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Y. Kamyshkov

Publications and source records attributed to Y. Kamyshkov.

36 records · Page 2Linked to original sources
arXiv2014

Ortho-positronium observation in the Double Chooz Experiment

The Double Chooz experiment measures the neutrino mixing angle $θ_{13}$ by detecting reactor $\barν_e$ via inverse beta decay. The positron-neutron space and time coincidence allows for a sizable background rejection, nonetheless liquid scintillator detectors would profit from a positron/electron discrimination, if feasible in large detector, to suppress the remaining background. Standard particle identification, based on particle dependent time profile of photon emission in liquid scintillator, can not be used given the identical mass of the two particles. However, the positron annihilation is sometimes delayed by the ortho-positronium (o-Ps) metastable state formation, which induces a pulse shape distortion that could be used for positron identification. In this paper we report on the first observation of positronium formation in a large liquid scintillator detector based on pulse shape analysis of single events. The o-Ps formation fraction and its lifetime were measured, finding the values of 44$\%$ $\pm$ 12$\%$ (sys.) $\pm$ 5$\%$ (stat.) and $3.68$ns $\pm$ 0.17ns (sys.) $\pm$ 0.15ns (stat.) respectively, in agreement with the results obtained with a dedicated positron annihilation lifetime spectroscopy setup.

physics.ins-det↗
arXiv2014

Precision Muon Reconstruction in Double Chooz

We describe a muon track reconstruction algorithm for the reactor anti-neutrino experiment Double Chooz. The Double Chooz detector consists of two optically isolated volumes of liquid scintillator viewed by PMTs, and an Outer Veto above these made of crossed scintillator strips. Muons are reconstructed by their Outer Veto hit positions along with timing information from the other two detector volumes. All muons are fit under the hypothesis that they are through-going and ultrarelativistic. If the energy depositions suggest that the muon may have stopped, the reconstruction fits also for this hypothesis and chooses between the two via the relative goodness-of-fit. In the ideal case of a through-going muon intersecting the center of the detector, the resolution is ~40 mm in each transverse dimension. High quality muon reconstruction is an important tool for reducing the impact of the cosmogenic isotope background in Double Chooz.

physics.ins-det↗
arXiv2014

Background-independent measurement of $θ_{13}$ in Double Chooz

The oscillation results published by the Double Chooz collaboration in 2011 and 2012 rely on background models substantiated by reactor-on data. In this analysis, we present a background-model-independent measurement of the mixing angle $θ_{13}$ by including 7.53 days of reactor-off data. A global fit of the observed neutrino rates for different reactor power conditions is performed, yielding a measurement of both $θ_{13}$ and the total background rate. The results on the mixing angle are improved significantly by including the reactor-off data in the fit, as it provides a direct measurement of the total background rate. This reactor rate modulation analysis considers antineutrino candidates with neutron captures on both Gd and H, whose combination yields $\sin^2(2θ_{13})=$ 0.102 $\pm$ 0.028(stat.) $\pm$ 0.033(syst.). The results presented in this study are fully consistent with the ones already published by Double Chooz, achieving a competitive precision. They provide, for the first time, a determination of $θ_{13}$ that does not depend on a background model.

hep-ex↗
arXiv2013

Laboratory Studies on the Removal of Radon-Born Lead from KamLAND's Organic Liquid Scintillator

The removal of radioactivity from liquid scintillator has been studied in preparation of a low background phase of KamLAND. This paper describes the methods and techniques developed to measure and efficiently extract radon decay products from liquid scintillator. We report the radio-isotope reduction factors obtained when applying various extraction methods. During this study, distillation was identified as the most efficient method for removing radon daughters from liquid scintillator.

physics.ins-det↗
arXiv2013

Baryon Number Violation

This report, prepared for the Community Planning Study - Snowmass 2013 - summarizes the theoretical motivations and the experimental efforts to search for baryon number violation, focussing on nucleon decay and neutron-antineutron oscillations. Present and future nucleon decay search experiments using large underground detectors, as well as planned neutron-antineutron oscillation search experiments with free neutron beams are highlighted.

