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Measurement of the asymmetry in the decay Antiomega+ ---> Antilambda K+ ---> anti-p pi+ K+

Description: The asymmetry in the {bar p} angular distribution in the sequential decay {bar {Omega}}{sup +} {yields} {bar {Lambda}}K{sup +} {yields} {bar p}{pi}{sup +}K{sup +} has been measured to be {bar {alpha}}{sub {Omega}}{bar {alpha}}{sub {Lambda}} = [+1.16{+-}0.18(stat){+-}0.17(syst)]x10{sup -2} using 1.89x10{sup 6} unpolarized {bar {Omega}}{sup +} decays recorded by the Hyper CP (E871) experiment at Fermilab. Using the known value of {alpha}{sub {Lambda}}, and assuming that {bar {alpha}}{sub {Lambda}} = -{alpha}{sub {Lambda}}, {bar {alpha}}{sub {Omega}} = [-1.81{+-}0.28(stat){+-}0.26(syst)]x10{sup -2}. A comparison between this measurement of {bar {alpha}}{sub {Omega}}{bar {alpha}}{sub {Lambda}} and recent measurements of {alpha}{sub {Omega}}{alpha}{sub {Lambda}} made by HyperCP shows no evidence of a violation of CP symmetry.
Date: January 1, 2006
Creator: Lu, L.C.; Burnstein, R.A.; Chakravorty, A.; Chen, Y.C.; Choong, W.S.; Clark, K. et al.
Partner: UNT Libraries Government Documents Department

Report of the APS Neutrino Study Reactor Working Group

Description: The worldwide program to understand neutrino oscillations and determine the neutrino mixing parameters, CP violating effects, and mass hierarchy will require a broad combination of measurements. The group believes that a key element of this future neutrino program is a multi-detector neutrino experiment (with baselines of {approx} 200 m and {approx} 1.5 km) with a sensitivity of sin{sup 2} 2{theta}{sub 13} = 0.01. In addition to oscillation physics, the reactor experiment may provide interesting measurements of sin{sup 2} {theta}{sub W} at Q{sup 2} = 0, neutrino couplings, magnetic moments, and mixing with sterile neutrino states. {theta}{sub 13} is one of the twenty-six parameters of the standard model, the best model of electroweak interactions for energies below 100 GeV and, as such, is worthy of a precision measurement independent of other considerations. A reactor experiment of the proposed sensitivity will allow a measurement of {theta}{sub 13} with no ambiguities and significantly better precision than any other proposed experiment, or will set limits indicating the scale of future experiments required to make progress. Figure 1 shows a comparison of the sensitivity of reactor experiments of different scales with accelerator experiments for setting limits on sin{sup 2} 2{theta}{sub 13} if the mixing angle is very small, or for making a measurement of sin{sup 2} 2{theta}{sub 13} if the angle is observable. A reactor experiment with a 1% precision may also resolve the degeneracy in the {theta}{sub 23} parameter when combined with long-baseline accelerator experiments. In combination with long-baseline measurements, a reactor experiment may give early indications of CP violation and the mass hierarchy. The combination of the T2K and Nova long-baseline experiments will be able to make significant measurements of these effects if sin{sup 2} 2{theta}{sub 13} > 0.05 and with enhanced beam rates can improve their reach to the sin{sup 2} 2{theta}{sub ...
Date: October 28, 2004
Creator: Abouzaid, E.; Anderson, K.; Barenboim, G.; Berger, B.; Blucher, E.; Bolton, T. et al.
Partner: UNT Libraries Government Documents Department

Search for CP violation in hyperon decays.

Description: Direct CP violation in nonleptonic hyperon decays can be established by comparing the decays of hyperons and anti-hyperons. For {Xi} decay to {Lambda} {pi} followed by {Lambda} to p{pi}, the proton distribution in the rest frame of Lambda is governed by the product of the decay parameters {alpha}{sub {Xi}} {alpha}{sub {Lambda}}. The asymmetry A{sub {Xi}{Lambda}}, proportional to the difference of {alpha}{sub {Xi}}{alpha}{sub {Lambda}} of the hyperon and anti-hyperon decays, vanishes if CP is conserved. We report on an analysis of a fraction of 1997 and 1999 data collected by the Hyper CP (E871) collaboration during the fixed-target runs at Fermilab. The preliminary measurement of the asymmetry is {Alpha}{sub {Xi}{Lambda}} = [-7 {+-} 12(stat) {+-} 6.2(sys)] x 10{sup -4}, an order of magnitude better than the present limit.
Date: October 25, 2002
Creator: Zyla, Piotr; Chan, A.; Chen, Y.C.; Ho, C.; Teng, P.K.; Choong, W.S. et al.
Partner: UNT Libraries Government Documents Department

Beauty and charm production from Fermilab experiment 789

Description: Experiment 789 is a fixed-target experiment at Fermilab designed to study low-multiplicity decays of charm and beauty. During the 1991 run. E789 collected {approx} 10{sup 9} events using an 800 GeV proton beam incident upon gold and beryllium targets. Analyses of these data include searches for b {yields} J/{psi}+{Chi} decays and {Alpha}- dependence measurements of neutral D meson production. Preliminary results from the 1991 run are presented in this paper.
Date: June 1, 1993
Creator: Jansen, D.M.; Boissevain, J.; Carey, T.A.; Jeppesen, R.G.; Kapustinsky, J.S.; Lane, D.W. 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

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