to participate in the resource redistribution, and the damage level in the affected cities. As far as the uncertainty in evaluating the state of damaged region is concerned, some specific cases were studied. It assumes the initial communication system has crashed and formation of a new one and the resource redistribution proceed synchronously. The obtained results enable us to consider the resource redistribution plan governed by the proposed method semi-optimal and rather efficient especially under uncertainty.
LArGe - Active background suppression using argon scintillation for the GERDA $0νββ$-experiment
M. Agostini,M. Barnabé-Heider,D. Budjá?,C. Cattadori,A. Gangapshev,K. Gusev,M. Heisel,M. Junker,A. Klimenko,A. Lubashevskiy,K. Pelczar,S. Sch?nert,A. Smolnikov,G. Zuzel
Physics , 2015,
Abstract: LArGe is a GERDA low-background test facility to study novel background suppression methods in a low-background environment, for future application in the GERDA experiment. Similar to GERDA, LArGe operates bare germanium detectors submersed into liquid argon (1 m$^3$, 1.4 tons), which in addition is instrumented with photomultipliers to detect argon scintillation light. The scintillation signals are used in anti-coincidence with the germanium detectors to effectively suppress background events that deposit energy in the liquid argon. The background suppression efficiency was studied in combination with a pulse shape discrimination (PSD) technique using a BEGe detector for various sources, which represent characteristic backgrounds to GERDA. Suppression factors of a few times $10^3$ have been achieved. First background data of LArGe with a coaxial HPGe detector (without PSD) yield a background index of (0.12$-$4.6)$\cdot 10^{-2}$ cts/(keV$\cdot$kg$\cdot$y) (90% C.L.), which is at the level of GERDA Phase I. Furthermore, for the first time we monitor the natural $^{42}$Ar abundance (parallel to GERDA), and have indication for the $2\nu\beta\beta$-decay in natural germanium. These results show the effectivity of an active liquid argon veto in an ultra-low background environment. As a consequence, the implementation of a liquid argon veto in GERDA Phase II is pursued.
Isotopically modified Ge detectors for {\sc Gerda}: from production to operation
D. Budjá?,M. Agostini,L. Baudis,E. Bellotti,L. Bezrukov,R. Brugnera,C. Cattadori,A. di Vacri,R. Falkenstein,A. Garfagnini,S. Georgi,P. Grabmayr,A. Hegai,S. Hemmer,M. Hult,J. Janicskó Csáthy,V. Kornoukhov,B. Lehnert,A. Lubashevskiy,S. Nisi,G. Pivato,S. Sch?nert,M. Tarka,K. von Sturm
Physics , 2013, DOI: 10.1088/1748-0221/8/04/P04018
Abstract: The \textsc{Gerda} experiment searches for the neutrinoless double beta ($0\nu\beta$beta$) decay of $^{76}$Ge using high-purity germanium detectors made of material enriched in $^{76}$Ge. For Phase II of the experiment a sensitivity for the half life $T_{1/2}^{0\nu}\,\,\sim2\cdot10^{26}$ yr is envisioned. Modified Broad Energy Germanium detectors (BEGe) with thick n$^+$ electrodes provide the capability to efficiently identify and reject background events, while keeping a large acceptance for the $0\nu\beta$beta$-decay signal through novel pulse-shape discrimination (PSD) techniques. The viability of producing thick-window BEGe-type detectors for the \textsc{Gerda} experiment is demonstrated by testing all the production steps from the procurement of isotopically modified germanium up to working BEGe detectors. Comprehensive testing of the spectroscopic as well as PSD performance of the \textsc{Gerda} Phase II prototype BEGe detectors proved that the properties of these detectors are identical to those produced previously from natural germanium material following the standard production line of the manufacturer. Furthermore, the production of BEGe detectors from a limited amount of isotopically modified germanium served to optimize the production, in order to maximize the overall detector mass yield. The results of this test campaign provided direct input for the subsequent production of the enriched germanium detectors.
HEROICA: an Underground Facility for the Fast Screening of Germanium Detectors
E. Andreotti,A. Garfagnini,W. Maneschg,N. Barros,G. Benato,R. Brugnera,F. Costa,R. Falkenstein,K. K. Guthikonda,A. Hegai,S. Hemmer,M. Hult,K. Jaenner,T. Kihm,B. Lehnert,H. Liao,A. Lubashevskiy,G. Lutter,G. Marissens,L. Modenese,L. Pandola,M. Reissfelder,C. Sada,M. Salathe,C. Schmitt,O. Schulz,B. Schwingenheuer,M. Turcato,C. Ur,K. von Sturm,V. Wagner,J. Westermann
Physics , 2013, DOI: 10.1088/1748-0221/8/06/P06012
Abstract: An infrastructure to characterize germanium detectors has been designed and constructed at the HADES Underground Research Laboratory, located in Mol (Belgium). Thanks to the 223m overburden of clay and sand, the muon flux is lowered by four orders of magnitude. This natural shield minimizes the exposure of radio-pure germanium material to cosmic radiation resulting in a significant suppression of cosmogenic activation in the germanium detectors. The project has been strongly motivated by a special production of germanium detectors for the GERDA experiment. GERDA, currently collecting data at the Laboratori Nazionali del Gran Sasso of INFN, is searching for the neutrinoless double beta decay of 76Ge. In the near future, GERDA will increase its mass and sensitivity by adding new Broad Energy Germanium (BEGe) detectors. The production of the BEGe detectors is done at Canberra in Olen (Belgium), located about 30km from the underground test site. Therefore, HADES is used both for storage of the crystals over night, during diode production, and for the characterization measurements. A full quality control chain has been setup and tested on the first seven prototype detectors delivered by the manufacturer at the beginning of 2012. The screening capabilities demonstrate that the installed setup fulfills a fast and complete set of measurements on the diodes and it can be seen as a general test facility for the fast screening of high purity germanium detectors. The results are of major importance for a future massive production and characterization chain of germanium diodes foreseen for a possible next generation 1-tonne double beta decay experiment with 76Ge.
