-
K. Abe,
N. Abgrall,
H. Aihara,
T. Akiri,
J. B. Albert,
C. Andreopoulos,
S. Aoki,
A. Ariga,
T. Ariga,
S. Assylbekov, [......],
N. Yershov,
M. Yokoyama,
Ì T. Yuan,
A. Zalewska,
L. Zambelli,
K. Zaremba,
M. Ziembicki,
E. D. Zimmerman,
M. Zito,
and J. Zmuda
[show abstract]
[hide abstract]
ABSTRACT: T2K has performed the first measurement of \nu{\mu} inclusive charged current
interactions on carbon at neutrino energies of ~1 GeV where the measurement is
reported as a flux-averaged double differential cross section in muon momentum
and angle. The flux is predicted by the beam Monte Carlo and external data,
including the results from the NA61/SHINE experiment. The data used for this
measurement were taken in 2010 and 2011, with a total of 10.8 x 10^{19}
protons-on-target. The analysis is performed on 4485 inclusive charged current
interaction candidates selected in the most upstream fine-grained scintillator
detector of the near detector.
The flux-averaged total cross section is <\sigma_CC>_\phi =(6.91 +/- 0.13
(stat) +/- 0.84 (syst)) x10^{-39} cm^2/nucleon for a mean neutrino energy of
0.85 GeV.
02/2013;
-
Collaboration,
K. Abe,
N. Abgrall,
H. Aihara,
T. Akiri,
J. B. Albert,
C. Andreopoulos,
S. Aoki,
A. Ariga,
T. Ariga, [......],
N. Yershov,
M. Yokoyama,
T. Yuan,
A. Zalewska,
L. Zambelli,
K. Zaremba,
M. Ziembicki,
E. D. Zimmerman,
M. Zito,
J. Zmuda
[show abstract]
[hide abstract]
ABSTRACT: The Tokai-to-Kamioka (T2K) experiment studies neutrino oscillations using an
off-axis muon neutrino beam with a peak energy of about 0.6 GeV that originates
at the J-PARC accelerator facility. Interactions of the neutrinos are observed
at near detectors placed at 280 m from the production target and at the far
detector -- Super-Kamiokande (SK) -- located 295 km away. The flux prediction
is an essential part of the successful prediction of neutrino interaction rates
at the T2K detectors and is an important input to T2K neutrino oscillation and
cross section measurements. A FLUKA and GEANT3 based simulation models the
physical processes involved in the neutrino production, from the interaction of
primary beam protons in the T2K target, to the decay of hadrons and muons that
produce neutrinos. The simulation uses proton beam monitor measurements as
inputs. The modeling of hadronic interactions is re-weighted using thin target
hadron production data, including recent charged pion and kaon measurements
from the NA61/SHINE experiment. For the first T2K analyses the uncertainties on
the flux prediction are evaluated to be below 15% near the flux peak. The
uncertainty on the ratio of the flux predictions at the far and near detectors
is less than 2% near the flux peak.
11/2012;
-
A. Gando,
Y. Gando,
K. Ichimura,
H. Ikeda,
K. Inoue,
Y. Kibe,
Y. Kishimoto,
M. Koga,
Y. Minekawa,
T. Mitsui, [......],
K. E. Downum,
G. Gratta,
Y. Efremenko,
Y. Kamyshkov,
O. Perevozchikov,
H. J. Karwowski,
D. M. Markoff,
W. Tornow,
K. M. Heeger,
and M. P. Decowski
[show abstract]
[hide abstract]
ABSTRACT: We present the results of a search for extraterrestrial electron antineutrinos ('s) in the energy range using the KamLAND detector. In an exposure of 4.53 kton-year, we identify 25 candidate events. All of the candidate events can be attributed to background, most importantly neutral current atmospheric neutrino interactions, setting an upper limit on the probability of 8B solar ν e 's converting into 's at 5.3 × 10–5 (90% CL), if we assume an undistorted shape. This limit corresponds to a solar flux of 93 cm–2 s–1 or an event rate of 1.6 events (kton – year)–1 above the energy threshold . The present data also allows us to set more stringent limits on the diffuse supernova neutrino flux and on the annihilation rates for light dark matter particles.
The Astrophysical Journal 01/2012; 745(2):193. · 6.02 Impact Factor
-
Collaboration,
K. Abe,
N. Abgrall,
Y. Ajima,
H. Aihara,
J. B. Albert,
C. Andreopoulos,
B. Andrieu,
M. D. Anerella,
S. Aoki, [......],
M. Yokoyama,
T. Yuan,
A. Zalewska,
J. Zalipska,
L. Zambelli,
K. Zaremba,
M. Ziembicki,
E. D. Zimmerman,
M. Zito,
J. Zmuda
[show abstract]
[hide abstract]
ABSTRACT: We report a measurement of muon-neutrino disappearance in the T2K experiment.
