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Belle Collaboration,
R. Mizuk,
D. M. Asner,
A. Bondar,
T. K. Pedlar,
I. Adachi,
H. Aihara,
K. Arinstein,
V. Aulchenko,
T. Aushev, [......],
M. Watanabe,
Y. Watanabe,
K. M. Williams,
E. Won,
B. D. Yabsley,
J. Yamaoka,
Y. Yamashita,
C. Z. Yuan,
Z. P. Zhang,
V. Zhilich
[show abstract]
[hide abstract]
ABSTRACT: We report the first evidence for the eta_b(2S) using the
h_b(2P)->eta_b(2S)gamma transition and the first observation of the
h_b(1P)->eta_b(1S)gamma and h_b(2P)->eta_b(1S)gamma transitions. The mass and
width of the eta_b(1S) and eta_b(2S) are measured to be
m_etab(1S)=(9402.4+-1.5+-1.8)MeV/c^2, m_etab(2S)=(9999.0+-3.5 +2.8-1.9)MeV/c^2
and Gamma_etab(1S)=(10.8 +4.0-3.7 +4.5-2.0)MeV. We also update the h_b(1P) and
h_b(2P) mass measurements. We use a 133.4/fb data sample collected at energies
near the Upsilon(5S) resonance with the Belle detector at the KEKB
asymmetric-energy e+e- collider.
05/2012;
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[show abstract]
[hide abstract]
ABSTRACT: This paper develops a parallel fast multipole method specialized for uniform brick elements to achieve large-scale micromagnetic simulations of a practical perpendicular recording head within acceptable computation time. In highly parallel computation, it is indispensable to equally distribute the computing load among processes so as to obtain the good parallel speedup. The load balancing technique which can be regarded as the domain decomposition method based on octree structure in the fast multipole method is discussed. The scalability of the parallel fast multipole accelerated micromagnetic simulation is investigated with 100 or more MPI processes.
IEEE Transactions on Magnetics 11/2011; · 1.36 Impact Factor
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Super-Kamiokande Collaboration: K. Abe,
Y. Hayato,
T Iida,
K Ishihara,
J. Kameda,
Y. Koshio,
A. Minamino,
C. Mitsuda,
M Miura,
S Moriyama, [......],
Y Totsuka,
S Chen,
Z Deng,
Y Liu,
D. Kielczewska,
H. G. Berns,
K. K. Shiraishi,
E. Thrane,
K. Washburn,
R. J. Wilkes
[show abstract]
[hide abstract]
ABSTRACT: A search for neutron-antineutron (n - nbar) oscillation, a process with
|\DeltaB| = 2 that has been predicted by right-left (R-L) symmetric gauge
theories, was undertaken using the 24.5\times10^33 neutron-yrs exposure of
Super- Kamiokande I, in an analysis that included the significant sources of
experimental uncertainties. No evidence for n - nbar oscillation was found, the
lower limit of the lifetime for neutrons bound in ^16 O was determined to be
1.89 \times 10^32 yrs at the 90% confidence level (C.L.), and the corresponding
limit for the oscillation time for free neutrons was calculated to be 2.44
\times 10^8 sec using a theoretical suppression factor of 1.0 \times 10^23
sec^-1.
09/2011;
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[show abstract]
[hide abstract]
ABSTRACT: This paper investigates the scalability of a parallel fast multipole accelerated boundary integral equation method in electrostatic field analyses. A load balancing technique suitable for highly parallel computation with 100 or more processes, which is a domain decomposition method based on octree structure in the FMM, is also proposed. Numerical results clarify the effectiveness of the developed method in practical models with complicated geometry.
IEEE Transactions on Magnetics 06/2011; · 1.36 Impact Factor
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Procedia CS. 01/2011; 4:1456-1465.
