Laboratory for Experimental Nuclear Physics
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National Research Nuclear University, "MEPhI"
Laboratory for Experimental Nuclear Physics

Publications in top-rated journals

1. Title: Direct Measurement of Backgrounds using Reactor-Off Data in Double Chooz
Authors: Y.Abe et al.
Annotations: Double Chooz is unique among modern reactor-based neutrino experiments studying ν̅ e disappearance in that data can be collected with all reactors off. In this paper, we present data from 7.53 days of reactor-off running. Applying the same selection criteria as used in the Double Chooz reactor-on oscillation analysis, a measured background rate of 1.0±0.4 events/day is obtained. The background model for accidentals, cosmogenic β-n-emitting isotopes, fast neutrons from cosmic muons, and stopped-μ decays used in the oscillation analysis is demonstrated to be correct within the uncertainties. Kinematic distributions of the events, which are dominantly cosmic-ray-produced correlated-background events, are provided. The background rates are scaled to the shielding depths of two other reactor-based oscillation experiments, Daya Bay and RENO.
Published in: Phys.Rev.D 87(2013)011102

2. Title: First Measurement of theta-13 from Delayed Neutron Capture on Hydrogen in the Double Chooz Experiment
Authors: Y.Abe et al.
Annotations: The Double Chooz experiment has determined the value of the neutrino oscillation parameter theta(13) from an analysis of inverse beta decay interactions with neutron capture on hydrogen. This analysis uses a three times larger fiducial volume than the standard Double Chooz assessment, which is restricted to a region doped with gadolinium (Gd), yielding an exposure of 113.1 GW-ton-years. The data sample used in this analysis is distinct from that of the Gd analysis, and the systematic uncertainties are also largely independent, with some exceptions, such as the reactor neutrino flux prediction. A combined rate- and energy-dependent fit finds sin(2) 2 theta(13) = 0.097 +/- 0.034 (stat.) +/- 0.034 (syst.), excluding the no-oscillation hypothesis at 2.0 sigma. This result is consistent with previous measurements of sin(2) 2 theta(13).
Published in: Phys.Lett.B 723(2013)66-70

3. Title: Deployment of a Two-phase Emission Liquid Xenon Detector for Study of Low-Ionization Events at the Research Reactor IRT MEPhI
Authors: D.Akimov et al.
Annotations: A two-phase emission detector containing 5 kg of liquid xenon is installed at the horizontal experimental channel of the research nuclear reactor in order to investigate a possibility to detect Xenon atom recoils with kinetic energy below 1 keV. Preliminary tests have demonstrated that the detector is capable of detecting and identifying single electron events. It is shown that this kind of the detector technology can be used for observation of reactor antineutrino coherent elastic scattering off Xenon nuclei.
Published in: IEEE Trans.Nucl.Sci.

4. Title: Prospects for observation of neutrino-nuclear neutral current coherent scattering with two-phase Xenon emission detector
Authors: D.Akimov et al.
Annotations: 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: the Kalinin Nuclear Power Plant in the Russian Federation and the Spallation Neutron Source at the Oak Ridge National Laboratory in the U.S.A. Both sites have advantages as well as limitations. The experiment looks feasible at either location.
Published in: JINST – 2013.

5. Title: The LUX prototype detector: Heat exchanger development
Authors: D. Akerib e.a.
Annotations: The LUX (large underground xenon) detector is a two-phase xenon time projection chamber (TPC) designed to search for WIMP–nucleon dark matter interactions. As with all noble element detectors, continuous purification of the detector medium is essential to produce a large (>1ms) electron lifetime; this is necessary for efficient measurement of the electron signal which in turn is essential for achieving robust discrimination of signal from background events. In this paper, we describe the development of a novel purification system deployed in a prototype detector. The results from the operation of this prototype indicated heat exchange with an efficiency above 94% up to a flow rate of 42 slpm, allowing for an electron drift length greater than 1 m to be achieved in approximately 2 days and sustained for the duration of the testing period.
Published in: NIM A 709(2013)29-36

6. Title: The Large Underground Xenon (LUX) experiment
Authors: D.Akerib e.a.
Annotations: The Large Underground Xenon (LUX) collaboration has designed and constructed a dual-phase xenon detector, in order to conduct a search for Weakly Interacting Massive Particles(WIMPs), a leading dark matter candidate. The goal of the LUX detector is to clearly detect (or exclude) WIMPS with a spin independent cross section per nucleon of 2×10 −46 cm 2 , equivalent to ∼ 1 event/100 kg/month in the inner 100-kg fiducial volume (FV) of the 370- kg detector. The overall background goals are set to have < 1 background events characterized as possible WIMPs in the FV in 300 days of running. This paper describes the design and construction of the LUX detector.
Published in: NIM A 704(2013)111-126