The 295-km muon-neutrino beam from Tokai to Kamioka is the first implementation
of the off-axis technique in a long-baseline neutrino oscillation experiment.
With data corresponding to 1.43 10**20 protons on target, we observe 31
fully-contained single muon-like ring events in Super-Kamiokande, compared with
an expectation of 104 +- 14 (syst) events without neutrino oscillations. The
best-fit point for two-flavor nu_mu -> nu_tau oscillations is sin**2(2
theta_23) = 0.98 and |\Delta m**2_32| = 2.65 10**-3 eV**2. The boundary of the
90 % confidence region includes the points (sin**2(2 theta_23),|\Delta
m**2_32|) = (1.0, 3.1 10**-3 eV**2), (0.84, 2.65 10**-3 eV**2) and (1.0, 2.2
10**-3 eV**2).
01/2012;
-
S. Assylbekov, B. E. Berger,
H. Berns,
D. Beznosko,
A. Bodek,
R. Bradford,
N. Buchanan,
H. Budd,
Y. Caffari,
K. Connolly, [......],
A. S. Tadepalli,
I. J. Taylor,
W. Toki,
C. Vanek,
D. Warner,
A. Weber,
R. J. Wilkes,
R. J. Wilson,
C. Yanagisawa,
T. Yuan
[show abstract]
[hide abstract]
ABSTRACT: The Pi-Zero detector (P{\O}D) is one of the subdetectors that makes up the
off-axis near detector for the Tokai-to-Kamioka (T2K) long baseline neutrino
experiment. The primary goal for the P{\O}D is to measure the relevant cross
sections for neutrino interactions that generate pi-zero's, especially the
cross section for neutral current pi-zero interactions, which are one of the
dominant sources of background to the electron neutrino appearance signal in
T2K. The P{\O}D is composed of layers of plastic scintillator alternating with
water bags and brass sheets or lead sheets and is one of the first detectors to
use Multi-Pixel Photon Counters (MPPCs) on a large scale.
11/2011;
-
K Abe,
N. Abgrall,
Y. Ajima,
H. Aihara,
J. B. Albert,
C. Andreopoulos,
B Andrieu,
M. D. Anerella,
S Aoki,
O. Araoka, [......],
M Yokoyama,
T Yuan,
A Zalewska,
J. Zalipska,
L. Zambelli,
K Zaremba,
M Ziembicki,
E. D. Zimmerman,
M Zito,
J. Zmuda
[show abstract]
[hide abstract]
ABSTRACT: Precise measurement of neutrino beam direction and intensity was achieved
based on a new concept with modularized neutrino detectors. INGRID (Interactive
Neutrino GRID) is an on-axis near detector for the T2K long baseline neutrino
oscillation experiment. INGRID consists of 16 identical modules arranged in
horizontal and vertical arrays around the beam center. The module has a
sandwich structure of iron target plates and scintillator trackers. INGRID
directly monitors the muon neutrino beam profile center and intensity using the
number of observed neutrino events in each module. The neutrino beam direction
is measured with accuracy better than 0.4 mrad from the measured profile
center. The normalized event rate is measured with 4% precision.
11/2011;
-
Kamland Collaboration,
A. Gando,
Y. Gando,
K. Ichimura,
H. Ikeda,
K. Inoue,
Y. Kibe,
Y. Kishimoto,
M. Koga,
Y. Minekawa, [......],
K. E. Downum,
G. Gratta,
K. Tolich,
Y. Efremenko,
O. Perevozchikov,
H. J. Karwowski,
D. M. Markoff,
W. Tornow,
K. M. Heeger,
M. P. Decowski
[show abstract]
[hide abstract]
ABSTRACT: The Earth has cooled since its formation, yet the decay of radiogenic
isotopes, and in particular uranium, thorium and potassium, in the
planet's interior provides a continuing heat source. The current total
heat flux from the Earth to space is 44.2+/-1.0TW, but the relative
contributions from residual primordial heat and radiogenic decay remain
uncertain. However, radiogenic decay can be estimated from the flux of
geoneutrinos, electrically neutral particles that are emitted during
radioactive decay and can pass through the Earth virtually unaffected.
Here we combine precise measurements of the geoneutrino flux from the
Kamioka Liquid-Scintillator Antineutrino Detector, Japan, with existing
measurements from the Borexino detector, Italy. We find that decay of
uranium-238 and thorium-232 together contribute TW to Earth's heat flux.
