-
Double Chooz Collaboration,
Y. Abe,
C. Aberle,
J. C. dos Anjos,
J. C. Barriere,
M. Bergevin,
A. Bernstein,
T. J. C. Bezerra,
L. Bezrukhov,
E. Blucher, [......],
C. Veyssiere,
S. Wagner,
H. Watanabe,
B. White,
C. Wiebusch,
L. Winslow,
M. Worcester,
M. Wurm,
F. Yermia,
V. Zimmer
[show abstract]
[hide abstract]
ABSTRACT: The Double Chooz experiment has determined the value of the neutrino
oscillation parameter $\theta_{13}$ from an analysis of inverse beta decay
interactions with neutron capture on hydrogen. This analysis uses a three times
larger fiducial volume than the standard Double Chooz assessment, which is
restricted to a region doped with gadolinium (Gd), yielding an exposure of
113.1 GW-ton-years. The data sample used in this analysis is distinct from that
of the Gd analysis, and the systematic uncertainties are also largely
independent, with some exceptions, such as the reactor neutrino flux
prediction. A combined rate- and energy-dependent fit finds $\sin^2
2\theta_{13}=0.097\pm 0.034(stat.) \pm 0.034 (syst.)$, excluding the
no-oscillation hypothesis at 2.0 \sigma. This result is consistent with
previous measurements of $\sin^2 2\theta_{13}$.
01/2013;
-
Y. Abe,
C. Aberle,
J. C. dos Anjos,
J. C. Barriere,
M. Bergevin,
A. Bernstein,
T. J. C. Bezerra,
L. Bezrukhov,
E. Blucher, N. S. Bowden, [......],
C. Veyssiere,
S. Wagner,
H. Watanabe,
B. White,
C. Wiebusch,
L. Winslow,
M. Worcester,
M. Wurm,
F. Yermia,
V. Zimmer
[show abstract]
[hide abstract]
ABSTRACT: Double Chooz is unique among modern reactor-based neutrino experiments studying ν̅ e disappearance in that data can be collected with all reactors off. In this paper, we present data from 7.53 days of reactor-off running. Applying the same selection criteria as used in the Double Chooz reactor-on oscillation analysis, a measured background rate of 1.0±0.4 events/day is obtained. The background model for accidentals, cosmogenic β-n-emitting isotopes, fast neutrons from cosmic muons, and stopped-μ decays used in the oscillation analysis is demonstrated to be correct within the uncertainties. Kinematic distributions of the events, which are dominantly cosmic-ray-produced correlated-background events, are provided. The background rates are scaled to the shielding depths of two other reactor-based oscillation experiments, Daya Bay and RENO.
Physical Review D 01/2013; 87(1):011102. · 4.56 Impact Factor
-
Y. Abe,
C. Aberle,
J. C. dos Anjos,
J. C. Barriere,
M. Bergevin,
A. Bernstein,
T. J. C. Bezerra,
L. Bezrukhov,
E. Blucher, N. S. Bowden, [......],
S. Wagner,
H. Watanabe,
B. White,
C. Wiebusch,
L. Winslow,
M. Worcester,
M. Wurm,
F. Yermia,
V. Zimmer,
G. Valdiviesso
[show abstract]
[hide abstract]
ABSTRACT: We present a search for Lorentz violation with 8249 candidate electron antineutrino events taken by the Double Chooz experiment in 227.9 live days of running. This analysis, featuring a search for a sidereal time dependence of the events, is the first test of Lorentz invariance using a reactor-based antineutrino source. No sidereal variation is present in the data and the disappearance results are consistent with sidereal time independent oscillations. Under the Standard-Model Extension, we set the first limits on 14 Lorentz violating coefficients associated with transitions between electron and tau flavor, and set two competitive limits associated with transitions between electron and muon flavor.
Physical Review D 12/2012; 86:112009. · 4.56 Impact Factor
-
Y. Abe,
C. Aberle,
J. C. dos Anjos,
J. C. Barriere,
M. Bergevin,
A. Bernstein,
T. J. C. Bezerra,
L. Bezrukhov,
E. Blucher, N. S. Bowden, [......],
C. Veyssiere,
S. Wagner,
H. Watanabe,
B. White,
C. Wiebusch,
L. Winslow,
M. Worcester,
M. Wurm,
F. Yermia,
V. Zimmer
[show abstract]
[hide abstract]
ABSTRACT: Double Chooz is unique among modern reactor-based neutrino experiments
studying $\bar \nu_e$ disappearance in that data can be collected with all
reactors off. In this paper, we present data from 7.53 days of reactor-off
running. Applying the same selection criteria as used in the Double Chooz
reactor-on oscillation analysis, a measured background rate of 1.0$\pm$0.4
events/day is obtained. The background model for accidentals, cosmogenic
$\beta$-$n$-emitting isotopes, fast neutrons from cosmic muons, and
stopped-$\mu$ decays used in the oscillation analysis is demonstrated to be
correct within the uncertainties. Kinematic distributions of the events, which
are dominantly cosmic-ray-produced correlated-background events, are provided.