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S. Fukuda,
Y. Fukuda,
M. Ishitsuka,
Y. Itow,
T. Kajita,
J. Kameda,
K. Kaneyuki,
K. Kobayashi,
Y. Koshio,
M. Miura, [......],
M. Koshiba,
Y. Ichikawa,
K. Nishijima,
H. Fujiyasu,
H. Ishino,
M. Morii,
Y. Watanabe,
D. Kielczewska,
A. L. Stachyra,
R. J. Wilkes
[show abstract]
[hide abstract]
ABSTRACT: Using the Super-Kamiokande neutrino observatory, a search was conducted for neutrinos produced in coincidence with gamma-ray bursts observed by the Burst and Transient Source Experiment detector. Super-Kamiokande data in the neutrino energy range of 7 MeV ~ 100 TeV were analyzed. For gamma-ray bursts that occurred between 1996 April and 2000 May, no statistically significant signal in excess of the background levels was detected. Implied upper limits on associated gamma-ray burst neutrino production are presented.
The Astrophysical Journal 12/2008; 578(1):317. · 6.02 Impact Factor
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M. Ikeda,
A. Takeda,
Y. Fukuda,
M. R. Vagins,
K. Abe,
T. Iida,
K. Ishihara,
J. Kameda,
Y. Koshio,
A. Minamino, [......],
Y. Liu,
D. Kielczewska,
J. Zalipska,
H. Berns,
R. Gran,
K. K. Shiraishi,
A. Stachyra,
E. Thrane,
K. Washburn,
R. J. Wilkes
[show abstract]
[hide abstract]
ABSTRACT: We report the results of a search for neutrino bursts from supernova explosions using the Super-Kamiokande detector. Super-Kamiokande is sensitive to core-collapse supernova explosions via observation of their neutrino emissions. The expected number of events comprising such a burst is ~104, and the average energy of the neutrinos is in the range of a few tens of MeV for a core-collapse supernova explosion at a typical distance in our galaxy (10 kpc); this strong signal means that the detection efficiency anywhere within our galaxy and well past the Magellanic Clouds should be 100%. We examined a data set taken from 1996 May to 2001 July, and from 2002 December to 2005 October, corresponding to 2589.2 live days. However, there is no evidence of such a supernova explosion during the data-taking period. The 90% C.L. upper limit on the rate of core-collapse supernova explosions out to distances of 100 kpc is found to be 0.32 SN yr-1.
The Astrophysical Journal 12/2008; 669(1):519. · 6.02 Impact Factor
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K. Abe,
J. Hosaka,
T. Iida,
K. Ishihara,
J. Kameda,
Y. Koshio,
A. Minamino,
C. Mitsuda,
M. Miura,
S. Moriyama, [......],
M. Koshiba,
D. Kielczewska,
J. Zalipska,
H. Berns,
R. Gran,
K. K. Shiraishi,
A. Stachyra,
E. Thrane,
K. Washburn,
R. J. Wilkes
[show abstract]
[hide abstract]
ABSTRACT: We present the results from several studies used to search for astrophysical sources of high-energy neutrinos using the Super-Kamiokande I (1996 April-2001 July) neutrino-induced upward-going muon data. The data set consists of 2359 events with minimum energy 1.6 GeV, of which 1892 are through-going and 467 stop within the detector. The results of several independent analyses are presented, including searches for point sources using directional and temporal information and a search for signatures of cosmic-ray interactions with the interstellar medium in the upward-going muons. No statistically significant evidence for point sources or any diffuse flux from the plane of the Galaxy was found, so specific limits on fluxes from likely point sources are calculated. The 90% confidence level (CL) upper limits on upward-going muon flux from astronomical sources that are located in the southern hemisphere and always under the horizon for Super-Kamiokande are ~ × 10-15 cm-2 s-1.
