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Enhanced Constraints on theta13 from A Three-Flavor Oscillation Analysis of Reactor Antineutrinos at KamLAND

Description: We present new constraints on the neutrino oscillation parameters {Delta}m{sub 21}{sup 2}, {theta}{sub 12}, and {theta}{sub 13} from a three-flavor analysis of solar and KamLAND data. The KamLAND data set includes data acquired following a radiopurity upgrade and amounts to a total exposure of 3.49 x 10{sup 32} target-proton-year. Under the assumption of CPT invariance, a two-flavor analysis ({theta}{sub 13} = 0) of the KamLAND and solar data yields the best-fit values tan{sup 2} {theta}{sub 12} = 0.444{sub -0.030}{sup +0.036} and {Delta}m{sub 21}{sup 2} = 7.50{sub -0.20}{sup +0.19} x 10{sup -5} eV{sup 2}; a three-flavor analysis with {theta}{sub 13} as a free parameter yields the best-fit values tan{sup 2} {theta}{sub 12} = 0.452{sub -0.033}{sup +0.035}, {Delta}m{sub 21}{sup 2} = 7.50{sub -0.20}{sup +0.19} x 10{sup -5}eV{sup 2}, and sin{sup 2} {theta}{sub 13} = 0.020{sub -0.016}{sup +0.016}. This {theta}{sub 13} interval is consistent with other recent work combining the CHOOZ, atmospheric and long-baseline accelerator experiments. We also present a new global {theta}{sub 13} analysis, incorporating the CHOOZ, atmospheric and accelerator data, which indicates sin{sup 2} {theta}{sub 13} = 0.017{sub -0.009}{sup +0.010}, a nonzero value at the 93% C.L. This finding will be further tested by upcoming accelerator and reactor experiments.
Date: September 24, 2010
Creator: Collaboration, The KamLAND; Gando, A.; Gando, Y.; Ichimura, K.; Ikeda, H.; Inoue, K. et al.
Partner: UNT Libraries Government Documents Department

A study of extraterrestrial antineutrino sources with the KamLAND detector

Description: We present the results of a search for extraterrestrial electron antineutrinos ({bar {nu}}{sub e}'s) in the energy range 8.3 MeV < E{sub {bar {nu}}}{sub e} < 30.8 MeV using the KamLAND detector. In an exposure of 4.53 kton-year, we identify 25 candidate events. All of the candidate events can be attributed to background, most importantly neutral current atmospheric neutrino interactions, setting an upper limit on the probability of {sup 8}B solar {nu}{sub e}'s converting into {bar {nu}}{sub e}'s at 5.3 x 10{sup -5} (90% C.L.). The present data also allows us to set more stringent limits on the diffuse supernova neutrino flux and on the annihilation rates for light dark matter particles.
Date: May 18, 2011
Creator: Collaboration, The KamLAND; Gando, A.; Gando, Y.; Ichimura, K.; Ikeda, H.; Inoue, K. et al.
Partner: UNT Libraries Government Documents Department

LSND neutrino oscillation results

Description: The LSND experiment at Los Alamos has conducted searches for {anti {nu}}{sub {mu}} {r_arrow} {anti {nu}}{sub e} oscillations using {anti {nu}}{sub {mu}} from U{sup +} decay at rest and for {nu}{sub {mu}} {r_arrow} {nu}{sub e} oscillations using {nu}{sub {mu}} from {pi}{sup +} decay in flight. For the {anti {nu}}{sub {mu}} {r_arrow} {anti {nu}}{sub e} search, a total excess of 51.8{sub {minus}16.9}{sup +18.7} {+-} 8.0 events is observed with e{sup +} energy between 20 and 60 MeV, while for the {nu}{sub {mu}} {r_arrow} {nu}{sub e} search, a total excess of 18.1 {+-} 6.6 {+-} 4.0 events is observed with e{sup {minus}} energy between 60 and 200 MeV. If attributed to neutrino oscillations, these excesses correspond to oscillation probabilities (averaged over the experimental energies and spatial acceptances) of (0.31 {+-} 0.12 {+-} 0.05)% and (0.26 {+-} 0.10 {+-} 0.05)%, respectively.
Date: June 1, 1997
Creator: Louis, W.C. & Collaboration, LSND
Partner: UNT Libraries Government Documents Department