hep-ph↗
arXiv2013

The OscSNS White Paper

There exists a need to address and resolve the growing evidence for short-baseline neutrino oscillations and the possible existence of sterile neutrinos. Such non-standard particles require a mass of $\sim 1$ eV/c$^2$, far above the mass scale associated with active neutrinos, and were first invoked to explain the LSND $\bar ν_μ\rightarrow \bar ν_e$ appearance signal. More recently, the MiniBooNE experiment has reported a $2.8 σ$ excess of events in antineutrino mode consistent with neutrino oscillations and with the LSND antineutrino appearance signal. MiniBooNE also observed a $3.4 σ$ excess of events in their neutrino mode data. Lower than expected neutrino-induced event rates using calibrated radioactive sources and nuclear reactors can also be explained by the existence of sterile neutrinos. Fits to the world's neutrino and antineutrino data are consistent with sterile neutrinos at this $\sim 1$ eV/c$^2$ mass scale, although there is some tension between measurements from disappearance and appearance experiments. In addition to resolving this potential major extension of the Standard Model, the existence of sterile neutrinos will impact design and planning for all future neutrino experiments. It should be an extremely high priority to conclusively establish if such unexpected light sterile neutrinos exist. The Spallation Neutron Source (SNS) at Oak Ridge National Laboratory, built to usher in a new era in neutron research, provides a unique opportunity for US science to perform a definitive world-class search for sterile neutrinos.

physics.ins-det↗
arXiv2013

First Measurement of θ_13 from Delayed Neutron Capture on Hydrogen in the Double Chooz Experiment

The Double Chooz experiment has determined the value of the neutrino oscillation parameter $θ_{13}$ 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 $\sin^2 2θ_{13}=0.097\pm 0.034(stat.) \pm 0.034 (syst.)$, excluding the no-oscillation hypothesis at 2.0 σ. This result is consistent with previous measurements of $\sin^2 2θ_{13}$.

hep-ex↗
arXiv2013

Whitepaper on the DAEdALUS Program

This whitepaper describes the status of the DAEdALUS program for development of high power cyclotrons as of the time of the final meeting of the Division of Particles and Fields 2013 Community Study ("Snowmass"). We report several new results, including a measurement capability between 4 and 12 degrees on the CP violating parameter in the neutrino sector. Past results, including the capability of the IsoDAR high Dm^2 antielectron neutrino disappearance search, are reviewed. A discussion of the R&D successes, including construction of a beamline teststand, and future plans are provided. This text incorporates short whitepapers written for subgroups in the Intensity Frontier and Frontier Capabilities Working Groups that are available on the Snowmass website.

physics.acc-ph↗
arXiv2012

First Test of Lorentz Violation with a Reactor-based Antineutrino Experiment

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 (SME), we set the first limits on fourteen Lorentz violating coefficients associated with transitions between electron and tau flavor, and set two competitive limits associated with transitions between electron and muon flavor.

hep-ex↗
arXiv2012

Proposal for an Electron Antineutrino Disappearance Search Using High-Rate 8Li Production and Decay

This paper introduces a novel, high-intensity source of electron antineutrinos from the production and subsequent decay of 8Li. When paired with an existing ~1 kton scintillator-based detector, this =6.4 MeV source opens a wide range of possible searches for beyond standard model physics via studies of the inverse beta decay interaction. In particular, the experimental design described here has unprecedented sensitivity to electron antineutrino disappearance at $Δm^2\sim$ 1 eV$^2$ and features the ability to distinguish between the existence of zero, one, and two sterile neutrinos.

hep-ex↗
arXiv2012

Direct Measurement of Backgrounds using Reactor-Off Data in Double Chooz

Double Chooz is unique among modern reactor-based neutrino experiments studying $\bar ν_e$ 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$\pm$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.

hep-ex↗
arXiv2012

Cost-effective Design Options for IsoDAR

This whitepaper reviews design options for the IsoDAR electron antineutrino source. IsoDAR is designed to produce $2.6 \times 10^{22}$ electron antineutrinos per year with an average energy of 6.4 MeV, using isotope decay-at-rest. Aspects which must be balanced for cost-effectiveness include: overall cost; rate and energy distribution of the electron antineutrino flux and backgrounds; low technical risk; compactness; simplicity of underground construction and operation; reliability; value to future neutrino physics programs; and value to industry. We show that the baseline design outlined here is the most cost effective.

