研究者業績
基本情報
- 所属
- 千葉大学 ハドロン宇宙国際研究センター 教授 (センター長)
- 学位
- 博士(理学)
- ORCID ID
https://orcid.org/0000-0003-2480-5105- J-GLOBAL ID
- 201901004226160990
- researchmap会員ID
- B000361295
受賞
1-
2019年11月
論文
286-
PHYSICAL REVIEW D 82(7) 2010年10月 査読有りWe report on the results of the search for extremely-high energy neutrinos with energies above 10(7) GeV obtained with the partially (similar to 30%) constructed IceCube in 2007. From the absence of signal events in the sample of 242.1 days of effective live time, we derive a 90% C.L. model independent differential upper limit based on the number of signal events per energy decade at E-2 phi(ve+v mu+v tau) similar or equal to 1.4 x 10(-6) GeV cm(-2) sec(-1) sr(-1) for neutrinos in the energy range from 3 x 10(7) to 3 x 10(9) GeV.
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EUROPEAN PHYSICAL JOURNAL C 69(3-4) 361-378 2010年10月 査読有りWe present the search for Cherenkov signatures from relativistic magnetic monopoles in data taken with the AMANDA-II detector, a neutrino telescope deployed in the Antarctic ice cap at the Geographic South Pole. The non-observation of a monopole signal in data collected during the year 2000 improves present experimental limits on the flux of relativistic magnetic monopoles: Our flux limit varies between 3.8x10(-17) cm(-2) s(-1) sr(-1) (for monopoles moving at the vacuum speed of light) and 8.8x10(-16) cm(-2) s(-1) sr(-1) (for monopoles moving at a speed beta=v/c=0.76, just above the Cherenkov threshold in ice). These limits apply to monopoles that are energetic enough to penetrate the Earth and enter the detector from below the horizon. The limit obtained for monopoles reaching the detector from above the horizon is less stringent by roughly an order of magnitude, due to the much larger background from down-going atmospheric muons. This looser limit is however valid for a larger class of magnetic monopoles, since the monopoles are not required to pass through the Earth.
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ASTROPHYSICAL JOURNAL LETTERS 718(2) L194-L198 2010年8月 査読有りWe report the first observation of an anisotropy in the arrival direction of cosmic rays with energies in the multi-TeV region in the Southern sky using data from the IceCube detector. Between 2007 June and 2008 March, the partially deployed IceCube detector was operated in a configuration with 1320 digital optical sensors distributed over 22 strings at depths between 1450 and 2450 m inside the Antarctic ice. IceCube is a neutrino detector, but the data are dominated by a large background of cosmic-ray muons. Therefore, the background data are suitable for high-statistics studies of cosmic rays in the southern sky. The data include 4.3 billion muons produced by downward-going cosmic-ray interactions in the atmosphere; these events were reconstructed with a median angular resolution of 3 degrees and a median energy of similar to 20 TeV. Their arrival direction distribution exhibits an anisotropy in right ascension with a first-harmonic amplitude of (6.4 +/- 0.2 stat. +/- 0.8 syst.) x 10(-4).
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ASTROPARTICLE PHYSICS 34(1) 48-58 2010年8月 査読有りThe muon and anti-muon neutrino energy spectrum is determined from 2000-2003 AMANDA telescope data using regularised unfolding. This is the first measurement of atmospheric neutrinos in the energy range 2-200 TeV. The result is compared to different atmospheric neutrino models and it is compatible with the atmospheric neutrinos from pion and kaon decays. No significant contribution from charm had-ron decays or extraterrestrial neutrinos is detected. The capabilities to improve the measurement of the neutrino spectrum with the successor experiment IceCube are discussed. (c) 2010 Elsevier B.V. All rights reserved.
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ASTROPARTICLE PHYSICS 33(5-6) 277-286 2010年6月 査読有りWe have measured the speed of both pressure waves and shear waves as a function of depth between 80 and 500 m depth in South Pole ice with better than 1% precision. The measurements were made using the South Pole Acoustic Test Setup (SPATS), an array of transmitters and sensors deployed in the ice at the South Pole in order to measure the acoustic properties relevant to acoustic detection of astrophysical neutrinos. The transmitters and sensors use piezoceramics operating at similar to 5-25 kHz. Between 200 m and 500 m depth, the measured profile is consistent with zero variation of the sound speed with depth, resulting in zero refraction, for both pressure and shear waves. We also performed a complementary study featuring an explosive signal propagating vertically from 50 to 2250 m depth, from which we determined a value for the pressure wave speed consistent with that determined for shallower depths, higher frequencies, and horizontal propagation with the SPATS sensors. The sound speed profile presented here can be used to achieve good acoustic source position and emission time reconstruction in general, and neutrino direction and energy reconstruction in particular. The reconstructed quantities could also help separate neutrino signals from background. (C) 2010 Elsevier B.V. All rights reserved.