The neutrinos emitted from the decay of potassium-40 are below the
limits of detection in our experiments, but are known to contribute 4TW.
Taken together, our observations indicate that heat from radioactive
decay contributes about half of Earth's total heat flux. We therefore
conclude that Earth's primordial heat supply has not yet been exhausted.
Nature Geoscience 08/2011; 4:647-651. · 11.75 Impact Factor
-
K Abe,
N Abgrall,
Y Ajima,
H Aihara,
J B Albert,
C Andreopoulos,
B Andrieu,
S Aoki,
O Araoka,
J Argyriades, [......],
N Yershov,
M Yokoyama,
A Zalewska,
J Zalipska,
L Zambelli,
K Zaremba,
M Ziembicki,
E D Zimmerman,
M Zito,
J Żmuda
[show abstract]
[hide abstract]
ABSTRACT: The T2K experiment observes indications of ν(μ) → ν(e) appearance in data accumulated with 1.43×10(20) protons on target. Six events pass all selection criteria at the far detector. In a three-flavor neutrino oscillation scenario with |Δm(23)(2)| = 2.4×10(-3) eV(2), sin(2)2θ(23) = 1 and sin(2)2θ(13) = 0, the expected number of such events is 1.5±0.3(syst). Under this hypothesis, the probability to observe six or more candidate events is 7×10(-3), equivalent to 2.5σ significance. At 90% C.L., the data are consistent with 0.03(0.04) < sin(2)2θ(13) < 0.28(0.34) for δ(CP) = 0 and a normal (inverted) hierarchy.
Physical Review Letters 07/2011; 107(4):041801. · 7.37 Impact Factor
-
Collaboration,
N. Abgrall,
H. Aihara,
Y. Ajima,
J. B. Albert,
D. Allan,
P. -A. Amaudruz,
C. Andreopoulos,
B. Andrieu,
M. D. Anerella, [......],
S. Yen,
N. Yershov,
M. Yokoyama,
A. Zalewska,
J. Zalipska,
K. Zaremba,
M. Ziembicki,
E. D. Zimmerman,
M. Zito,
J. Zmuda
[show abstract]
[hide abstract]
ABSTRACT: The T2K experiment is a long-baseline neutrino oscillation experiment. Its
main goal is to measure the last unknown lepton sector mixing angle
{\theta}_{13} by observing {\nu}_e appearance in a {\nu}_{\mu} beam. It also
aims to make a precision measurement of the known oscillation parameters,
{\Delta}m^{2}_{23} and sin^{2} 2{\theta}_{23}, via {\nu}_{\mu} disappearance
studies. Other goals of the experiment include various neutrino cross section
measurements and sterile neutrino searches. The experiment uses an intense
proton beam generated by the J-PARC accelerator in Tokai, Japan, and is
composed of a neutrino beamline, a near detector complex (ND280), and a far
detector (Super-Kamiokande) located 295 km away from J-PARC. This paper
provides a comprehensive review of the instrumentation aspect of the T2K
experiment and a summary of the vital information for each subsystem.
06/2011;
-
KamLAND Collaboration,
S Abe,
K Furuno,
A. Gando,
Y. Gando,
K Ichimura,
H Ikeda,
K Inoue,
Y. Kibe,
W. Kimura, [......],
Y. Efremenko,
Y Kamyshkov,
O. Perevozchikov,
H. J. Karwowski,
D M Markoff,
W. Tornow,
K. M. Heeger,
F. Piquemal,
J. S. Ricol,
M. P. Decowski
[show abstract]
[hide abstract]
ABSTRACT: We report a measurement of the neutrino-electron elastic scattering rate from
8B solar neutrinos based on a 123 kton-day exposure of KamLAND. The
background-subtracted electron recoil rate, above a 5.5 MeV analysis threshold
is 1.49+/-0.14(stat)+/-0.17(syst) events per kton-day. Interpreted as due to a
pure electron flavor flux with a 8B neutrino spectrum, this corresponds to a
spectrum integrated flux of 2.77+/-0.26(stat)+/-0.32(syst) x 10^6 cm^-2s^-1.
The analysis threshold is driven by 208Tl present in the liquid scintillator,
and the main source of systematic uncertainty is due to background from
cosmogenic 11Be. The measured rate is consistent with existing measurements and
with Standard Solar Model predictions which include matter enhanced neutrino
oscillation.
