857 research outputs found
The Search for Neutrino Oscillations numubar->nuebar with KARMEN
The neutrino experiment KARMEN is situated at the beam stop neutrino source
ISIS. It provides numu's, nue's and numubar's in equal intensities from the pi+
mu+ decay at rest (DAR). The oscillation channel numub->nueb is investigated in
the appearance mode with a 56t liquid scintillation calorimeter at a mean
distance of 17.7m from the nu source looking for p(nue,e+)n reactions. The
cosmic induced background for this oscillation search could be reduced by a
factor of 40 due to an additional veto counter installed in 1996. In the data
collected through 1997 and 1998 no potential oscillation event was observed.
Using a unified approach to small signals this leads to an upper limit for the
mixing angle of sin**2(2t) < 1.3x10^{-3} (90%CL) at large Dm**2. The excluded
area in (sin**2(2t),Dm**2) covers almost entirely the favored region defined by
the LSND numub->nueb evidence.Comment: Proceedings Contribution to Neutrino98 in Takayama, Japan, June 4-9,
1998; 13 pages, including 4 figure
Laser microscopy of tunneling magnetoresistance in manganite grain-boundary junctions
Using low-temperature scanning laser microscopy we directly image electric
transport in a magnetoresistive element, a manganite thin film intersected by a
grain boundary (GB). Imaging at variable temperature allows reconstruction and
comparison of the local resistance vs temperature for both, the manganite film
and the GB. Imaging at low temperature also shows that the GB switches between
different resistive states due to the formation and growth of magnetic domains
along the GB. We observe different types of domain wall growth; in most cases a
domain wall nucleates at one edge of the bridge and then proceeds towards the
other edge.Comment: 5 pages, 4 figures; submitted to Phys. Rev. Let
Sensitivity to the KARMEN Timing Anomaly at MiniBooNE
We present sensitivities for the MiniBooNE experiment to a rare exotic pion
decay producing a massive particle, Q^0. This type of decay represents one
possible explanation for the timing anomaly reported by the KARMEN
collaboration. MiniBooNE will be able to explore an area of the KARMEN signal
that has not yet been investigated
First-principles study of (BiScO3){1-x}-(PbTiO3){x} piezoelectric alloys
We report a first-principles study of a class of (BiScO3)_{1-x}-(PbTiO3)_x
(BS-PT) alloys recently proposed by Eitel et al. as promising materials for
piezoelectric actuator applications. We show that (i) BS-PT displays very large
structural distortions and polarizations at the morphotropic phase boundary
(MPB) (we obtain a c/a of ~1.05-1.08 and P_tet of ~1.1 C/m^2); (ii) the
ferroelectric and piezoelectric properties of BS-PT are dominated by the onset
of hybridization between Bi/Pb-6p and O-2p orbitals, a mechanism that is
enhanced upon substitution of Pb by Bi; and (iii) the piezoelectric responses
of BS-PT and Pb(Zr_{1-x}Ti_x)O3 (PZT) at the MPB are comparable, at least as
far as the computed values of the piezoelectric coefficient d_15 are concerned.
While our results are generally consistent with experiment, they also suggest
that certain intrinsic properties of BS-PT may be even better than has been
indicated by experiments to date. We also discuss results for PZT that
demonstrate the prominent role played by Pb displacements in its piezoelectric
properties.Comment: 6 pages, with 3 postscript figures embedded. Uses REVTEX and epsf
macros. Also available at
http://www.physics.rutgers.edu/~dhv/preprints/ji_bi/index.htm
Neutrino oscillations with disentanglement of a neutrino from its partners
We bring attention to the fact that in order to understand existing data on
neutrino oscillations, and to design future experiments, it is imperative to
appreciate the role of quantum entanglement. Once this is accounted for, the
resulting energy-momentum conserving phenomenology requires a single new
parameter related to disentanglement of a neutrino from its partners. This
parameter may not be CP symmetric. We illustrate the new ideas, with
potentially measurable effects, in the context of a novel experiment recently
proposed by Gavrin, Gorbachev, Veretenkin, and Cleveland. The strongest impact
of our ideas is on the resolution of various anomalies in neutrino oscillations
and on neutrino propagation in astrophysical environments.Comment: 6 page
Neutrino oscillations and the effect of the finite lifetime of the neutrino source
We consider a neutrino source at rest and discuss a condition for the
existence of neutrino oscillations which derives from the finite lifetime
of the neutrino source particle. This condition is present if the
neutrino source is a free particle such that its wave function is
non-stationary. For a Gaussian wave function and with some simplifying
assumptions, we study the modification of the usual oscillation probability
stemming from . In the present accelerator experiments the effect of
can be neglected. We discuss some experimental situations where the
source lifetime becomes relevant in the oscillation formula.Comment: 13 pages latex file with 2 figure
Statistical Analysis of Different Muon-antineutrino->Electron-antineutrino Searches
A combined statistical analysis of the experimental results of the LSND and
KARMEN \numubnueb oscillation search is presented. LSND has evidence for
neutrino oscillations that is not confirmed by the KARMEN experiment. This
joint analysis is based on the final likelihood results for both data sets. A
frequentist approach is applied to deduce confidence regions. At a combined
confidence level of 36%, there is no area of oscillation parameters compatible
with both experiments. For the complementary confidence of 1-0.36=64%, there
are two well defined regions of oscillation parameters (sin^2(2th),Dm^2)
compatible with both experiments.Comment: 25 pages, including 10 figures, submitted to Phys. Rev.
Cosmological implications of the KATRIN experiment
The upcoming Karlsruhe Tritium Neutrino (KATRIN) experiment will put
unprecedented constraints on the absolute mass of the electron neutrino,
\mnue. In this paper we investigate how this information on \mnue will
affect our constraints on cosmological parameters. We consider two scenarios;
one where \mnue=0 (i.e., no detection by KATRIN), and one where
\mnue=0.3eV. We find that the constraints on \mnue from KATRIN will affect
estimates of some important cosmological parameters significantly. For example,
the significance of and the inferred value of depend
on the results from the KATRIN experiment.Comment: 13 page
Graph-based prediction of missing KPIs through optimization and random forests for KPI systems
Key performance indicators (KPIs) are widely used to monitor and control the production in industry. On an aggregated level, often represented as graphs or interrelated KPI systems, a comprehensive overview is given. However, missing or inaccurate sensor data and KPIs, as well inconsistencies in KPI based management are a major hurdle disturbing operations. To counter the impact of such missing KPIs, we propose a value optimization based approach to reconstruct the values of missing KPIs within a KPI system. While the approach shows successful reconstruction in the case study, the value optimization can be sped up through a random forest prediction of the initial optimization set. Thus, the inclusion of previous knowledge about the system behavior proves beneficial and superior to the pure optimization based approach, as validated by both randomized and simulation-based measurement data
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