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LSND neutrino oscillation results

Description: In the past several years, a number of experiments have searched for neutrino oscillations, where a neutrino of one type (say {bar {nu}}{sub {mu}}) spontaneously transforms into a neutrino of another type (say {bar {nu}}{sub e}). For this phenomenon to occur, neutrinos must be massive and the apparent conservation law of lepton families must be violated. In 1995 the LSND experiment published data showing candidate events that are consistent with {bar {nu}}{sub {mu}} oscillations. Additional data are reported here which provide stronger evidence for neutrino oscillations.
Date: June 1, 1996
Creator: Louis, W.C.
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

MSW Effects in Vacuum Oscillations

Description: We point out that for solar neutrino oscillations with the mass-squared difference of Delta m^2 ~;; 10^-10 - 10^-9 eV^2, traditionally known as"vacuum oscillation'' range, the solar matter effects are non-negligible, particularly for the low energy pp neutrinos. One consequence of this is that the values of the mixing angle theta and pi/2-theta are not equivalent, leading to the need to consider the entire physical range of the mixing angle 0<=theta<=pi/2 when determining the allowed values of the neutrino oscillation parameters.
Date: February 6, 2000
Creator: Friedland, Alexander
Partner: UNT Libraries Government Documents Department

Stodolsky's theorem and neutrino oscillation phases-for pedestrians.

Description: Neutrino oscillations are experimentally observable only as a result of interference between neutrino states with different masses and the same energy. All interference effects between neutrino states having different energies are destroyed by the interaction between the incident neutrino and the neutrino detector. Erroneous results are frequently obtained by neglecting the neutrino-detector interactions.
Date: February 19, 2003
Creator: Lipkin, H. J.
Partner: UNT Libraries Government Documents Department

CPand t violation in neutrino oscillations

Description: In this short lecture, we discuss some basic phenomenological aspects of CP and T violation in neutrino oscillation. Using CP/T trajectory diagrams in the bi-probability space, we try to sketch out some essential features of the interplay between the effect of CP/T violating phase and that of the matter in neutrino oscillation.
Date: September 18, 2003
Creator: Minakata, Hisakazu; Nunokawa, Hiroshi & Parke, Stephen
Partner: UNT Libraries Government Documents Department

Development of a low-cost extruded scintillator with co-extruded reflector for the MINOS experiment

Description: The MINOS experiment is a long-baseline, neutrino-oscillation experiment. In total, 28,000 m{sup 2} of scintillator is needed for the experiment. This is almost 300 tons of finished scintillator. The solution has been the development of an extruded scintillator with a 2-mm deep grove in the upper surface for a wavelength-shifting fiber and a co-extruded TiO{sub 2} coating as a reflector. The TiO{sub 2} coating also allows the scintillator to be directly epoxied into panels. Production and quality control techniques are presented.
Date: December 11, 2000
Creator: al., David F. Anderson et
Partner: UNT Libraries Government Documents Department

Neutrino oscillation physics with BooNE

Description: A proposal was submitted to Fermilab for a Booster Neutrino Experiment (BooNE) to confirm the discovery of neutrino oscillations at LANL using a Liquid Scintillator Neutrino Detector (LSND). The location of the experiment at the Fermilab Booster will provide for higher signal rates than were possible at LSND by about an order of magnitude. BooNE will also provide an opportunity for observing the signal under very different conditions and with different systematics than were present at LSND. The muon collider will provide an opportunity to further explore this region of parameter space with a different set of systematics. Most important will be that the neutrino flux will be accurately known, since the current of the parent muon beam can be measured very precisely. This source will provide a and flux equal in magnitude and with easily calculable energy and spatial distributions.
Date: April 1, 1998
Creator: Stefanski, R.J.
Partner: UNT Libraries Government Documents Department

CPT Tests: Kaon vs neutrinos

Description: CPT violation has an impressive limit in the neutral kaon system |m(K{sup 0})-m({bar K}{sup 0})| < 10{sup -18} m{sub K} = 0.50 x 10{sup -18} GeV. However, if viewed as a constraint on the mass-squared, the bound appears weak, |m{sup 2}(K{sup 0})-m{sup 2}({bar K}{sup 0})| < 0.25 eV{sup 2}. the authors point out that neutrino oscillation offers better limits on CPT violation in this case. The comparison of solar and rector neutrino results puts the best limit on CPT violation by far, |{Delta}m{sub {nu}}{sup 2}-{Delta}m{sub {rho}}{sup 2}| < 1.3 x 10{sup -3} eV{sup 2} (90% CL).
Date: July 9, 2003
Creator: Murayama, Hitoshi
Partner: UNT Libraries Government Documents Department

Long baseline neutrino oscillations: Parameter degeneracies and JHF/NuMI complementarity