06/2011;
-
S Abe,
T Ebihara,
S Enomoto,
K Furuno,
Y Gando,
K Ichimura,
H Ikeda,
K Inoue,
Y Kibe,
Y Kishimoto, [......],
W Bugg,
Y Efremenko,
Y Kamyshkov,
O Perevozchikov,
H J Karwowski,
D M Markoff,
W Tornow,
K M Heeger,
F Piquemal,
J-S Ricol
[show abstract]
[hide abstract]
ABSTRACT: The KamLAND experiment has determined a precise value for the neutrino oscillation parameter Deltam21(2) and stringent constraints on theta12. The exposure to nuclear reactor antineutrinos is increased almost fourfold over previous results to 2.44 x 10(32) proton yr due to longer livetime and an enlarged fiducial volume. An undistorted reactor nu[over]e energy spectrum is now rejected at >5sigma. Analysis of the reactor spectrum above the inverse beta decay energy threshold, and including geoneutrinos, gives a best fit at Deltam21(2)=7.58(-0.13)(+0.14)(stat) -0.15+0.15(syst) x 10(-5) eV2 and tan2theta12=0.56(-0.07)+0.10(stat) -0.06+0.10(syst). Local Deltachi2 minima at higher and lower Deltam21(2) are disfavored at >4sigma. Combining with solar neutrino data, we obtain Deltam21(2)=7.59(-0.21)+0.21 x 10(-5) eV2 and tan2theta12=0.47(-0.05)+0.06.
Physical Review Letters 06/2008; 100(22):221803. · 7.37 Impact Factor
-
T Araki,
S Enomoto,
K Furuno,
Y Gando,
K Ichimura,
H Ikeda,
K Inoue,
Y Kishimoto,
M Koga,
Y Koseki, [......],
A Kozlov,
Y Nakamura,
H J Karwowski,
D M Markoff,
R M Rohm,
W Tornow,
R Wendell,
M-J Chen,
Y-F Wang,
F Piquemal
[show abstract]
[hide abstract]
ABSTRACT: The Kamioka Liquid scintillator Anti-Neutrino Detector is used in a search for single neutron or two-neutron intranuclear disappearance that would produce holes in the -shell energy level of (12)C nuclei. Such holes could be created as a result of nucleon decay into invisible modes (inv), e.g., n--> 3v or nn--> 2v. The deexcitation of the corresponding daughter nucleus results in a sequence of space and time-correlated events observable in the liquid scintillator detector. We report on new limits for one- and two-neutron disappearance: tau(n--> inv) > 5.8 x 10(29) years and tau (nn--> inv) > 1.4 x 10(30) years at 90% C.L. These results represent an improvement of factors of approximately 3 and >10(4) and over previous experiments.
Physical Review Letters 03/2006; 96(10):101802. · 7.37 Impact Factor
-
T Araki,
S Enomoto,
K Furuno,
Y Gando,
K Ichimura,
H Ikeda,
K Inoue,
Y Kishimoto,
M Koga,
Y Koseki, [......],
Y Nakamura,
H J Karwowski,
D M Markoff,
K Nakamura,
R M Rohm,
W Tornow,
R Wendell,
M-J Chen,
Y-F Wang,
F Piquemal
[show abstract]
[hide abstract]
ABSTRACT: The detection of electron antineutrinos produced by natural radioactivity in the Earth could yield important geophysical information. The Kamioka liquid scintillator antineutrino detector (KamLAND) has the sensitivity to detect electron antineutrinos produced by the decay of 238U and 232Th within the Earth. Earth composition models suggest that the radiogenic power from these isotope decays is 16 TW, approximately half of the total measured heat dissipation rate from the Earth. Here we present results from a search for geoneutrinos with KamLAND. Assuming a Th/U mass concentration ratio of 3.9, the 90 per cent confidence interval for the total number of geoneutrinos detected is 4.5 to 54.2. This result is consistent with the central value of 19 predicted by geophysical models. Although our present data have limited statistical power, they nevertheless provide by direct means an upper limit (60 TW) for the radiogenic power of U and Th in the Earth, a quantity that is currently poorly constrained.
Nature 08/2005; 436(7050):499-503. · 36.28 Impact Factor
-
T Araki,
K Eguchi,
S Enomoto,
K Furuno,
K Ichimura,
H Ikeda,
K Inoue,
K Ishihara,
T Iwamoto,
T Kawashima, [......],
D M Markoff,
J A Messimore,
K Nakamura,
R M Rohm,
W Tornow,
R Wendell,
A R Young,
M-J Chen,
Y-F Wang,
F Piquemal
[show abstract]
[hide abstract]
ABSTRACT: We present results of a study of neutrino oscillation based on a 766 ton/year exposure of KamLAND to reactor antineutrinos. We observe 258 nu (e) candidate events with energies above 3.4 MeV compared to 365.2+/-23.7 events expected in the absence of neutrino oscillation. Accounting for 17.8+/-7.3 expected background events, the statistical significance for reactor nu (e) disappearance is 99.998%. The observed energy spectrum disagrees with the expected spectral shape in the absence of neutrino oscillation at 99.6% significance and prefers the distortion expected from nu (e) oscillation effects. A two-neutrino oscillation analysis of the KamLAND data gives Deltam(2)=7.9(+0.6)(-0.5)x10(-5) eV(2). A global analysis of data from KamLAND and solar-neutrino experiments yields Deltam(2)=7.9(+0.6)(-0.5)x10(-5) eV(2) and tan((2)theta=0.40(+0.10)(-0.07), the most precise determination to date.