The Astrophysical Journal 12/2008; 652(1):198. · 6.02 Impact Factor
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S. Mine,
J. L. Alcaraz,
S. Andringa,
S. Aoki,
J. Argyriades,
K. Asakura,
R. Ashie,
F. Berghaus,
H. Berns,
H. Bhang, [......],
S. Yamada,
Y. Yamada,
S. Yamamoto,
C. Yanagisawa,
N. Yershov,
H. Yokoyama,
M. Yokoyama,
J. Yoo,
M. Yoshida,
J. Zalipska
[show abstract]
[hide abstract]
ABSTRACT: The atmospheric neutrino background for proton decay via p→e+π0 in ring imaging water Cherenkov detectors is studied with an artificial accelerator neutrino beam for the first time. In total, 3.14×105 neutrino events corresponding to about 10 megaton-years of atmospheric neutrino interactions were collected by a 1000 ton water Cherenkov detector (KT). The KT charged-current single π0 production data are well reproduced by simulation programs of neutrino and secondary hadronic interactions used in the Super-Kamiokande (SK) proton decay search. The obtained p→e+π0 background rate by the KT data for SK from the atmospheric neutrinos whose energies are below 3 GeV is 1.63-0.33+0.42(stat)-0.51+0.45(syst)(megaton-year)-1. This result is also relevant to possible future, megaton-scale water Cherenkov detectors.
Phys. Rev. D. 02/2008; 77(3).
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K Abe,
Y Hayato,
T Iida,
K Ishihara,
J Kameda,
Y Koshio,
A Minamino,
C Mitsuda,
M Miura,
S Moriyama, [......],
K Nishijima,
H Ishino,
Y Watanabe,
M Koshiba,
D Kielczewska,
J Zalipska,
H G Berns,
K K Shiraishi,
K Washburn,
R J Wilkes
[show abstract]
[hide abstract]
ABSTRACT: A search for the appearance of tau neutrinos from nu(mu) <--> nu(tau) oscillations in the atmospheric neutrinos has been performed using 1489.2 days of atmospheric neutrino data from the Super-Kamiokande-I experiment. A best fit tau neutrino appearance signal of 138+/-48(stat)-32(+15)(syst) events is obtained with an expectation of 78+/-26(syst). The hypothesis of no tau neutrino appearance is disfavored by 2.4 sigma.
Physical Review Letters 10/2006; 97(17):171801. · 7.37 Impact Factor
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S Yamamoto,
J Zalipska,
E Aliu,
S Andringa,
S Aoki,
J Argyriades,
K Asakura,
R Ashie,
F Berghaus,
H Berns, [......],
C W Walter,
W Wang,
R J Wilkes,
S Yamada,
C Yanagisawa,
N Yershov,
H Yokoyama,
M Yokoyama,
J Yoo,
M Yoshida
[show abstract]
[hide abstract]
ABSTRACT: We performed an improved search for nu(mu) --> nu(e) oscillation with the KEK to Kamioka (K2K) long-baseline neutrino oscillation experiment, using the full data sample of 9.2 x 10(19) protons on target. No evidence for a nu(e) appearance signal was found, and we set bounds on the nu(mu) --> nu(e) oscillation parameters. At Deltam(2)=2.8 x 10(-3) eV(2), the best-fit value of the K2Knu(mu) disappearance analysis, we set an upper limit of sin(2)2theta(mue) < 0.13 at a 90% confidence level.
Physical Review Letters 06/2006; 96(18):181801. · 7.37 Impact Factor
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M Hasegawa,
E Aliu,
S Andringa,
S Aoki,
J Argyriades,
K Asakura,
R Ashie,
H Berns,
H Bhang,
A Blondel, [......],
R J Wilkes,
S Yamada,
S Yamamoto,
C Yanagisawa,
N Yershov,
H Yokoyama,
M Yokoyama,
J Yoo,
M Yoshida,
J Zalipska
[show abstract]
[hide abstract]
ABSTRACT: We report the result from a search for charged-current coherent pion production induced by muon neutrinos with a mean energy of 1.3 GeV. The data are collected with a fully active scintillator detector in the K2K long-baseline neutrino oscillation experiment. No evidence for coherent pion production is observed, and an upper limit of is set on the cross section ratio of coherent pion production to the total charged-current interaction at 90% confidence level. This is the first experimental limit for coherent charged pion production in the energy region of a few GeV.