Description: A summary of the parameter degeneracy issue for long baseline neutrino oscillations is presented and how a sequence of measurements can be used to resolve all degeneracies. Next, a comparison of the JHF and NuMI Off-Axis proposals is made with emphasis on how both experiments running neutrinos can distinguish between the normal and inverted hierarchies provided the E/L of NuMI is less than or equal to the E/L of JHF. Due to the space limitations of this proceedings only an executive style summary can be presented here, but the references and transparencies of the talk contain the detailed arguments.
Date: October 13, 2003
Creator: Parke, Stephen; Minakata, Hisakazu & Nunokawa, Hiroshi
Partner: UNT Libraries Government Documents Department

Prospects for next generation long-baseline oscillation experiments

Description: This document describes some of the exciting possibilities for the next steps in the field of long baseline neutrino oscillation measurements. Because the primary goals of these new experiments are so different from those of the current generation, one cannot simply increase the running time or detector mass of the current programs. There are several new strategies which have been discussed for taking the next steps: sometimes the detectors, sometimes the beamlines, and sometimes both are radically different from what is now in place.
Date: June 17, 2003
Creator: Harris, Deborah A
Partner: UNT Libraries Government Documents Department

Questions of Identity

Description: As an introduction to {nu}Fact '99, the ICFA/ECFA Workshop on Neutrino Factories Based on Muon Storage Rings, I place the issues of neutrino properties and neutrino oscillations in the broader context of fermion flavor.
Date: August 25, 1999
Creator: Quigg, Chris
Partner: UNT Libraries Government Documents Department

Baryon Triality And Neutrino Masses From An Anomalous FlavorU(1)

Description: We construct a concise U(1){sub X} Froggatt-Nielsen model in which baryon triality, a discrete gauge Z{sub 3}-symmetry, arises from U(1){sub X} breaking. The proton is thus stable, however, R-parity is violated. With the proper choice of U(1){sub X} charges we can obtain neutrino masses and mixings consistent with an explanation of the atmospheric and solar neutrino anomalies in terms of neutrino oscillations, with no right-handed neutrinos required. The only mass scale apart from M{sub grav} is m{sub soft}.
Date: August 15, 2007
Creator: Dreiner, Herbi K.; Luhn, Christoph; Murayama, Hitoshi & Thormeier,Marc
Partner: UNT Libraries Government Documents Department

LSND, SN1987A, and CPT violation

Description: We point out that neutrino events observed at Kamiokande andIMB from SN1987A disfavor the neutrino oscillation parameters preferredby the LSND experiment. For Delta m2>0 (the light side), theelectron neutrinos from the neutronization burst would be lost, while thefirst event at Kamiokande is quite likely to be due to an electronneutrino. For Delta m2<0 (the dark side), the average energy of thedominantly bar nu e events is already lower than the theoreticalexpectations, which would get aggravated by a complete conversion frombar nu mu to bar nu e. If taken seriously, the LSND data are disfavoredindependent of the existence of a sterile neutrino. A possible remedy isCPT violation, which allows different mass spectra for neutrinos andanti-neutrinos and hence can accommodate atmospheric, solar and LSND datawithout a sterile neutrino. If this is the case, Mini-BooNE must run inbar nu rather than the planned nu mode to test the LSND signal. Wespeculate on a possible origin of CPT violation.
Date: October 17, 2000
Creator: Murayama, Hitoshi & Yanagida, T.
Partner: UNT Libraries Government Documents Department

Towards a precision measurement of theta13 with reactor neutrinos: Initiatives in the United States

Description: Recent experimental results have provided unambiguous evidence that neutrinos have a small but finite mass and mix from one type into another. The phenomenon of neutrino mixing is characterized by the coupling between the neutrino flavor (nu e,mu,tau) and mass eigenstates (nu 1,2,3) and the associated mixing angles. Previous neutrino oscillation experiments have determined two of the three mixing angles in the neutrino mixing matrix, U MNSP. Using multiple neutrino detectors placed at different distances from a nuclear power plant, a future reactor neutrino experiment has the potential to discover and measure the coupling of the electron neutrino flavor to the third mass eigenstate, Ue3, the last undetermined element of the neutrino mixing matrix. In this paper we describe recent efforts in the US towards a next-generation experiment to measure theta13 with reactor neutrinos.
Date: September 12, 2004
Creator: Heeger, Karsten M.
Partner: UNT Libraries Government Documents Department

Measurement of theta{sub 13} with reactor neutrinos

Description: Recent experimental results have provided unambiguous evidence that neutrinos have a small but finite mass and mix from one type into another. The phenomenon of neutrino mixing is characterized by the coupling between the neutrino flavor (nu{sub e,mu,tau}) and mass eigenstates (nu{sub 1,2,3}) and the associated mixing angles. Previous neutrino oscillation experiments have determined two of the three mixing angles in the neutrino mixing matrix, U{sub MNSP}. Using multiple neutrino detectors placed at different distances from a nuclear power plant, a future reactor neutrino experiment has the potential to discover and measure the coupling of the electron neutrino flavor to the third mass eigenstate, U{sub e3}, the last undetermined element of the neutrino mixing matrix.
Date: July 13, 2004
Creator: Heeger, Karsten M.; Freedman, Stuart J.; Kadel, Richard W. & Luk, Kam-Biu
Partner: UNT Libraries Government Documents Department