The background rates are scaled to the shielding depths of two other
reactor-based oscillation experiments, Daya Bay and RENO.
10/2012;
-
Double Chooz Collaboration,
Y. Abe,
C. Aberle,
J. C. dos Anjos,
M. Bergevin,
A. Bernstein,
T. J. C. Bezerra,
L. Bezrukhov,
E. Blucher, N. S. Bowden, [......],
S. Wagner,
H. Watanabe,
B. White,
C. Wiebusch,
L. Winslow,
M. Worcester,
M. Wurm,
E. Yanovitch,
F. Yermia,
V. Zimmer
[show abstract]
[hide abstract]
ABSTRACT: We present a search for Lorentz violation with 8249 candidate electron
antineutrino events taken by the Double Chooz experiment in 227.9 live days of
running. This analysis, featuring a search for a sidereal time dependence of
the events, is the first test of Lorentz invariance using a reactor-based
antineutrino source. No sidereal variation is present in the data and the
disappearance results are consistent with sidereal time independent
oscillations. Under the Standard-Model Extension (SME), we set the first limits
on fourteen Lorentz violating coefficients associated with transitions between
electron and tau flavor, and set two competitive limits associated with
transitions between electron and muon flavor.
09/2012;
-
Y Abe,
C Aberle,
J C Anjos,
J C Barriere,
M Bergevin,
A Bernstein,
T J C Bezerra,
L Bezrukhov,
E Blucher, N S Bowden, [......],
C Veyssiere,
S Wagner,
H Watanabe,
B White,
C Wiebusch,
L Winslow,
M Worcester,
M Wurm,
F Yermia,
V Zimmer
Phys. Rev. D. 09/2012; 86(5):052008.
-
Y Abe,
C Aberle,
J C Anjos,
J C Barriere,
M Bergevin,
A Bernstein,
T J C Bezerra,
L Bezrukhov,
E Blucher, N S Bowden, [......],
C Veyssiere,
S Wagner,
H Watanabe,
B White,
C Wiebusch,
L Winslow,
M Worcester,
M Wurm,
F Yermia,
V Zimmer
Phys. Rev. D. 09/2012; 86(5):052008.
-
Y. Abe,
C. Aberle,
J. C. dos Anjos,
J. C. Barriere,
M. Bergevin,
A. Bernstein,
T. J. C. Bezerra,
L. Bezrukhov,
E. Blucher, N. S. Bowden, [......],
C. Veyssiere,
S. Wagner,
H. Watanabe,
B. White,
C. Wiebusch,
L. Winslow,
M. Worcester,
M. Wurm,
F. Yermia,
V. Zimmer
[show abstract]
[hide abstract]
ABSTRACT: The Double Chooz experiment has observed 8,249 candidate electron
antineutrino events in 227.93 live days with 33.71 GW-ton-years (reactor power
x detector mass x livetime) exposure using a 10.3 cubic meter fiducial volume
detector located at 1050 m from the reactor cores of the Chooz nuclear power
plant in France. The expectation in case of theta13 = 0 is 8,937 events. The
deficit is interpreted as evidence of electron antineutrino disappearance. From
a rate plus spectral shape analysis we find sin^2 2{\theta}13 = 0.109 \pm
0.030(stat) \pm 0.025(syst). The data exclude the no-oscillation hypothesis at
99.8% CL (2.9{\sigma}).
07/2012;
-
K. N. Abazajian,
M. A. Acero,
S. K. Agarwalla,
A. A. Aguilar-Arevalo,
C. H. Albright,
S. Antusch,
C. A. Arguelles,
A. B. Balantekin,
G. Barenboim,
V. Barger, [......],
W. Winter,
Y. Y. Y. Wong,
T. T. Yanagida,
O. Yasuda,
M. Yeh,
F. Yermia,
Z. W. Yokley,
G. P. Zeller,
L. Zhan,
H. Zhang
[show abstract]
[hide abstract]
ABSTRACT: This white paper addresses the hypothesis of light sterile neutrinos based on
recent anomalies observed in neutrino experiments and the latest astrophysical
data.