Physical Review Letters 01/2006; 95(25):252301. · 7.37 Impact Factor
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E Aliu,
S Andringa,
S Aoki,
J Argyriades,
K Asakura,
R Ashie,
H Berns,
H Bhang,
A Blondel,
S Borghi, [......],
R J Wilkes,
S Yamada,
S Yamamoto,
C Yanagisawa,
N Yershov,
H Yokoyama,
M Yokoyama,
J Yoo,
M Yoshida,
J Zalipska
[show abstract]
[hide abstract]
ABSTRACT: We present results for nu(mu) oscillation in the KEK to Kamioka (K2K) long-baseline neutrino oscillation experiment. K2K uses an accelerator-produced nu(mu) beam with a mean energy of 1.3 GeV directed at the Super-Kamiokande detector. We observed the energy-dependent disappearance of nu(mu), which we presume have oscillated to nu(tau). The probability that we would observe these results if there is no neutrino oscillation is 0.0050% (4.0 sigma).
Physical Review Letters 04/2005; 94(8):081802. · 7.37 Impact Factor
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S. Desai,
Y. Ashie,
S. Fukuda,
Y. Fukuda,
K. Ishihara,
Y. Itow,
Y. Koshio,
A. Minamino,
M. Miura,
S. Moriyama, [......],
H. Ishino,
M. Morii,
R. Nishimura,
Y. Watanabe,
D. Kielczewska,
J. Zalipska,
R. Gran,
K. K. Shiraishi,
K. Washburn,
R. J. Wilkes
Physical review D: Particles and fields 10/2004; 70(10):109901.
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Y Ashie,
J Hosaka,
K Ishihara,
Y Itow,
J Kameda,
Y Koshio,
A Minamino,
C Mitsuda,
M Miura,
S Moriyama, [......],
R Nishimura,
Y Watanabe,
D Kielczewska,
J Zalipska,
H G Berns,
R Gran,
K K Shiraishi,
A Stachyra,
K Washburn,
R J Wilkes
[show abstract]
[hide abstract]
ABSTRACT: Muon neutrino disappearance probability as a function of neutrino flight length L over neutrino energy E was studied. A dip in the L/E distribution was observed in the data, as predicted from the sinusoidal flavor transition probability of neutrino oscillation. The observed L/E distribution constrained nu(micro)<-->nu(tau) neutrino oscillation parameters; 1.9x10(-3)<Deltam(2)<3.0x10(-3) eV(2) and sin((2)2theta>0.90 at 90% confidence level.
Physical Review Letters 10/2004; 93(10):101801. · 7.37 Impact Factor
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D W Liu,
Y Ashie,
S Fukuda,
Y Fukuda,
K Ishihara,
Y Itow,
Y Koshio,
A Minamino,
M Miura,
S Moriyama, [......],
H Ishino,
M Morii,
R Nishimura,
Y Watanabe,
D Kielczewska,
J Zalipska,
R Gran,
K K Shiraishi,
K Washburn,
R J Wilkes
[show abstract]
[hide abstract]
ABSTRACT: A search for a nonzero neutrino magnetic moment has been conducted using 1496 live days of solar neutrino data from Super-Kamiokande-I. Specifically, we searched for distortions to the energy spectrum of recoil electrons arising from magnetic scattering due to a nonzero neutrino magnetic moment. In the absence of a clear signal, we found micro(nu)</=(3.6x10(-10))micro(B) at 90% C.L. by fitting to the Super-Kamiokande day-night spectra. The fitting took into account the effect of neutrino oscillation on the shapes of energy spectra. With additional information from other solar neutrino and KamLAND experiments constraining the oscillation region, a limit of micro(nu)</=(1.1x10(-10))micro(B) at 90% C.L. was obtained.
Physical Review Letters 07/2004; 93(2):021802. · 7.37 Impact Factor
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M H Ahn,
S Aoki,
Y Ashie,
H Bhang,
S Boyd,
D Casper,
J H Choi,
S Fukuda,
Y Fukuda,
R Gran, [......],
C W Walter,
W Wang,
R J Wilkes,
S Yamada,
S Yamamoto,
C Yanagisawa,
H Yokoyama,
J Yoo,
M Yoshida,
J Zalipska
[show abstract]
[hide abstract]
ABSTRACT: We present a search for electron neutrino appearance from accelerator-produced muon neutrinos in the K2K long-baseline neutrino experiment. One candidate event is found in the data corresponding to an exposure of 4.8 x 10(19) protons on target. The expected background in the absence of neutrino oscillations is estimated to be 2.4+/-0.6 events and is dominated by misidentification of events from neutral current pi(0) production. We exclude the nu(micro) to nu(e) oscillations at 90% C.L. for the effective mixing angle in the 2-flavor approximation of sin((2)2theta(microe)( approximately 1/2sin((2)2theta(13))>0.15 at Deltam(2)(microe)=2.8 x 10(-3) eV(2), the best-fit value of the nu(micro) disappearance analysis in K2K. The most stringent limit of sin((2)2theta(microe)<0.09 is obtained at Deltam(2)(microe)=6 x 10(-3) eV(2).