Antineutrino Oscillations in the Atmospheric Sector

Description: This thesis presents measurements of the oscillations of muon antineutrinos in the atmospheric sector, where world knowledge of antineutrino oscillations lags well behind the knowledge of neutrinos, as well as a search for {nu}{sub {mu}} {yields} {bar {nu}}{sub {mu}} transitions. Differences between neutrino and antineutrino oscillations could be a sign of physics beyond the Standard Model, including non-standard matter interactions or the violation of CPT symmetry. These measurements leverage the sign-selecting capabilities of the magnetized steel-scintillator MINOS detectors to analyze antineutrinos from the NuMI beam, both when it is in neutrino-mode and when it is in antineutrino-mode. Antineutrino oscillations are observed at |{Delta}{bar m}{sub atm}{sup 2}| = (3.36{sub -0.40}{sup +0.46}(stat) {+-} 0.06(syst)) x 10{sup -3} eV{sup 2} and sin{sup 2}(2{bar {theta}}{sub 23}) = 0.860{sub -0.12}{sup +0.11}(stat) {+-} 0.01(syst). The oscillation parameters measured for antineutrinos and those measured by MINOS for neutrinos differ by a large enough margin that the chance of obtaining two values as discrepant as those observed is only 2%, assuming the two measurements arise from the same underlying mechanism, with the same parameter values. No evidence is seen for neutrino-to-antineutrino transitions.
Date: May 1, 2011
Creator: Himmel, Alexander I. & /Caltech
Partner: UNT Libraries Government Documents Department

Searches for New Physics at MiniBooNE: Sterile Neutrinos and Mixing Freedom

Description: The MiniBooNE experiment was designed to perform a search for {nu}{sub {mu}} {yields} {nu}{sub e} oscillations in a region of {Delta}m{sup 2} and sin{sup 2} 2{theta} very different from that allowed by standard, three-neutrino oscillations, as determined by solar and atmospheric neutrino experiments. This search was motivated by the LSND experimental observation of an excess of {bar {nu}}{sub e} events in a {bar {nu}}{sub {mu}} beam which was found compatible with two-neutrino oscillations at {Delta}m{sup 2} {approx} 1 eV{sup 2} and sin{sup 2} 2{theta} < 1%. If confirmed, such oscillation signature could be attributed to the existence of a light, mostly-sterile neutrino, containing small admixtures of weak neutrino eigenstates. In addition to a search for {nu}{sub {mu}} {yields} {nu}{sub e} oscillations, MiniBooNE has also performed a search for {bar {nu}}{sub {mu}} {yields} {bar {nu}}{sub e} oscillations, which provides a test of the LSND two-neutrino oscillation interpretation that is independent of CP or CPT violation assumptions. This dissertation presents the MiniBooNE {nu}{sub {mu}} {yields} {nu}{sub e} and {bar {nu}}{sub {mu}} {yields} {bar {nu}}{sub e} analyses and results, with emphasis on the latter. While the neutrino search excludes the two-neutrino oscillation interpretation of LSND at 98% C.L., the antineutrino search shows an excess of events which is in agreement with the two-neutrino {bar {nu}}{sub {mu}} {yields} {bar {nu}}{sub e} oscillation interpretation of LSND, and excludes the no oscillations hypothesis at 96% C.L. Even though the neutrino and antineutrino oscillation results from MiniBooNE disagree under the single sterile neutrino oscillation hypothesis, a simple extension to the model to include additional sterile neutrino states and the possibility of CP violation allows for differences between neutrino and antineutrino oscillation signatures. In view of that, the viability of oscillation models with one or two sterile neutrinos is investigated in global fits to MiniBooNE and LSND data, ...
Date: July 1, 2010
Creator: Karagiorgi, Georgia S. & /MIT
Partner: UNT Libraries Government Documents Department