04/2012;
-
Y Abe,
C Aberle,
T Akiri,
J C dos Anjos,
F Ardellier,
A F Barbosa,
A Baxter,
M Bergevin,
A Bernstein,
T J C Bezerra, [......],
H Watanabe,
B White,
C Wiebusch,
L Winslow,
M Worcester,
M Wurm,
E Yanovitch,
F Yermia,
K Zbiri,
V Zimmer
[show abstract]
[hide abstract]
ABSTRACT: The Double Chooz experiment presents an indication of reactor electron antineutrino disappearance consistent with neutrino oscillations. An observed-to-predicted ratio of events of 0.944±0.016(stat)±0.040(syst) was obtained in 101 days of running at the Chooz nuclear power plant in France, with two 4.25 GW(th) reactors. The results were obtained from a single 10 m(3) fiducial volume detector located 1050 m from the two reactor cores. The reactor antineutrino flux prediction used the Bugey4 flux measurement after correction for differences in core composition. The deficit can be interpreted as an indication of a nonzero value of the still unmeasured neutrino mixing parameter sin(2)2θ(13). Analyzing both the rate of the prompt positrons and their energy spectrum, we find sin(2)2θ(13)=0.086±0.041(stat)±0.030(syst), or, at 90% C.L., 0.017<sin(2)2θ(13)<0.16.
Physical Review Letters 03/2012; 108(13):131801. · 7.37 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: A wide variety of detection applications exploit the timing correlations that
result from the slowing and eventual capture of neutrons. These include
capture-gated neutron spectrometry, multiple neutron counting for fissile
material detection and identification, and antineutrino detection. There are
several distinct processes that result in correlated signals in these
applications. Depending on the application, one class of correlated events can
be a background that is difficult to distinguish from the class that is of
interest. Furthermore, the correlation timing distribution depends on the
neutron capture agent and detector geometry. Here, we explain the important
characteristics of the neutron capture timing distribution, making reference to
simulations and data from a number of detectors currently in use or under
development. We point out several features that may assist in background
discrimination, and that must be carefully accounted for if accurate detection
efficiencies are to be quoted.
02/2012;
-
Y. Abe,
C. Aberle,
T. Akiri,
J. C. dos Anjos,
F. Ardellier,
A. F. Barbosa,
A. Baxter,
M. Bergevin,
A. Bernstein,
T. J. C. Bezerra, [......],
H. Watanabe,
B. White,
C. Wiebusch,
L. Winslow,
M. Worcester,
M. Wurm,
E. Yanovitch,
F. Yermia,
K. Zbiri,
V. Zimmer
[show abstract]
[hide abstract]
ABSTRACT: The Double Chooz Experiment presents an indication of reactor electron
antineutrino disappearance consistent with neutrino oscillations. A ratio of
0.944 $\pm$ 0.016 (stat) $\pm$ 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$_{th}$ reactors. The results were obtained from a single 10
m$^3$ 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 $\pm$
0.041 (stat) $\pm$ 0.030 (syst), or, at 90% CL, 0.015 $<$ \sang $\ <$ 0.16.
12/2011;
-
[show abstract]
[hide abstract]
ABSTRACT: Fission events from Special Nuclear Material (SNM), such as highly enriched
uranium or plutonium, can produce simultaneous emission of multiple neutrons
and high energy gamma-rays. The observation of time correlations between any of
these particles is a significant indicator of the presence of fissionable
material. Cosmogenic processes can also mimic these types of correlated
signals. However, if the background is sufficiently low and fully
characterized, significant changes in the correlated event rate in the presence
of a target of interest constitutes a robust signature of the presence of SNM.
Since fission emissions are isotropic, adequate sensitivity to these
multiplicities requires a high efficiency detector with a large solid angle
with respect to the target. Water Cerenkov detectors are a cost-effective
choice when large solid angle coverage is required. In order to characterize
the neutron detection performance of large-scale water Cerenkov detectors, we
have designed and built a 3.5 kL water Cerenkov-based gamma-ray and neutron
detector, and modeled the detector response in Geant4 [1]. We report the
position-dependent neutron detection efficiency and energy response of the
detector, as well as the basic characteristics of the simulation.
05/2011;
-
C E Aalseth,
P S Barbeau, N S Bowden,
B Cabrera-Palmer,
J Colaresi,
J I Collar,
S Dazeley,
P de Lurgio,
J E Fast,
N Fields, [......],
M G Marino,
H S Miley,
M L Miller,
J L Orrell,
D C Radford,
D Reyna,
O Tench,
T D Van Wechel,
J F Wilkerson,
K M Yocum
[show abstract]
[hide abstract]
ABSTRACT: We report on several features in the energy spectrum from an ultralow-noise germanium detector operated deep underground. By implementing a new technique able to reject surface events, a number of cosmogenic peaks can be observed for the first time. We discuss an irreducible excess of bulklike events below 3 keV in ionization energy. These could be caused by unknown backgrounds, but also dark matter interactions consistent with DAMA/LIBRA. It is not yet possible to determine their origin. Improved constraints are placed on a cosmological origin for the DAMA/LIBRA effect.