First results of the EDELWEISS-II WIMP search using Ge cryogenic detectors with interleaved electrodes
E. Armengaud,C. Augier,A. Benoit,L. Berge,O. Besida,J. Blumer,A. Broniatowski,A. Chantelauze,M. Chapellier,G. Chardin,F. Charlieux,S. Collin,X. Defay,M. De Jesus,P. Di Stefano,Y. Dolgorouki,J. Domange,L. Dumoulin,K. Eitel,J. Gascon,G. Gerbier,M. Gros,M. Hannawald,S. Herve,A. Juillard,H. Kluck,V. Kozlov,R. Lemrani,P. Loaiza,A. Lubashevskiy,S. Marnieros,X-F. Navick,E. Olivieri,P. Pari,B. Paul,S. Rozov,V. Sanglard,S. Scorza,S. Semikh,A. S. Torrento-Coello,L. Vagneron,M-A. Verdier,E. Yakushev,the EDELWEISS Collaboration
Physics , 2009, DOI: 10.1016/j.physletb.2010.03.057
Abstract: The EDELWEISS-II collaboration has performed a direct search for WIMP dark matter with an array of ten 400 g heat-and-ionization cryogenic detectors equipped with interleaved electrodes for the rejection of near-surface events. Six months of continuous operation at the Laboratoire Souterrain de Modane have been achieved. The observation of one nuclear recoil candidate above 20 keV in an effective exposure of 144 kgd is interpreted in terms of limits on the cross-section of spin-independent interactions of WIMPs and nucleons. A cross-section of 1.0x10^-7 pb is excluded at 90%CL for a WIMP mass of 80 GeV/c2. This result demonstrates for the first time the very high background rejection capabilities of these simple and robust detectors in an actual WIMP search experiment.
A detection system to measure muon-induced neutrons for direct Dark Matter searches
V. Yu. Kozlov,E. Armengaud,C. Augier,A. Benoit,L. Berge,O. Besida,J. Blumer,A. Broniatowski,V. Brudanin,A. Chantelauze,M. Chapellier,G. Chardin,F. Charlieux,S. Collin,X. Defay,M. De Jesus,P. Di Stefano,Y. Dolgorouki,J. Domange,L. Dumoulin,K. Eitel,J. Gascon,G. Gerbier,M. Gros,M. Hannawald,S. Herve,A. Juillard,H. Kluck,R. Lemrani,P. Loaiza,A. Lubashevskiy,S. Marnieros,X. -F. Navick,E. Olivieri,P. Pari,B. Paul,S. Rozov,V. Sanglard,S. Scorza,S. Semikh,A. S. Torrento-Coello,L. Vagneron,M-A. Verdier,E. Yakushev
Physics , 2010, DOI: 10.1016/j.astropartphys.2010.06.001
Abstract: Muon-induced neutrons constitute a prominent background component in a number of low count rate experiments, namely direct searches for Dark Matter. In this work we describe a neutron detector to measure this background in an underground laboratory, the Laboratoire Souterrain de Modane. The system is based on 1 m3 of Gd-loaded scintillator and it is linked with the muon veto of the EDELWEISS-II experiment for coincident muon detection. The system was installed in autumn 2008 and passed since then a number of commissioning tests proving its full functionality. The data-taking is continuously ongoing and a count rate of the order of 1 muon-induced neutron per day has been achieved.
A new high-background-rejection dark matter Ge cryogenic detector
A. Broniatowski,X. Defay,E. Armengaud,L. Berge,A. Benoit,O. Besida,J. Blumer,A. Chantelauze,M. Chapellier,G. Chardin,F. Charlieux,S. Collin,O. Crauste,M. De Jesus,P. Di Stefano,Y. Dolgorouki,J. Domange,L. Dumoulin,K. Eitel,J. Gascon,G. Gerbier,M. Gros,M. Hannawald,S. Herve,A. Juillard,H. Kluck,V. Kozlov,R. Lemrani,A. Lubashevskiy,C. Marrache,S. Marnieros,X. -F. Navick,C. Nones,E. Olivieri,P. Pari,B. Paul,S. Rozov,V. Sanglard,S. Scorza,S. Semikh,M. -A. Verdier,L. Vagneron,E. Yakushev
Physics , 2009, DOI: 10.1016/j.physletb.2009.10.036
Abstract: A new design of a cryogenic germanium detector for dark matter search is presented, taking advantage of the coplanar grid technique of event localisation for improved background discrimination. Experiments performed with prototype devices in the EDELWEISS II setup at the Modane underground facility demonstrate the remarkably high efficiency of these devices for the rejection of low-energy $\beta$, approaching 10$^5$ . This opens the road to investigate the range beyond 10$^{-8}$ pb in the WIMP-nucleon collision cross-sections, as proposed in the EURECA project of a one-ton cryogenic detector mass.
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