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NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT 618(1-3) 139-152 2010年6月 査読有りOver 5000 PMTs are being deployed at the South Pole to compose the IceCube neutrino observatory. Many are placed deep in the ice to detect Cherenkov light emitted by the products of high-energy neutrino interactions, and others are frozen into tanks on the surface to detect particles from atmospheric cosmic ray showers. IceCube is using the 10-in. diameter R7081-02 made by Hamamatsu Photonics. This paper describes the laboratory characterization and calibration of these PMTs before deployment. PMTs were illuminated with pulses ranging from single photons to saturation level. Parameterizations are given for the single photoelectron charge spectrum and the saturation behavior. Time resolution, late pulses and afterpulses are characterized. Because the PMTs are relatively large, the cathode sensitivity uniformity was measured. The absolute photon detection efficiency was calibrated using Rayleigh-scattered photons from a nitrogen laser. Measured characteristics are discussed in the context of their relevance to IceCube event reconstruction and simulation efforts. (C) 2010 Elsevier B.V. All rights reserved.
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PHYSICAL REVIEW D 81(5) 2010年3月 査読有りA search for muon neutrinos from Kaluza-Klein dark matter annihilations in the Sun has been performed with the 22-string configuration of the IceCube neutrino detector using data collected in 104.3 days of live time in 2007. No excess over the expected atmospheric background has been observed. Upper limits have been obtained on the annihilation rate of captured lightest Kaluza-Klein particle (LKP) WIMPs in the Sun and converted to limits on the LKP-proton cross sections for LKP masses in the range 250-3000 GeV. These results are the most stringent limits to date on LKP annihilation in the Sun.
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ASTROPHYSICAL JOURNAL 710(1) 346-359 2010年2月 査読有りWe present the results of searches for high-energy muon neutrinos from 41 gamma-ray bursts (GRBs) in the northern sky with the IceCube detector in its 22 string configuration active in 2007/2008. The searches cover both the prompt and a possible precursor emission as well as a model-independent, wide time window of -1 hr to + 3 hr around each GRB. In contrast to previous searches with a large GRB population, we do not utilize a standard Waxman-Bahcall GRB flux for the prompt emission but calculate individual neutrino spectra for all 41 GRBs from the burst parameters measured by satellites. For all of the three time windows, the best estimate for the number of signal events is zero. Therefore, we place 90% CL upper limits on the fluence from the prompt phase of 3.7 x 10(-3) erg cm(-2) (72 TeV-6.5 PeV) and on the fluence from the precursor phase of 2.3 x 10(-3) erg cm(-2) (2.2-55 TeV), where the quoted energy ranges contain 90% of the expected signal events in the detector. The 90% CL upper limit for the wide time window is 2.7 x 10(-3) erg cm(-2) (3 TeV-2.8 PeV) assuming an E-2 flux.
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ASTROPHYSICAL JOURNAL 708(1) 911-912 2010年1月 査読有り
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AIP Conference Proceedings 1238 365-368 2010年 査読有り
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PHYSICAL REVIEW LETTERS 103(22) 2009年11月 査読有りPoint source searches with the IceCube neutrino telescope have been restricted to one hemisphere, due to the exclusive selection of upward going events as a way of rejecting the atmospheric muon background. We show that the region above the horizon can be included by suppressing the background through energy-sensitive cuts. This improves the sensitivity above PeV energies, previously not accessible for declinations of more than a few degrees below the horizon due to the absorption of neutrinos in Earth. We present results based on data collected with 22 strings of IceCube, extending its field of view and energy reach for point source searches. No significant excess above the atmospheric background is observed in a sky scan and in tests of source candidates. Upper limits are reported, which for the first time cover point sources in the southern sky up to EeV energies.
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ASTROPHYSICAL JOURNAL 701(2) 1721-1731 2009年8月 査読有りWe report on a search with the IceCube detector for high-energy muon neutrinos from GRB 080319B, one of the brightest gamma-ray bursts (GRBs) ever observed. The fireball model predicts that a mean of 0.1 events should be detected by IceCube for a bulk Lorentz boost of the jet of 300. In both the direct on-time window of 66 s and an extended window of about 300 s around the GRB, no excess was found above background. The 90% CL upper limit on the number of track-like events from the GRB is 2.7, corresponding to a muon neutrino fluence limit of 9.5 x 10(-3) erg cm(-2) in the energy range between 120 TeV and 2.2 PeV, which contains 90% of the expected events.