Searches for Rare Leptonic and Semileptonic Charm Decays at BaBar

Description: Recent results from leptonic and semi-leptonic charm decays at the BABAR B-factory are presented. The measurement of f{sub D{sub s}} from the D{sub s}{sup +} {yields} {mu}{sup +}{nu} channel is presented. Form-factor studies from the D{sup 0} {yields} K{sup +}e{sup -}{bar {nu}}{sub e} channel are described along with a search for flavor-changing neutral-current X{sub c}{sup +} {yields} h{sup +}{ell}{sup +}{ell}{prime}{sup -} decays.
Date: January 17, 2007
Creator: Jackson, Paul D. & U., /Ohio State
Partner: UNT Libraries Government Documents Department


Description: This document describes the design of the Daya Bay reactor neutrino experiment. Recent discoveries in neutrino physics have shown that the Standard Model of particle physics is incomplete. The observation of neutrino oscillations has unequivocally demonstrated that the masses of neutrinos are nonzero. The smallness of the neutrino masses (<2 eV) and the two surprisingly large mixing angles measured have thus far provided important clues and constraints to extensions of the Standard Model. The third mixing angle, {delta}{sub 13}, is small and has not yet been determined; the current experimental bound is sin{sup 2} 2{theta}{sub 13} < 0.17 at 90% confidence level (from Chooz) for {Delta}m{sub 31}{sup 2} = 2.5 x 10{sup -3} eV{sup 2}. It is important to measure this angle to provide further insight on how to extend the Standard Model. A precision measurement of sin{sup 2} 2{theta}{sub 13} using nuclear reactors has been recommended by the 2004 APS Multi-divisional Study on the Future of Neutrino Physics as well as a recent Neutrino Scientific Assessment Group (NUSAG) report. We propose to perform a precision measurement of this mixing angle by searching for the disappearance of electron antineutrinos from the nuclear reactor complex in Daya Bay, China. A reactor-based determination of sin{sup 2} 2{theta}{sub 13} will be vital in resolving the neutrino-mass hierarchy and future measurements of CP violation in the lepton sector because this technique cleanly separates {theta}{sub 13} from CP violation and effects of neutrino propagation in the earth. A reactor-based determination of sin{sup 2} 2{theta}{sub 13} will provide important, complementary information to that from long-baseline, accelerator-based experiments. The goal of the Daya Bay experiment is to reach a sensitivity of 0.01 or better in sin{sup 2} 2{theta}{sub 13} at 90% confidence level.
Date: October 16, 2006
Creator: KETTELL, S. & AL., ET
Partner: UNT Libraries Government Documents Department

First Observation of Accelerator Muon Antineutrinos in MINOS

Description: We report the first direct observation of muon antineutrinos in the MINOS Far Detector in the current muon-neutrino dominated beam. The magnetic field of the detector is utilized to separate muon neutrinos and antineutrinos event-by-event by identifying the charge sign of the muon created in charged-current interactions. We present preliminary results on the {bar {nu}}{sub {mu}} oscillation parameters as well as limit on the fraction of neutrinos that disappear and reappear as antineutrinos. We also discuss the prospect of the measurement when the polarity of the magnetic focusing horns will be reversed to create a dedicated muon antineutrino beam.
Date: October 1, 2009
Creator: Danko, Istvan
Partner: UNT Libraries Government Documents Department