Physical Review Letters 04/2011; 106(13):131301. · 7.37 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Measurement of the three dimensional trajectory and specific ionization of recoil protons using a hydrogen gas time projection chamber provides directional information about incident fast neutrons. Here we demonstrate directional fast neutron detection using such a device. The wide field of view and excellent gamma rejection that are obtained suggest that this device is well suited to searches for special nuclear materials, among other applications.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. 10/2010;
-
C. E. Aalseth,
P. S. Barbeau, N. S. Bowden,
B. Cabrera-Palmer,
J. Colaresi,
J. I. Collar,
S. Dazeley,
P. de Lurgio,
G. Drake,
J. E. Fast, [......],
M L Miller,
J. L. Orrell,
D. C. Radford,
D. Reyna,
R. G. H. Robertson,
R L Talaga,
O. Tench,
T. D. Van Wechel,
J. F. Wilkerson,
K. M. Yocum
[show abstract]
[hide abstract]
ABSTRACT: We report on several features present in the energy spectrum from an ultra
low-noise germanium detector operated at 2,100 m.w.e. By implementing a new
technique able to reject surface events, a number of cosmogenic peaks can be
observed for the first time. We discuss several possible causes for an
irreducible excess of bulk-like events below 3 keVee, including a dark matter
candidate common to the DAMA/LIBRA annual modulation effect, the hint of a
signal in CDMS, and phenomenological predictions. Improved constraints are
placed on a cosmological origin for the DAMA/LIBRA effect.
02/2010;
-
[show abstract]
[hide abstract]
ABSTRACT: Organic scintillators are widely used for fast neutron detection and spectroscopy. Several effects complicate the interpretation of results from detectors based upon these materials. First, fast neutrons will often leave a detector before depositing all of their energy within it. Second, fast neutrons will typically scatter several times within a detector, and there is a non-proportional relationship between the energy of, and the scintillation light produced by, each individual scatter; therefore, there is not a deterministic relationship between the scintillation light observed and the neutron energy deposited. Here we demonstrate a hardware technique for reducing both of these effects. Use of a segmented detector allows for the event-by-event correction of the light yield non-proportionality and for the preferential selection of events with near-complete energy deposition, since these will typically have high segment multiplicities. Comment: Accepted for publication in Nuclear Instruments and Methods in Physics Research Section A
08/2009;
-
I. Jovanovic,
M. Heffner,
L. Rosenberg, N.S. Bowden,
A. Bernstein,
D. Carter,
M. Foxe,
M. Hotz,
M. Howe,
A. Myers,
C. Winant
[show abstract]
[hide abstract]
ABSTRACT: Time projection chambers offer unique capabilities for detection of fast neutrons from special nuclear material. We have demonstrated a directional detector for fast neutrons based on a hydrogen-filled time projection chamber. Experimental results for imaging of a fissile material surrogate <sup>252</sup>Cf source are presented. Strategies for background rejection via particle identification are discussed.
IEEE Transactions on Nuclear Science 07/2009; · 1.45 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: By operating an antineutrino detector of simple design during several fuel cycles, we observed long term changes in antineutrino flux that result from the isotopic evolution of a commercial pressurized water reactor. Measurements made with simple antineutrino detectors of this kind offer an alternative means for verifying fissile inventories at reactors, as part of International Atomic Energy Agency and other reactor safeguards regimes.
Journal of Applied Physics 04/2009; · 2.17 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: We will describe an assembly of radiation detectors that quantifies the gamma, muon, and fast and thermal neutron fluxes present at potential above ground antineutrino detector sites. Antineutrino detectors show great promise for reactor safeguards applications, due to their ability to monitor thermal power and/or fissile content. One of the major technical challenges that this safeguard application faces is the ability to distinguish signals from antineutrinos originating in a reactor core from noise due to background created by terrestrial and cosmogenic radiation. To date, antineutrino experiments have increased the signal to noise in their detectors by surrounding the experiments with significant shielding and placing them underground. For the safeguards agency, this is less than optimal, as it increases the overall size of the device and limits the range of possible deployment locations. Placing reactor monitoring antineutrino detectors at, or near, the surface would greatly increase the range of possible deployment locations. In order to investigate designs that would allow this, we must understand the backgrounds found above ground that can mimic the antineutrino signal so that these can be easily identified, separated, and subtracted rather than shielded. The design, construction, calibration, and results from the deployment of this background measurement system at a variety of sites will be presented.
Journal of Physics Conference Series 11/2008; 136(4):042003.
