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A search for. nu. sub e appearance from stopped. pi. sup + and. mu. sup + decay at LAMPF (Los Alamos Meson Physics Facility)

Description: We report on a recent search for {bar {nu}}{sub e} appearance from stopped {pi}{sup +} {yields} {mu}{sup +}{nu}{sub {mu}} and {mu}{sup +} {yields} e{sup +}{nu}{sub e}{bar {nu}}{sub {mu}} decay made by the LAMPF experiment E645. The appearance of {bar {nu}}{sub e} may occur from {bar {nu}}{sub {mu}} {yields} {bar {nu}}{sub e}, {nu}{sub e} {yields} {bar {nu}}{sub eL}, or {nu}{sub {mu}} {yields} {bar {nu}}{sub eL} oscillations. Appearance may also occur from rare {mu}{sup +} {yields} e{sup +}{bar {nu}}{sub e}{nu}{sub {mu}} decay, which is allowed by a multiplicative lepton charge conservation law. The neutrino energies range from E{sub {nu}} = 0 to 52.8MeV. The neutrino detector, which is located 26.1 meters from the neutrino source, consists of a segmented liquid scintillator and proportional drift tube central detector surrounded by both active and passive shielding. The central detector detects {bar {nu}}{sub e} through the {bar {nu}}{sub e}p {yields} ne{sup +} Charge Current (CC) reaction, which is signaled by the direct detection of the final state positron and neutron. The hydrogen-rich liquid scintillators act as free proton targets for the {bar {nu}}{sub e}p CC reaction. The neutrons are detected through radiative neutron capture on gadolinium. We find no evidence for {bar {nu}}{sub e} appearance in the first year of running. New limits on the {bar {nu}}{sub {mu}},{nu}{sub e},{nu}{sub {mu}} {yields} {bar {nu}}{sub e} oscillation parameters and the rare {mu}{sup +} {yields} e{sup +}{bar {nu}}{sub e}{nu}{sub {mu}} decay branching ratio are presented. 87 refs., 45 figs., 17 tabs.
Date: January 1, 1990
Creator: Fujikawa, B. K.
Partner: UNT Libraries Government Documents Department

Search for neutrino oscillations at LAMPF

Description: The decays of stopped pions in the LAMPF beam stop present a unique opportunity to probe neutrino oscillations in the mass region of deltam/sup 2/ approx.0.1eV/sup 2/ and mixing parameters as low was sin/sup 2/2THETA approx.10/sup -3/. The appearance of anti nu/sub e/ will be measured with high sensitivity by Experiment 645 during the run cycle that begins in the summer of 1986.
Date: January 1, 1986
Creator: Harper, R.W.; Ling, T.Y.; Mitchell, J.W.; Romanowski, T.A.; Smith, E.S.; Timko, M. et al.
Partner: UNT Libraries Government Documents Department

A New Limit on Time-Reversal Violation in Beta Decay

Description: We report the results of an improved determination of the triple correlation DP {center_dot} (p{sub e} x p{sub v}) that can be used to limit possible time-reversal invariance in the beta decay of polarized neutrons and constrain extensions to the Standard Model. Our result is D = (-0.96 {+-} 1.89(stat) {+-} 1.01(sys)) x 10{sup -4}. The corresponding phase between g{sub A} and g{sub V} is {phi}{sub AV} = 180.013{sup o} {+-} 0.028{sup o} (68% confidence level). This result represents the most sensitive measurement of D in nuclear beta decay.
Date: April 26, 2011
Creator: Mumm, H P; Chupp, T E; Cooper, R L; Coulter, K P; Freedman, S J; Fujikawa, B K et al.
Partner: UNT Libraries Government Documents Department

Measurement of the Double-Beta Decay Half-life of {sup 136}Xe in KamLAND-Zen

Description: We present results from the KamLAND-Zen double-beta decay experiment based on an exposure of 77.6 days with 129 kg of {sup 136}Xe. The measured two-neutrino double-beta decay half-life of {sup 136}Xe is T{sup 2{nu}}{sub 1/2} = 2:38 {+-}#6; 0:02(stat)#6;{+-}0.14(syst)#2;x10{sup 21} yr, consistent with a recent measurement by EXO-200. We also obtain a lower limit for the neutrinoless double-beta decay half-life, T{sup 0{nu}}{sub 1/2} > 5.7 x#2; 10{sup 24} yr at 90% C.L.
Date: January 23, 2012
Creator: Collaboration, KamLAND-Zen; Gando, A.; Gando, Y.; Hanakago, H.; Ikeda, H.; Inoue, K. et al.
Partner: UNT Libraries Government Documents Department

Measurement of the Parity Violating Asymmetry A

Description: The weak pion-nucleon coupling constant H{sub {pi}}{sup 1} remains poorly determined, despite many years of effort. The recent measurement of the {sup 133}Cs anapole moment has been interpreted to give a value of H{sub {pi}}{sup 1} almost an order of magnitude larger than the limit established in the {sup 18}F parity doublet experiments. A measurement of the gamma ray directional asymmetry A{sub {gamma}} for the capture of polarized neutrons by hydrogen has been proposed at Los Alamos National Laboratory. This experiment will determine H{sub {pi}}{sup 1} independent of nuclear structure effects. However, since the predicted asymmetry is small, A{sub {gamma}} {approximately} 5 x 10{sup {minus}8}, systematic effects must be reduced to < 5 x 10{sup {minus}9}. The design of the experiment will is presented, with an emphasis on the techniques used for controlling systematic errors.
Date: December 4, 1998
Creator: Wilburn, W. S.; Bazhenov, A.; Blessinger, C. S.; Bowman, J. D.; Chupp, T. E.; Coulter, K. P. 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