Letter of Intent to Build a MiniBooNE Near Detector:BooNE

Description: There is accumulating evidence for a difference between neutrino and antineutrino oscillations at the {approx}1 eV{sup 2} scale. The MiniBooNE experiment observes an unexplained excess of electron-like events at low energies in neutrino mode, which may be due, for example, to either a neutral current radiative interaction, sterile neutrino decay, or to neutrino oscillations involving sterile neutrinos and which may be related to the LSND signal. No excess of electron-like events (-0.5 {+-} 7.8 {+-} 8.7), however, is observed so far at low energies in antineutrino mode. Furthermore, global 3+1 and 3+2 sterile neutrino fits to the world neutrino and antineutrino data suggest a difference between neutrinos and antineutrinos with significant (sin{sup 2} 2{theta}{sub {mu}{mu}} {approx} 35%) {bar {nu}}{sub {mu}} disappearance. In order to test whether the low-energy excess is due to neutrino oscillations and whether there is a difference between {nu}{sub {mu}} and {bar {nu}}{sub {mu}} disappearance, we propose building a second MiniBooNE detector at (or moving the existing MiniBooNE detector to) a distance of {approx}200 m from the Booster Neutrino Beam (BNB) production target. With identical detectors at different distances, most of the systematic errors will cancel when taking a ratio of events in the two detectors, as the neutrino flux varies as 1/r{sup 2} to a calculable approximation. This will allow sensitive tests of oscillations for both {nu}{sub e} and {bar {nu}} appearance and {nu}{sub {mu}} and {bar {nu}}{sub {mu}} disappearance. Furthermore, a comparison between oscillations in neutrino mode and antineutrino mode will allow a sensitive search for CP and CPT violation in the lepton sector at short baseline ({Delta}m{sup 2} > 0.1 eV{sup 2}). Finally, by comparing the rates for a neutral current (NC) reaction, such as NC {pi}{sup 0} scattering or NC elastic scattering, a direct search for sterile neutrinos will be made. The initial ...
Date: October 12, 2009
Creator: Stancu, I.; U., /Alabama; Djurcic, Z.; /Argonne; Smith, D.; U., /Embry-Riddle Aeronautical et al.
Partner: UNT Libraries Government Documents Department

Evidence for nu bar sub mu to nu bar sub e oscillations

Description: A search for {bar {nu}}{sub e}`s in excess of the number expected from conventional sources has been made using the Liquid Scintillator Neutrino Detector, located 30 m behind the LAMPF beam stop. The {bar {nu}}{sub e} are detected via {bar {nu}}{sub e}p{r_arrow}e{sup +}n with e{sup +} energy between 36 and 60 MeV, followed by a {gamma} from np{r_arrow}d{gamma} (2.2 MeV). Using strict cuts to identify {gamma}`s correlated with an e{sup +} yields 9 events with only 2.1{+-}0.3 background expected. A likelihood fit to the entire e{sup +} sample results in a total excess of 16.4{sup +9.7}{sub -8.9}{+-}3.3 events. If attributed to {bar {nu}}{sub {mu}}{r_arrow}{bar {nu}}{sub e} oscillations, this corresponds to an oscillation probability of (0.34{sup +0.200}{sub -0.18}{+-}0.07)%.
Date: December 31, 1995
Creator: Federspiel, F.J.
Partner: UNT Libraries Government Documents Department

LSND neutrino oscillation results

Description: The LSND experiment at Los Alamos has conducted a search for {anti v}{sub {mu}} {yields} {anti v}{sub e} oscillations using {anti v}{sub {mu}} from {mu}{sup +} decay at rest. The {anti v}{sub e} are detected via the reaction {anti v}{sub e} p {yields} e{sup +}n, correlated with the 2.2 MeV {gamma} from n p {yields} d {gamma}. The use of tight cuts to identify e{sup +} events with correlated {gamma} rays yielded 22 events with e{sup +} energy between 36 and 60 MeV and only 4.6 {+-} 0.6 background events. The probability that this excess is due entirely to a statistical fluctuation is 4.1 {times} 10{sup {minus}8}. A {chi}{sup 2} fit to the entire e{sup +} sample results in a total excess of 51.8{sub {minus}16.9}{sup +18.7} {+-} 8.0 events with e{sup +} energy between 20 and 60 MeV. If attributed to {anti v}{sub {mu}} {yields} {anti v}{sub e} oscillations, this corresponds to an oscillation probability (averaged over the experimental energy and spatial acceptance) of 0.31 {+-} 0.12 {+-} 0.05%.
Date: November 1, 1997
Creator: White, D.H. & Collaboration, LSND
Partner: UNT Libraries Government Documents Department