Evidence for neutrino mass: A decade of discovery

Description: Neutrino mass and mixing are amongst the major discoveries of recent years. From the observation of flavor change in solar and atmospheric neutrino experiments to the measurements of neutrino mixing with terrestrial neutrinos, recent experiments have provided consistent and compelling evidence for the mixing of massive neutrinos. The discoveries at Super-Kamiokande, SNO, and KamLAND have solved the long-standing solar neutrino problem and demand that we make the first significant revision of the Standard Model in decades. Searches for neutrinoless double-beta decay probe the particle nature of neutrinos and continue to place limits on the effective mass of the neutrino. Possible signs of neutrinoless double-beta decay will stimulate neutrino mass searches in the next decade and beyond. I review the recent discoveries in neutrino physics and the current evidence for massive neutrinos.
Date: December 8, 2004
Creator: Heeger, Karsten M.
Partner: UNT Libraries Government Documents Department

Status of Neutrino Factory R&amp;D within the Muon Collaboration

Description: The authors describe the current status of the research within the Muon Collaboration towards realizing a Neutrino Factory. The authors describe briefly the physics motivation behind the neutrino factory approach to studying neutrino oscillations and the longer term goal of building the Muon Collider. The benefits of a step by step staged approach of building a proton driver, collecting and cooling muons followed by the acceleration and storage of cooled muons are emphasized. Several usages of cooled muons open up at each new stage in such an approach and new physics opportunities are realized at the completion of each stage.
Date: February 19, 2004
Creator: Raja, Rajendran
Partner: UNT Libraries Government Documents Department

MSW without matter

Description: We examine the effects of a scalar field, coupled only to neutrinos, on oscillations among weak interaction current eigenstates. The existence of a real scalar field is manifested as effective masses for the neutrino mass3 eigenstates, the same for F, as for v. Under some conditions, this can lead to a vanishing of {delta}m{sup 2}, giving rise to MSW-like effects. We present an idealized example and show that it may be possible to resolve the apparent discrepancy in spectra required by reprocess nucleosynthesis in the mantles of supernovae and by Solar neutrino solutions.
Date: September 1, 1996
Creator: Goldman, T.; McKellar, B.H.J. & Stephneson, G.J. Jr.
Partner: UNT Libraries Government Documents Department

Low energy solar neutrino experiments: The Soviet American Gallium Experiment (SAGE). Final report, August 12, 1988--October 31, 1994

Description: Two {sup 71}Ga experiments are currently in operation. The first is the 60 ton Soviet American Gallium Experiment (SAGE) at Baksan, which has recently reported a signal level of 73+18/{minus}16(stat)+5/{minus}7(syst) SNU; the second is the 30 ton GALLEX experiment at Gran Sasso, which sees 87{+-}14{+-}7 SNU. Both results are consistent, and both suggest a neutrino flux level low compared to the total expected from standard solar model calculations. It is not possible, however, to make a case for flux levels lower than the p-p prediction. Assuming the experiments are correct (Neutrino source calibrations are planned for both SAGE and GALLEX in the near future.), it is not at all clear yet whether the answer lies with the neutrino physics, solar physics, or a combination of both. Nevertheless, though solar model effects cannot be ruled out, if the Homestake and Kamiokande results are taken at face value, then these two experiments alone imply that neutrino oscillations or some similar particle physics result must be present to some degree. This report reviews the SAGE experiment and recent results. Non-radiochemical experiments are also discussed, with an emphasis on the Kamiokande water Cerenkov results.
Date: April 1, 1995
Partner: UNT Libraries Government Documents Department

LSND neutrino oscillation results

Description: The LSND (Liquid Scintillator Neutrino Detector) experiment at Los Alamos has conducted a search for muon antineutrino {r_arrow} electron antineutrino oscillations using muon neutrinos from antimuon decay at rest. The electron antineutrinos are detected via the reaction electron antineutrino + proton {r_arrow} positron + neutron, correlated with the 2.2-MeV gamma from neutron + proton {r_arrow} deuteron + gamma. The use of tight cuts to identify positron events with correlated gamma rays yields 22 events with positron 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 -8}. A chi-squared fit to the entire positron sample results in a total excess of 51.8 {sup +18.7}{sub -16.9} {+-} 8.0 events with positron energy between 20 and 60 MeV. If attributed to muon antineutrino {r_arrow} electron antineutrino oscillations, this corresponds to an oscillation probability (averaged over the experimental energy and spatial acceptance) of (0.31 {+-} 0.12 {+-} 0.05){percent}. 10 refs., 7 figs., 1 tab.
Date: October 1, 1996
Creator: Louis, W.C. & Collaboration, LSND
Partner: UNT Libraries Government Documents Department