Physical Review Letters 07/2004; 93(5):051801. · 7.37 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: Algebraic multigrid (AMG) methods are known to be efficient black-box solvers for linear systems of equations, which are the results of the electromagnetic finite element formulations. This paper studies the parallel processing of an AMG solver employing shared memory computers for fast electromagnetic finite edge-element analyses. To efficiently parallelize AMG iterations, it is important to apply a parallel AMG smoother that can attain high scalability. We utilize the symmetric Gauss-Seidel (GS) method with multicolor (MC) ordering as the smoother. Advantages of the developed MC-GS smoother are that (1) the convergence of the solver does not depend on the number of processors employed, and (2) the coloring algorithm requires only information of the coefficient matrix. The latter property is suitable for black-box solvers. The numerical results of the sample eddy-current analysis demonstrate the parallel performance of the developed AMG solver in comparison with the conventional localized incomplete Cholesky conjugate gradient (ICCG) solver. The parallel AMG solver attains nearly the ideal speed-up of the analysis, while the localized ICCG solver obtains relatively low parallel efficiency using a large number of processors.
Progress in Electromagnetic Research Symposium. 04/2004;
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Super-Kamiokande Collaboration: S. Desai,
Y. Ashie,
S Fukuda,
Y Fukuda,
K Ishihara,
Y. Itow,
Y. Koshio,
A. Minamino,
M Miura,
S Moriyama, [......],
H. Ishino,
M Morii,
R Nishimura,
Y Watanabe,
D. Kielczewska,
J. Zalipska,
R. Gran,
K. K. Shiraishi,
K. Washburn,
R. J. Wilkes
[show abstract]
[hide abstract]
ABSTRACT: We present the results of indirect searches for Weakly Interacting Massive Particles (WIMPs) with 1679.6 live days of data from the Super-Kamiokande detector using neutrino-induced upward through-going muons. The search is performed by looking for an excess of high energy muon neutrinos from WIMP annihilations in the Sun, the core of the Earth, and the Galactic Center, as compared to the number expected from the atmospheric neutrino background. No statistically significant excess was seen. We calculate flux limits in various angular cones around each of the above celestial objects. We obtain conservative model-independent upper limits on WIMP-nucleon cross-section as a function of WIMP mass and compare these results with the corresponding results from direct dark matter detection experiments. Comment: 10 pages, 14 figures, Submitted to Phys. Rev. D
04/2004;
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J. Yoo,
Y. Ashie,
S. Fukuda,
Y. Fukuda,
K. Ishihara,
Y. Itow,
Y. Koshio,
A. Minamino,
M. Miura,
S. Moriyama, [......],
K. Nishijima,
H. Ishino,
M. Morii,
R. Nishimura,
Y. Watanabe,
D. Kielczewska,
H. G. Berns,
S. C. Boyd,
A. L. Stachyra,
R. J. Wilkes
[show abstract]
[hide abstract]
ABSTRACT: A search for periodic modulations of the solar neutrino flux was performed using the Super-Kamiokande-I data taken from 31 May 1996 to 15 July 2001. The detector’s capability of measuring the exact time of events, combined with a relatively high yield of solar neutrino events, allows a search for short-time variations in the observed flux. We employed the Lomb test to look for periodic modulations of the observed solar neutrino flux. The obtained periodogram is consistent with statistical fluctuation and no significant periodicity was found.
Phys. Rev. D. 11/2003; 68(9).