Description: Conceptual design studies are underway for both muon colliders and high-current non-colliding muon storage rings that have the potential to become the first true neutrino factories. Muon decays in long straight sections of the storage rings would produce uniquely intense and precisely characterized two-component neutrino beams--muon neutrinos plus electron antineutrinos from negative muon decays and electron neutrinos plus muon antineutrinos from positive muons. This article presents a long-term overview of the prospects for these facilities to greatly extend the capabilities for accelerator-based neutrino physics studies for both high rate and long baseline neutrino experiments. As the first major physics topic, recent experimental results involving neutrino oscillations have motivated a vigorous design effort towards dedicated neutrino factories that would store muon beams of energies 50 GeV or below. These facilities hold the promise of neutrino oscillation experiments with baselines up to intercontinental distances and utilizing well understood beams that contain, for the first time, a substantial component of multi-GeV electron-flavored neutrinos. In deference to the active and fast-moving nature of neutrino oscillation studies, the discussion of long baseline physics at neutrino factories has been limited to a concise general overview of the relevant theory, detector technologies, beam properties, experimental goals and potential physics capabilities. The remainder of the article is devoted to the complementary high rate neutrino experiments that would study neutrino-nucleon and neutrino-electron scattering and would be performed at high performance detectors placed as close as is practical to the neutrino production straight section of muon storage rings in order to exploit beams with transverse dimensions as small as a few tens of centimeters.
Date: May 11, 2000
Partner: UNT Libraries Government Documents Department

New Results from MiniBooNE: A Search for Electron Antineutrino Appearance at $\sim$1 eV$^2$

Description: These proceedings summarize the first MiniBooNE electron antineutrino appearance search results, corresponding to a data sample collected for 3.39 x 10{sup 20} protons on target (POT). The search serves as a direct test of the LSND oscillation signature, and provides complementary information which can be used in studies addressing the MiniBooNE neutrino-mode low-energy excess.
Date: October 1, 2009
Creator: Karagiorgi, Georgia S. & Collaboration, for the MiniBooNE
Partner: UNT Libraries Government Documents Department

Progress Towards Deployable Antineutrino Detectors for Reactor Safeguards

Description: Fission reactors emit large numbers of antineutrinos and this flux may be useful for the measurement of two quantities of interest for reactor safeguards: the reactor's power and plutonium inventory throughout its cycle. The high antineutrino flux and relatively low background rates means that simple cubic meter scale detectors at tens of meters standoff can record hundreds or thousands of antineutrino events per day. Such antineutrino detectors would add online, quasi-real-time bulk material accountancy to the set of reactor monitoring tools available to the IAEA and other safeguards agencies with minimal impact on reactor operations. Between 2003 and 2008, our LLNL/SNL collaboration successfully deployed several prototype safeguards detectors at a commercial reactor in order to test both the method and the practicality of its implementation in the field. Partially on the strength of the results obtained from these deployments, an Experts Meeting was convened by the IAEA Novel Technologies Group in 2008 to assess current antineutrino detection technology and examine how it might be incorporated into the safeguards regime. Here we present a summary of our previous deployments and discuss current work that seeks to provide expanded capabilities suggested by the Experts Panel, in particular aboveground detector operation.
Date: April 5, 2010
Creator: Bowden, N; Bernstein, A; Dazeley, S; Keefer, G; Reyna, D; Cabrera-Palmer, B et al.
Partner: UNT Libraries Government Documents Department

Atmospheric Neutrinos in the MINOS Far Detector

Description: The phenomenon of flavour oscillations of neutrinos created in the atmosphere was first reported by the Super-Kamiokande collaboration in 1998 and since then has been confirmed by Soudan 2 and MACRO. The MINOS Far Detector is the first magnetized neutrino detector able to study atmospheric neutrino oscillations. Although it was designed to detect neutrinos from the NuMI beam, it provides a unique opportunity to measure the oscillation parameters for neutrinos and anti-neutrinos independently. The MINOS Far Detector was completed in August 2003 and since then has collected 2.52 kton-years of atmospheric data. Atmospheric neutrino interactions contained within the volume of the detector are separated from the dominant background from cosmic ray muons. Thirty seven events are selected with an estimated background contamination of less than 10%. Using the detector's magnetic field, 17 neutrino events and 6 anti-neutrino events are identified, 14 events have ambiguous charge. The neutrino oscillation parameters for {nu}{sub {mu}} and {bar {nu}}{sub {mu}} are studied using a maximum likelihood analysis. The measurement does not place constraining limits on the neutrino oscillation parameters due to the limited statistics of the data set analysed. However, this thesis represents the first observation of charge separated atmospheric neutrino interactions. It also details the techniques developed to perform atmospheric neutrino analyses in the MINOS Far Detector.
Date: December 1, 2004
Creator: Howcroft, Caius L.F. & U., /Cambridge
Partner: UNT Libraries Government Documents Department