Physical Review Letters 04/2005; 94(8):081801. · 7.37 Impact Factor
-
K Eguchi,
S Enomoto,
K Furuno,
H Ikeda,
K Ikeda,
K Inoue,
K Ishihara,
T Iwamoto,
T Kawashima,
Y Kishimoto, [......],
C R Gould,
H J Karwowski,
D M Markoff,
J A Messimore,
K Nakamura,
R M Rohm,
W Tornow,
A R Young,
M-J Chen,
Y-F Wang
[show abstract]
[hide abstract]
ABSTRACT: Data corresponding to a KamLAND detector exposure of 0.28 kton yr has been used to search for nu;(e)'s in the energy range 8.3<E(nu;(e))<14.8 MeV. No candidates were found for an expected background of 1.1+/-0.4 events. This result can be used to obtain a limit on nu;(e) fluxes of any origin. Assuming that all nu;(e) flux has its origin in the Sun and has the characteristic 8B solar nu(e) energy spectrum, we obtain an upper limit of 3.7 x 10(2) cm(-2) s(-1) (90% C.L.) on the nu;(e) flux. We interpret this limit, corresponding to 2.8 x 10(-4) of the standard solar model 8B nu(e) flux, in the framework of spin-flavor precession and neutrino decay models.
Physical Review Letters 02/2004; 92(7):071301. · 7.37 Impact Factor
-
K Eguchi,
S Enomoto,
K Furuno,
J Goldman,
H Hanada,
H Ikeda,
K Ikeda,
K Inoue,
K Ishihara,
W Itoh, [......],
L De Braeckeleer,
C R Gould,
H J Karwowski,
D M Markoff,
J A Messimore,
K Nakamura,
R M Rohm,
W Tornow,
A R Young,
Y-F Wang
[show abstract]
[hide abstract]
ABSTRACT: KamLAND has measured the flux of nu;(e)'s from distant nuclear reactors. We find fewer nu;(e) events than expected from standard assumptions about nu;(e) propagation at the 99.95% C.L. In a 162 ton.yr exposure the ratio of the observed inverse beta-decay events to the expected number without nu;(e) disappearance is 0.611+/-0.085(stat)+/-0.041(syst) for nu;(e) energies >3.4 MeV. In the context of two-flavor neutrino oscillations with CPT invariance, all solutions to the solar neutrino problem except for the "large mixing angle" region are excluded.
Physical Review Letters 01/2003; 90(2):021802. · 7.37 Impact Factor
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B E Berger,
J. Busenitz,
T. Classen,
M. P. Decowski,
D. A. Dwyer,
G. Elor,
A. Frank,
S. J. Freedman,
B. K. Fujikawa,
M. Galloway, [......],
K. Tolich,
W Bugg,
Y. Efremenko,
Y Kamyshkov,
O. Perevozchikov,
H. J. Karwowski,
D M Markoff,
W. Tornow,
F. Piquemal,
J. S. Ricol
[show abstract]
[hide abstract]
ABSTRACT: We have successfully built and operated a source deployment system for the KamLAND detector. This system was used to position radioactive sources throughout the delicate 1-kton liquid scintillator volume, while meeting stringent material cleanliness, material compatibility, and safety requirements. The calibration data obtained with this device were used to fully characterize detector position and energy reconstruction biases. As a result, the uncertainty in the size of the detector fiducial volume was reduced by a factor of two. Prior to calibration with this system, the fiducial volume was the largest source of systematic uncertainty in measuring the number of antineutrinos detected by KamLAND. This paper describes the design, operation and performance of this unique calibration system.
-
K Anderson,
J.C Anjos,
D Ayres,
J. Beacom,
I. Bediaga,
A. de Bellefon, B E Berger,
C. Buck,
W Bugg,
J. Busenitz, [......],
E Von Toerne,
D. Vigaud,
C Wagner,
Y F Wang,
Z Wang,
W. Winter,
H Wong,
E. Yakushev,
C G Yang,
O. Yasuda