7. Title: Reactor electron antineutrino disappearance in the Double Chooz experiment
Authors: Y.Abe et al.
Annotations: The Double Chooz experiment has observed 8,249 candidate electron antineutrino events in 227.93 live days with 33.71 GW-ton-years (reactor power x detector mass x livetime) exposure using a 10.3 cubic meter fiducial volume detector located at 1050 m from the reactor cores of the Chooz nuclear power plant in France. The expectation in case of theta13 = 0 is 8,937 events. The deficit is interpreted as evidence of electron antineutrino disappearance. From a rate plus spectral shape analysis we find sin^2 2{\theta}13 = 0.109 \pm 0.030(stat) \pm 0.025(syst). The data exclude the no-oscillation hypothesis at 99.8% CL (2.9{\sigma}).
Published in: Phys.Rev.D 86(2012)052008

8. Title: First Test of Lorentz Violation with a Reactor-based Antineutrino Experiment
Authors: Y.Abe et al.
Annotations: We present a search for Lorentz violation with 8249 candidate electron antineutrino events taken by the Double Chooz experiment in 227.9 live days of running. This analysis, featuring a search for a sidereal time dependence of the events, is the first test of Lorentz invariance using a reactor-based antineutrino source. No sidereal variation is present in the data and the disappearance results are consistent with sidereal time independent oscillations. Under the Standard-Model Extension, we set the first limits on 14 Lorentz violating coefficients associated with transitions between electron and tau flavor, and set two competitive limits associated with transitions between electron and muon flavor.
Published in: Phys.Rev. D 86(2012)112009

9. Title: Аппаратурный комплекс по измерению отклика жидкого ксенона для ядер отдачи низких энергий на реакторе ИРТ МИФИ
Authors: Д.Ю.Акимов и др.
Annotations: Для проведения эксперимент по наблюдению редкого процесса когерентного рассеяния реакторных антинейтрино на тяжелых атомных ядрах, когда должны регистрироваться ядра отдачи с энергиями на уровне сотен эВ, и экспериментов по поиску Темной материи с помощью детекторов на сжиженных благородных газах, необходимо исследовать ионизп\ационный выход и сцинтилляционную эффективность жидкого ксенона для ядер отдачи в области низких энергий. Измерения планируется проводить с помощью двухфазного эмиссионного детектора с массой рабочего вещества в чувствительном объеме 0,6 кг. Детектор установлен на пучке квазимонохроматических нейтронов, который формируется с помощью интерференционных фильтров, установленных в экспериментальном канале ГЭК-10 исследовательского реактора ИРТ МИФИ. В работе приводится описание детектора и методики измерений, сделана оценка достижимой точности измерений.
Published in: Ядерная физика и инжиниринг 3(2012)490-495

10. Title: Indication for the disappearance of reactor electron antineutrinos in the Double Chooz experiment
Authors: Y.Abe et al.
Annotations: The Double Chooz Experiment presents an indication of reactor electron antineutrino disappearance consistent with neutrino oscillations. A ratio of 0.944 ± 0.016 (stat) ± 0.040 (syst) observed to predicted events was obtained in 101 days of running at the Chooz Nuclear Power Plant in France, with two 4.25 GW th reactors. The results were obtained from a single 10 m 3 fiducial volume detector located 1050 m from the two reactor cores. The reactor antineutrino flux prediction used the Bugey4 measurement as an anchor point. The deficit can be interpreted as an indication of a non-zero value of the still unmeasured neutrino mixing parameter \sang. Analyzing both the rate of the prompt positrons and their energy spectrum we find \sang = 0.086 ± 0.041 (stat) ± 0.030 (syst), or, at 90% CL, 0.015 < \sang < 0.16.
Published in: Phys.Rev.Lett. 108(2012)131801

11. Title: Измерение одноэлектронных шумов в эмиссионном детекторе на жидком ксеноне
Authors: Д.Ю.Акимов и др.
Annotations: A technique for studying single electron noise in emission detectors that are intended for detection of rare processes with small energy releases is developed. Examples of possible applications are experiments for search of dark matter in the Universe and detection of reactor antineutrinos via coherent neutrino scattering at heavy xenon nuclei. We present the first results of studying the nature of single electron noise in a liquid xenon emission detector and consider possible ways to suppress it.
Published in: Приборы и техника эксперимента. - 2012. - N 4. - С. 7-13

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