Description: We propose as the initial experiment in the new dichromatic V detector to make a systematic study of deep inelastic cross sections. This experiment will use the present target-detector remounted. A new magnet spectrometer system will be installed giving both better resolution and acceptance. An improved dichromatic beam will also give better information on the incident 13 neutrino energy. We propose 1000 hours of running with > 10{sup 13} ppp for this experiment.
Date: October 1, 1974
Creator: Barish, B.C.; Bartlett, J.F.; Bodek, A.; Brown, K.W.; Buchholz, D.; Merritt, F.S. et al.
Partner: UNT Libraries Government Documents Department

Prospects for antineutrino running at MiniBooNE

Description: MiniBooNE began running in antineutrino mode on 19 January, 2006. We describe the sensitivity of MiniBooNE to LSND-like {bar {nu}}{sub e} oscillations and outline a program of antineutrino cross-section measurements necessary for the next generation of neutrino oscillation experiments. We describe three independent methods of constraining wrong-sign (neutrino) backgrounds in an antineutrino beam, and their application to the MiniBooNE antineutrino analyses.
Date: February 1, 2006
Creator: Wascko, M.O. & U., /Louisiana State
Partner: UNT Libraries Government Documents Department

Evidence for {Kappa}{sup +} {r_arrow} {pi}{sup +}{nu}{anti {nu}}

Description: The first observation of the decay {Kappa}{sup +} {r_arrow} {pi}{sup +}{nu}{anti {nu}} has been reported. The E787 experiment presented evidence for the {Kappa}{sup +} {r_arrow} {pi}{sup +}{nu}{anti {nu}} decay, based on the observation of a single clean event from data collected during the 1995 run of the AGS (Alternating Gradient Synchrotron at Brookhaven National Laboratory). The branching ratio indicated by this observation, {Beta}({Kappa}{sup +} {r_arrow} {pi}{sup +}{nu}{anti {nu}}) = 4.2{sub {minus}3.5}{sup +9.7} {times} 10{sup {minus}10}, is consistent with the Standard Model expectation although the central experimental value is four times larger. The final E787 data sample, from the 1995--98 runs, should reach a sensitivity of about five times that of the 1995 run alone. A new experiment, E949, has been given scientific approval and should start data collection in 2001. It is expected to achieve a sensitivity of more than an order of magnitude below the prediction of the Standard Model.
Date: December 31, 1998
Creator: Kettell, S.
Partner: UNT Libraries Government Documents Department


Description: This paper presents the latest results from experiment E787, at Brookhaven National Laboratory, on K{sup +} {r_arrow} {pi}{sup +} {nu}{bar {nu}} and radiative K{sup +} decays. The result for K{sup +} {r_arrow} {pi}{sup +} {nu}{bar {nu}} uses data collected in runs taken during 1995, 1996 and 1997. In addition, they discuss plans for future measurements of K{sup +} {r_arrow} {pi}{sup +} {nu}{bar {nu}}.
Date: October 9, 2000
Creator: JAIN,V.
Partner: UNT Libraries Government Documents Department

Observation of the decay K{sup +} {r_arrow} {pi}{sup +} {nu}{bar {nu}}

Description: We have observed 1 event consistent with the signature expected of the rare decay of a positive kaon to a positive pion and a neutrino anti-neutrino pair. In the examined momentum region of 211 to 230 MeV/c in the center of mass of the kaon we estimated the backgrounds to be about 0.08 {+-} 0.03 events. From this observation we estimate the branching ratio to be 4.2{sub {minus}3.5}{sup +9.7} x 10{sup {minus}10}. In this presentation I will explain the experiment, and the analysis techniques. I will also discuss the expected improvements in the near future from the analysis of new data sets.
Date: January 5, 1999
Creator: DIWAN,M.B.
Partner: UNT Libraries Government Documents Department