74 research outputs found
Double-Chooz: a search for Theta13
The Double-Chooz experiment goal is to search for a non-vanishing value of
the Theta13 neutrino mixing angle. This is the last step to accomplish prior
moving towards a new era of precision measurements in the lepton sector. The
current best constraint on the third mixing angle comes from the CHOOZ reactor
neutrino experiment (90% C.L., eV). Double-Chooz will explore the range of
from 0.2 to 0.03-0.02, within three years of data
taking. The improvement of the CHOOZ result requires an increase in the
statistics, a reduction of the systematic error below one percent, and a
careful control of the backgrounds. Therefore, Double-Chooz will use two
identical detectors, one at 150 m and another at 1.05 km distance from the
Chooz nuclear cores. In addition, we will to use the near detector as a ``state
of the art'' prototype to investigate the potential of neutrinos for monitoring
the civil nuclear power plants. The plan is to start operation with two
detectors in 2008, and to reach a sensitivity sin of 0.05
in 2009, and 0.03-0.02 in 2011.Comment: 3 pages, 1 figure, Proceedings of Nufact'04, July 26 - August 01
2004, Osak
The Reactor Antineutrino Anomaly
Recently new reactor antineutrino spectra have been provided for 235U, 239Pu,
241Pu and 238U, increasing the mean flux by about 3 percent. To good
approximation, this reevaluation applies to all reactor neutrino experiments.
The synthesis of published experiments at reactor-detector distances <100 m
leads to a ratio of observed event rate to predicted rate of 0.976(0.024). With
our new flux evaluation, this ratio shifts to 0.943(0.023), leading to a
deviation from unity at 98.6% C.L. which we call the reactor antineutrino
anomaly. The compatibility of our results with the existence of a fourth
non-standard neutrino state driving neutrino oscillations at short distances is
discussed. The combined analysis of reactor data, gallium solar neutrino
calibration experiments, and MiniBooNE-neutrino data disfavors the
no-oscillation hypothesis at 99.8% C.L. The oscillation parameters are such
that |Delta m_{new}^2|>1.5 eV^2 (95%) and sin^2(2\theta_{new})=0.14(0.08)
(95%). Constraints on the theta13 neutrino mixing angle are revised.Comment: 19 pages, 15 figures ; v2/3 include typos corrected ; v4 final
version: add 5 Rovno & 2 Savannah River results + add additional constistency
checks + add a discussion on the inverse beta decay cross section
normlizatio
On the origin of the reactor antineutrino anomalies in light of a new summation model with parameterized transitions
We investigate the possible origins of the norm and shape reactor
antineutrino anomalies in the framework of a summation model (SM) where
transitions are simulated by a phenomenological Gamow-Teller
-decay strength model. The general trends of the discrepancies to the
Huber-Mueller model on the antineutrino side can be reproduced both in norm and
shape. From the exact electron-antineutrino correspondence of the SM model, we
predict similar distortions in the electron spectra, suggesting that biases on
the reference fission-electron spectra could be at the origin of the anomalies
Chasing with new reactor neutrino experiments
It is now widely accepted that a new middle baseline disappearance reactor
neutrino experiment with multiple detectors could provide a clean measurement
of the mixing angle, free from any parameter degeneracies and
correlations induced by matter effect and the unknown leptonic Dirac CP phase.
The current best constraint on the third mixing angle comes from the Chooz
reactor neutrino experiment (90 C.L., eV). Several projects of experiment, with
different timescales, have been proposed over the last two years all around the
world. Their sensitivities range from 0.01 to 0.03,
having thus an excellent discovery potential of the fraction of
.Comment: Talk given at the 6th International Workshop on Neutrino Factories &
Superbeams, July 26-Aug 1, 2004, Osaka, Japan. 5 page
Prototype scintillator cell for an In-based solar neutrino detector
We describe the work carried out at MPIK to design, model, build and
characterize a prototype cell filled with a novel indium-loaded scintillator of
interest for real-time low energy solar neutrino spectroscopy. First, light
propagation in optical modules was studied with experiments and Monte Carlo
simulations. Subsequently a 5 cm x 5 cm x 100 cm prototype detector was set up
and the optical performances of several samples were measured. We first tested
a benchmark PXE-based scintillator, which performed an attenuation length of ~
4.2 m and a photo-electron yield of ~ 730 pe/MeV. Then we measured three
In-loaded samples. At an In-loading of 44 g/l, an energy resolution of ~ 11.6 %
and a spatial resolution of ~ 7 cm were attained for 477 keV recoil electrons.
The long-range attenuation length in the cell was ~1.3 m and the estimated
photo-electron yield ~ 200 pe/MeV. Light attenuation and relative light output
of all tested samples could be reproduced reasonably well by MC. All optical
properties of this system have remained stable over a period of > 1 y.Comment: 57 pages, 19 figures, 10 tables elsevier template for manuscript
submission submitted to NIMA 10 February 200
Online Monitoring of the Osiris Reactor with the Nucifer Neutrino Detector
Originally designed as a new nuclear reactor monitoring device, the Nucifer
detector has successfully detected its first neutrinos. We provide the second
shortest baseline measurement of the reactor neutrino flux. The detection of
electron antineutrinos emitted in the decay chains of the fission products,
combined with reactor core simulations, provides an new tool to assess both the
thermal power and the fissile content of the whole nuclear core and could be
used by the Inter- national Agency for Atomic Energy (IAEA) to enhance the
Safeguards of civil nuclear reactors. Deployed at only 7.2m away from the
compact Osiris research reactor core (70MW) operating at the Saclay research
centre of the French Alternative Energies and Atomic Energy Commission (CEA),
the experiment also exhibits a well-suited configuration to search for a new
short baseline oscillation. We report the first results of the Nucifer
experiment, describing the performances of the 0.85m3 detector remotely
operating at a shallow depth equivalent to 12m of water and under intense
background radiation conditions. Based on 145 (106) days of data with reactor
ON (OFF), leading to the detection of an estimated 40760 electron
antineutrinos, the mean number of detected antineutrinos is 281 +- 7(stat) +-
18(syst) electron antineutrinos/day, in agreement with the prediction 277(23)
electron antineutrinos/day. Due the the large background no conclusive results
on the existence of light sterile neutrinos could be derived, however. As a
first societal application we quantify how antineutrinos could be used for the
Plutonium Management and Disposition Agreement.Comment: 22 pages, 16 figures - Version
Light Sterile Neutrinos: A White Paper
This white paper addresses the hypothesis of light sterile neutrinos based on
recent anomalies observed in neutrino experiments and the latest astrophysical
data
Indication for the disappearance of reactor electron antineutrinos in the Double Chooz experiment
The Double Chooz Experiment presents an indication of reactor electron
antineutrino disappearance consistent with neutrino oscillations. A ratio of
0.944 0.016 (stat) 0.040 (syst) observed to predicted events was
obtained in 101 days of running at the Chooz Nuclear Power Plant in France,
with two 4.25 GW reactors. The results were obtained from a single 10
m fiducial volume detector located 1050 m from the two reactor cores. The
reactor antineutrino flux prediction used the Bugey4 measurement as an anchor
point. The deficit can be interpreted as an indication of a non-zero value of
the still unmeasured neutrino mixing parameter \sang. Analyzing both the rate
of the prompt positrons and their energy spectrum we find \sang = 0.086
0.041 (stat) 0.030 (syst), or, at 90% CL, 0.015 \sang 0.16.Comment: 7 pages, 4 figures, (new version after PRL referee's comments
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