physics.acc-ph↗
arXiv2012

Reactor electron antineutrino disappearance in the Double Chooz experiment

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 2θ13 = 0.109 \pm 0.030(stat) \pm 0.025(syst). The data exclude the no-oscillation hypothesis at 99.8% CL (2.9σ).

hep-ex↗
arXiv2012

Indication for the disappearance of reactor electron antineutrinos in the Double Chooz experiment

The Double Chooz Experiment presents an indication of reactor electron antineutrino disappearance consistent with neutrino oscillations. A ratio of 0.944 $\pm$ 0.016 (stat) $\pm$ 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 $\pm$ 0.041 (stat) $\pm$ 0.030 (syst), or, at 90% CL, 0.015 $<$ \sang $\ <$ 0.16.

hep-ex↗
arXiv2011

Measurement of the 8B Solar Neutrino Flux with the KamLAND Liquid Scintillator Detector

We report a measurement of the neutrino-electron elastic scattering rate from 8B solar neutrinos based on a 123 kton-day exposure of KamLAND. The background-subtracted electron recoil rate, above a 5.5 MeV analysis threshold is 1.49+/-0.14(stat)+/-0.17(syst) events per kton-day. Interpreted as due to a pure electron flavor flux with a 8B neutrino spectrum, this corresponds to a spectrum integrated flux of 2.77+/-0.26(stat)+/-0.32(syst) x 10^6 cm^-2s^-1. The analysis threshold is driven by 208Tl present in the liquid scintillator, and the main source of systematic uncertainty is due to background from cosmogenic 11Be. The measured rate is consistent with existing measurements and with Standard Solar Model predictions which include matter enhanced neutrino oscillation.

hep-ex↗
arXiv2008

DUSEL Theory White Paper

The NSF has chosen the site for the Deep Underground Science and Engineering Laboratory (DUSEL) to be in Lead, South Dakota. In fact, the state of South Dakota has already stepped up to the plate and contributed its own funding for the proposed lab, see http://www.sanfordlaboratoryathomestake.org/index.html. The final decision by NSF for funding the Initial Suite of Experiments for DUSEL will be made early in 2009. At that time the NSF Science Board must make a decision. Of order 200 experimentalists have already expressed an interest in performing experiments at DUSEL. In order to assess the interest of the theoretical community, the Center for Cosmology and Astro-Particle Physics (CCAPP) at The Ohio State University (OSU) organized a 3-day DUSEL Theory Workshop in Columbus, Ohio from April 4 - 6, 2008. The workshop focused on the scientific case for six proposed experiments for DUSEL: long baseline neutrino oscillations, proton decay, dark matter, astrophysical neutrinos, neutrinoless double beta decay and N-Nbar oscillations. The outcome of this workshop is the DUSEL Theory White paper addressing the scientific case at a level which may be useful in the decision making process for policy makers at the NSF and in the U.S. Congress. In order to assess the physics interest in the DUSEL project we have posted the DUSEL Theory White paper on the following CCAPP link http://ccapp.osu.edu/whitepaper.html . Please read the white paper and, if you are interested, use the link to show your support by co-signing the white paper.

hep-ph↗
arXiv2004

Proposal for U.S. participation in Double-CHOOZ: A New theta-13 Experiment at the Chooz Reactor

It has recently been widely recognized that a reactor anti-neutrino disappearance experiment with two or more detectors is one of the most cost-effective ways to extend our reach in sensitivity for the neutrino mixing angle theta-13 without ambiguities from CP violation and matter effects. The physics capabilities of a new reactor experiment together with superbeams and neutrino factories have also been studied but these latter are considered by many to be more ambitious projects due to their higher costs, and hence to be farther in the future. We propose to contribute to an international collaboration to modify the existing neutrino physics facility at the Chooz-B Nuclear Power Station in France. The experiment, known as Double-CHOOZ, is expected to reach a sensitivity of sine squared of twice the mixing angle > 0.03 over a three year run, 2008-2011. This would cover roughly 85% of the remaining allowed region. The costs and time to first results for this critical parameter can be minimized since our project takes advantage of an existing infrastructure.

hep-ex↗