397 research outputs found
Status and perspectives of short baseline studies
The study of flavor changing neutrinos is a very active field of research. I
will discuss the status of ongoing and near term experiments investigating
neutrino properties at short distances from the source. In the next few years,
the Double Chooz, RENO and Daya Bay reactor neutrino experiments will start
looking for signatures of a non-zero value of the mixing angle
with much improved sensitivities. The MiniBooNE experiment is investigating the
LSND anomaly by looking at both the and
appearance channels. Recent results on
cross section measurements will be discussed briefly.Comment: 6 pages, 2 figures, to appear in the proceedings of the 11th
International Conference on Topics in Astroparticle and Underground Physics
(TAUP 2009), Rome, Italy, 1-5 July 200
Results from the first use of low radioactivity argon in a dark matter search
Liquid argon is a bright scintillator with potent particle identification
properties, making it an attractive target for direct-detection dark matter
searches. The DarkSide-50 dark matter search here reports the first WIMP search
results obtained using a target of low-radioactivity argon. DarkSide-50 is a
dark matter detector, using two-phase liquid argon time projection chamber,
located at the Laboratori Nazionali del Gran Sasso. The underground argon is
shown to contain Ar-39 at a level reduced by a factor (1.4 +- 0.2) x 10^3
relative to atmospheric argon. We report a background-free null result from
(2616 +- 43) kg d of data, accumulated over 70.9 live-days. When combined with
our previous search using an atmospheric argon, the 90 % C.L. upper limit on
the WIMP-nucleon spin-independent cross section based on zero events found in
the WIMP search regions, is 2.0 x 10^-44 cm^2 (8.6 x 10^-44 cm^2, 8.0 x 10^-43
cm^2) for a WIMP mass of 100 GeV/c^2 (1 TeV/c^2 , 10 TeV/c^2).Comment: Accepted by Phys. Rev.
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
Final Measurement of the U235 Antineutrino Energy Spectrum with the PROSPECT-I Detector at HFIR
This Letter reports one of the most precise measurements to date of the
antineutrino spectrum from a purely U235-fueled reactor, made with the final
dataset from the PROSPECT-I detector at the High Flux Isotope Reactor. By
extracting information from previously unused detector segments, this analysis
effectively doubles the statistics of the previous PROSPECT measurement. The
reconstructed energy spectrum is unfolded into antineutrino energy and compared
with both the Huber-Mueller model and a spectrum from a commercial reactor
burning multiple fuel isotopes. A local excess over the model is observed in
the 5MeV to 7MeV energy region. Comparison of the PROSPECT results with those
from commercial reactors provides new constraints on the origin of this excess,
disfavoring at 2.2 and 3.2 standard deviations the hypotheses that
antineutrinos from U235 are solely responsible and non-contributors to the
excess observed at commercial reactors respectively.Comment: The paper has been updated with an improved parametrization of the
observed antineutrino spectrum excess and extended discussion on its
potential isotopic origi
Calibration strategy of the PROSPECT-II detector with external and intrinsic sources
This paper presents an energy calibration scheme for an upgraded reactor
antineutrino detector for the Precision Reactor Oscillation and Spectrum
Experiment (PROSPECT). The PROSPECT collaboration is preparing an upgraded
detector, PROSPECT-II (P-II), to advance capabilities for the investigation of
fundamental neutrino physics, fission processes and associated reactor neutrino
flux, and nuclear security applications. P-II will expand the statistical power
of the original PROSPECT (P-I) dataset by at least an order of magnitude. The
new design builds upon previous P-I design and focuses on improving the
detector robustness and long-term stability to enable multi-year operation at
one or more sites. The new design optimizes the fiducial volume by elimination
of dead space previously occupied by internal calibration channels, which in
turn necessitates the external deployment. In this paper, we describe a
calibration strategy for P-II. The expected performance of externally deployed
calibration sources is evaluated using P-I data and a well-benchmarked
simulation package by varying detector segmentation configurations in the
analysis. The proposed external calibration scheme delivers a compatible energy
scale model and achieves comparable performance with the inclusion of an
additional AmBe neutron source, in comparison to the previous internal
arrangement. Most importantly, the estimated uncertainty contribution from the
external energy scale calibration model meets the precision requirements of the
P-II experiment.Comment: 19 pages, 10 figure
Long-Baseline Neutrino Facility (LBNF) and Deep Underground Neutrino Experiment (DUNE) Conceptual Design Report Volume 2: The Physics Program for DUNE at LBNF
The Physics Program for the Deep Underground Neutrino Experiment (DUNE) at
the Fermilab Long-Baseline Neutrino Facility (LBNF) is described
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