536 research outputs found
Systematic limits on sin^2{2theta_{13}} in neutrino oscillation experiments with multi-reactors
Sensitivities to sin^2{2theta_{13}} without statistical errors (``systematic
limit'') are investigated in neutrino oscillation experiments with multiple
reactors. Using an analytical approach, we show that the systematic limit on
sin^2{2theta_{13}} is dominated by the uncorrelated systematic error sigma_u of
the detector. Even in an experiment with multi-detectors and multi-reactors, it
turns out that most of the systematic errors including the one due to the
nature of multiple sources is canceled as in the case with a single reactor
plus two detectors, if the near detectors are placed suitably. The case of the
KASKA plan (7 reactors and 3 detectors) is investigated in detail, and it is
explicitly shown that it does not suffer from the extra uncertainty due to
multiple reactors.Comment: 26 pages, 10 eps-files, revtex
Reactor Measurement of and Its Complementarity to Long-Baseline Experiments
A possibility to measure using reactor neutrinos is
examined in detail. It is shown that the sensitivity
can be reached with 20 ton-year data by placing identical CHOOZ-like detectors
at near and far distances from a giant nuclear power plant whose total thermal
energy is 24.3 . It is emphasized that this
measurement is free from the parameter degeneracies which occur in accelerator
appearance experiments, and therefore the reactor measurement plays a role
complementary to accelerator experiments. It is also shown that the reactor
measurement may be able to resolve the degeneracy in if
and are relatively large.Comment: 25 pages, 8 figures, uses revtex4 and graphicx. Several modifications
added to make the text easier to understand. Two more figures added. To be
published in Phys. Rev.
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
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
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
On-site underground background measurements for the KASKA reactor-neutrino experiment
On-site underground background measurements were performed for the planned
reactor-neutrino oscillation experiment KASKA at Kashiwazaki-Kariwa nuclear
power station in Niigata, Japan. A small-diameter boring hole was excavated
down to 70m underground level, and a detector unit for -ray and
cosmic-muon measurements was placed at various depths to take data. The data
were analyzed to obtain abundance of natural radioactive elements in the
surrounding soil and rates of cosmic muons that penetrate the overburden. The
results will be reflected in the design of the KASKA experiment.Comment: 9 pages, 7 figures, final version for publication. Table 1 and Fig.5
have change
Systematic limits on sin22theta13 in neutrino oscillation experiments with multireactors
Sensitivities to sin22theta13 without statistical errors ("systematic limit") are investigated in neutrino oscillation experiments with multiple reactors. Using an analytical approach, we show that the systematic limit on sin22theta13 is dominated by the uncorrelated systematic error sigmau of the detector. Even in an experiment with multidetectors and multireactors, it turns out that most of the systematic errors including the one due to the nature of multiple sources is canceled as in the case with a single reactor plus two detectors, if the near detectors are placed suitably. The case of the KASKA plan (7 reactors and 3 detectors) is investigated in detail, and it is explicitly shown that it does not suffer from the extra uncertainty due to multiple reactors
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