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

Measurement of the 8B Solar Neutrino Flux with KamLAND

Description: We report a measurement of the neutrino-electron elastic scattering rate from {sup 8}B 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 {sup 8}B neutrino spectrum, this corresponds to a spectrum integrated flux of 2.77 {+-} 0.26(stat) {+-} 0.32(syst) x 10{sup 6} cm{sup -2}s{sup -1}. The analysis threshold is driven by {sup 208}Tl present in the liquid scintillator, and the main source of systematic uncertainty is due to background from cosmogenic {sup 11}Be. The measured rate is consistent with existing measurements and with standard solar model predictions which include matter-enhanced neutrino oscillation.
Date: June 4, 2011
Creator: Abe, S.; Furuno, K.; Gando, A.; Gando, Y.; Ichimura, K.; Ikeda, H. et al.
Partner: UNT Libraries Government Documents Department

Study of the Production of Radioactive Isotopes through Cosmic Muon Spallation in KamLAND

Description: Radioactive isotopes produced through cosmic muon spallation are a background for rare event detection in {nu} detectors, double-beta-decay experiments, and dark-matter searches. Understanding the nature of cosmogenic backgrounds is particularly important for future experiments aiming to determine the pep and CNO solar neutrino fluxes, for which the background is dominated by the spallation production of {sup 11}C. Data from the Kamioka Liquid scintillator Anti-Neutrino Detector (KamLAND) provides valuable information for better understanding these backgrounds, especially in liquid scintillator, and for checking estimates from current simulations based upon MUSIC, FLUKA, and Geant4. Using the time correlation between detected muons and neutron captures, the neutron production yield in the KamLAND liquid scintillator is measured to be (2.8 {+-} 0.3) x 10{sup -4} n/({mu} {center_dot} (g/cm{sup 2})). For other isotopes, the production yield is determined from the observed time correlation related to known isotope lifetimes. We find some yields are inconsistent with extrapolations based on an accelerator muon beam experiment.
Date: June 30, 2009
Creator: Collaboration, KamLAND; Abe, S.; Enomoto, S.; Furuno, K.; Gando, Y.; Ikeda, H. et al.
Partner: UNT Libraries Government Documents Department

The KamLAND Full-Volume Calibration System

Description: We have successfully built and operated a source deployment system for the KamLAND detector. This system was used to position radioactive sources throughout the delicate 1-kton liquid scintillator volume, while meeting stringent material cleanliness, material compatibility, and safety requirements. The calibration data obtained with this device were used to fully characterize detector position and energy reconstruction biases. As a result, the uncertainty in the size of the detector fiducial volume was reduced by a factor of two. Prior to calibration with this system, the fiducial volume was the largest source of systematic uncertainty in measuring the number of antineutrinos detected by KamLAND. This paper describes the design, operation and performance of this unique calibration system.
Date: March 5, 2009
Creator: Collaboration, KamLAND; Berger, B. E.; Busenitz, J.; Classen, T.; Decowski, M. P.; Dwyer, D. A. et al.
Partner: UNT Libraries Government Documents Department

Sensitivity of CUORE to Neutrinoless Double-Beta Decay

Description: In this paper, we study the sensitivity of CUORE, a bolometric double-beta decay experiment under construction at the Laboratori Nazionali del Gran Sasso in Italy. Two approaches to the computation of experimental sensitivity are discussed and compared, and the formulas and parameters used in the sensitivity estimates are provided. Assuming a background rate of 10{sup -2} cts/(keV kg y), we find that, after 5 years of live time, CUORE will have a 1#27;{sigma} sensitivity to the neutrinoless double-beta decay half-life of {caret T{sup 0{nu}}{sub 1/2}}(1{sigma}#27;) = 1.6x#2;10{sup 26} y and thus a potential to probe the effective Majorana neutrino mass down to 41-95 meV; the sensitivity at 1.64{sigma}#27;, which corresponds to 90% C.L., will be {caret T{sup 0{nu}}{sub 1/2}(1.64{sigma}#27;}) = 9.5x10{sup 25} y. This range is compared with the claim of observation of neutrinoless double-beta decay in {sup 76}Ge and the preferred range in the neutrino mass parameter space from oscillation results.
Date: November 23, 2011
Creator: CUORE; Alessandria, F.; Andreotti, E.; Ardito, R.; Arnaboldi, C.; Avignone III, F. T. et al.
Partner: UNT Libraries Government Documents Department

White paper report on using nuclear reactors to search for a value of theta13

Description: There has been superb progress in understanding the neutrino sector of elementary particle physics in the past few years. It is now widely recognized that the possibility exists for a rich program of measuring CP violation and matter effects in future accelerator {nu} experiments, which has led to intense efforts to consider new programs at neutrino superbeams, off-axis detectors, neutrino factories and beta beams. However, the possibility of measuring CP violation can be fulfilled only if the value of the neutrino mixing parameter {theta}{sub 13} is such that sin{sup 2} (2{theta}{sub 13}) greater than or equal to on the order of 0.01. The authors of this white paper are an International Working Group of physicists who believe that a timely new experiment at a nuclear reactor sensitive to the neutrino mixing parameter {theta}{sub 13} in this range has a great opportunity for an exciting discovery, a non-zero value to {theta}{sub 13}. This would be a compelling next step of this program. We are studying possible new reactor experiments at a variety of sites around the world, and we have collaborated to prepare this document to advocate this idea and describe some of the issues that are involved.
Date: February 26, 2004
Creator: Anderson, K.; Anjos, J.C.; Ayres, D.; Beacom, J.; Bediaga, I.; de Bellefon, A. et al.
Partner: UNT Libraries Government Documents Department