543 research outputs found
Earth Matter Effects at Very Long Baselines and the Neutrino Mass Hierarchy
We study matter effects which arise in the muon neutrino oscillation and
survival probabilities relevant to atmospheric neutrino and very long baseline
beam experiments. The inter-relations between the three probabilities P_{\mu
e}, P_{\mu \tau} and P_{\mu \mu} are examined. It is shown that large and
observable sensitivity to the neutrino mass hierarchy can be present in P_{\mu
\mu} and P_{\mu \tau}. We emphasize that at baselines of > 7000 Km, matter
effects in P_{\mu \tau} can be large under certain conditions. The muon
survival rates in experiments with very long baselines thus depend on matter
effects in both P_{\mu \tau} and P_{\mu e}. We indicate where these effects are
sensitive to \theta_{13}, and identify ranges of E and L where the event rates
increase with decreasing \theta_{13}, providing a handle to probe small
\theta_{13}. The effect of parameter degeneracies in the three probabilities at
these baselines and energies is studied in detail. Realistic event rate
calculations are performed for a charge discriminating 100 kT iron calorimeter
which demonstrate the possibility of realising the goal of determining the
neutrino mass hierarchy using atmospheric neutrinos. It is shown that a careful
selection of energy and baseline ranges is necessary in order to obtain a
statistically significant signal, and that the effects are largest in bins
where matter effects in both P_{\mu e} and P_{\mu \tau} combine constructively.
Under these conditions, upto a 4\sigma signal for matter effects is possible
(for \Delta_{31}>0) within a timescale appreciably shorter than the one
anticipated for neutrino factories.Comment: 40 pages, 27 figures, version to match the published versio
A simple model of reactor cores for reactor neutrino flux calculations for the KamLAND experiment
KamLAND is a reactor neutrino oscillation experiment with a very long
baseline. This experiment successfully measured oscillation phenomena of
reactor antineutrinos coming mainly from 53 reactors in Japan. In order to
extract the results, it is necessary to accurately calculate time-dependent
antineutrino spectra from all the reactors. A simple model of reactor cores and
code implementing it were developed for this purpose. This paper describes the
model of the reactor cores used in the KamLAND reactor analysis.Comment: 14 pages, 7 figures, submitted to Nuclear Instruments and Methods in
Physics Research
Reactor monitoring and safeguards using antineutrino detectors
Nuclear reactors have served as the antineutrino source for many fundamental
physics experiments. The techniques developed by these experiments make it
possible to use these very weakly interacting particles for a practical
purpose. The large flux of antineutrinos that leaves a reactor carries
information about two quantities of interest for safeguards: the reactor power
and fissile inventory. Measurements made with antineutrino detectors could
therefore offer an alternative means for verifying the power history and
fissile inventory of a reactors, as part of International Atomic Energy Agency
(IAEA) and other reactor safeguards regimes. Several efforts to develop this
monitoring technique are underway across the globe.Comment: 6 pages, 4 figures, Proceedings of XXIII International Conference on
Neutrino Physics and Astrophysics (Neutrino 2008); v2: minor additions to
reference
Production and optical properties of liquid scintillator for the JSNS experiment
The JSNS (J-PARC Sterile Neutrino Search at J-PARC Spallation Neutron
Source) experiment will search for neutrino oscillations over a 24 m short
baseline at J-PARC. The JSNS inner detector will be filled with 17 tons
of gadolinium-loaded liquid scintillator (LS) with an additional 31 tons of
unloaded LS in the intermediate -catcher and outer veto volumes.
JSNS has chosen Linear Alkyl Benzene (LAB) as an organic solvent because
of its chemical properties. The unloaded LS was produced at a refurbished
facility, originally used for scintillator production by the RENO experiment.
JSNS plans to use ISO tanks for the storage and transportation of the LS.
In this paper, we describe the LS production, and present measurements of its
optical properties and long term stability. Our measurements show that storing
the LS in ISO tanks does not result in degradation of its optical properties.Comment: 7 pages, 4 figures
Comparison of residual oil cluster size distribution, morphology and saturation in oil-wet and water-wet sandstone
We imaged an oil-wet sandstone at residual oil saturation (Sor) conditions using X-ray micro-tomography with a nominal voxel size of (9 μm)3 and monochromatic light from a synchrotron source. The sandstone was rendered oil-wet by ageing with a North Sea crude oil to represent a typical wettability encountered in hydrocarbon reservoirs. We measured a significantly lower Sor for the oil-wet core (18.8%) than for an analogue water-wet core (35%). We analysed the residual oil cluster size distribution and find consistency with percolation theory that predicts a power-law cluster size distribution. We measure a power-law exponent τ = 2.12 for the oil-wet core which is higher than τ for the water-wet system (τ = 2.05), indicating fewer large clusters in the oil-wet case. The clusters are rough and sheet-like consistent with connectivity established through layers in the pore space and occupancy of the smaller pores; in contrast the clusters for water-wet media occupy the centres of the larger pores. These results imply less trapping of oil, but with a greater surface area for dissolution. In carbon storage applications, this suggests that in CO2-wet systems, capillary trapping is less significant, but that there is a large surface area for dissolution and reaction
White paper: CeLAND - Investigation of the reactor antineutrino anomaly with an intense 144Ce-144Pr antineutrino source in KamLAND
We propose to test for short baseline neutrino oscillations, implied by the
recent reevaluation of the reactor antineutrino flux and by anomalous results
from the gallium solar neutrino detectors. The test will consist of producing a
75 kCi 144Ce - 144Pr antineutrino source to be deployed in the Kamioka Liquid
Scintillator Anti-Neutrino Detector (KamLAND). KamLAND's 13m diameter target
volume provides a suitable environment to measure energy and position
dependence of the detected neutrino flux. A characteristic oscillation pattern
would be visible for a baseline of about 10 m or less, providing a very clean
signal of neutrino disappearance into a yet-unknown, "sterile" state. Such a
measurement will be free of any reactor-related uncertainties. After 1.5 years
of data taking the Reactor Antineutrino Anomaly parameter space will be tested
at > 95% C.L.Comment: White paper prepared for Snowmass-2013; slightly different author
lis
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