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ASTROPHYSICAL JOURNAL LETTERS 701(1) L47-L51 2009年8月 査読有りWe present new results of searches for neutrino point sources in the northern sky, using data recorded in 2007-2008 with 22 strings of the IceCube detector (approximately one-fourth of the planned total) and 275.7 days of live time. The final sample of 5114 neutrino candidate events agrees well with the expected background of atmospheric muon neutrinos and a small component of atmospheric muons. No evidence of a point source is found, with the most significant excess of events in the sky at 2.2 sigma after accounting for all trials. The average upper limit over the northern sky for point sources of muon-neutrinos with E(-2) spectrum is E(2) Phi(v mu) < 1.4 x 10(-11) TeV cm(-2) s(-1), in the energy range from 3 TeV to 3 PeV, improving the previous best average upper limit by the AMANDA-II detector by a factor of 2.
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PHYSICAL REVIEW D 79(10) 2009年5月 査読有りThe AMANDA-II detector, operating since 2000 in the deep ice at the geographic South Pole, has accumulated a large sample of atmospheric muon neutrinos in the 100 GeV to 10 TeV energy range. The zenith angle and energy distribution of these events can be used to search for various phenomenological signatures of quantum gravity in the neutrino sector, such as violation of Lorentz invariance or quantum decoherence. Analyzing a set of 5511 candidate neutrino events collected during 1387 days of livetime from 2000 to 2006, we find no evidence for such effects and set upper limits on violation of Lorentz invariance and quantum decoherence parameters using a maximum likelihood method. Given the absence of evidence for new flavor-changing physics, we use the same methodology to determine the conventional atmospheric muon neutrino flux above 100 GeV.
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PHYSICAL REVIEW LETTERS 102(20) 2009年5月 査読有りA search for muon neutrinos from neutralino annihilations in the Sun has been performed with the IceCube 22-string neutrino detector using data collected in 104.3 days of live time in 2007. No excess over the expected atmospheric background has been observed. Upper limits have been obtained on the annihilation rate of captured neutralinos in the Sun and converted to limits on the weakly interacting massive particle (WIMP) proton cross sections for WIMP masses in the range 250-5000 GeV. These results are the most stringent limits to date on neutralino annihilation in the Sun.
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NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT 601(3) 294-316 2009年4月 査読有りIceCube is a km-scale neutrino observatory under construction at the South Pole with sensors both in the deep ice (InIce) and on the surface (IceTop). The sensors, called Digital Optical Modules (DOMs). detect, digitize and timestamp the signals from optical Cherenkov-radiation photons. The DOM Main Board (MB) data acquisition subsystem is connected to the central DAQ in the IceCube Laboratory (ICL) by a single twisted copper wire-pair and transmits packetized data on demand. Time calibration is maintained throughout the array by regular transmission to the DOMs of precisely timed analog signals, synchronized to a central GPS-disciplined clock. The design goals and consequent features, functional capabilities, and initial performance of the DOM MB, and the operation of a combined array of DOMs as a system, are described here. Experience with the first InIce strings and the IceTop stations indicates that the system design and performance goals have been achieved. (c) 2009 Elsevier B.V. All rights reserved.
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PHYSICAL REVIEW D 79(6) 2009年3月 査読有りWe present a search for point sources of high energy neutrinos using 3.8 yr of data recorded by AMANDA-II during 2000-2006. After reconstructing muon tracks and applying selection criteria designed to optimally retain neutrino-induced events originating in the northern sky, we arrive at a sample of 6595 candidate events, predominantly from atmospheric neutrinos with primary energy 100 GeV to 8 TeV. Our search of this sample reveals no indications of a neutrino point source. We place the most stringent limits to date on E-2 neutrino fluxes from points in the northern sky, with an average upper limit of E-2 Phi(nu mu)+nu(tau)<= 5.2x10(-11) TeV cm(-2) s(-1) on the sum of nu(mu) and nu(tau) fluxes, assumed equal, over the energy range from 1.9 TeV to 2.5 PeV.
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Nuclear Physics B - Proceedings Supplements 190(C) 26-31 2009年 査読有り
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Journal of the Physical Society of Japan 78(SUPPL. A) 108-113 2009年 査読有り
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31st International Cosmic Ray Conference, ICRC 2009 2009年 査読有り
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ASTROPHYSICAL JOURNAL 675(2) 1014-1024 2008年3月 査読有りA search for diffuse neutrinos with energies in excess of 10(5) GeV is conducted with AMANDA-II data recorded between 2000 and 2002. Above 10(7) GeV, the Earth is essentially opaque to neutrinos. This fact, combined with the limited overburden of the AMANDA-II detector ( roughly 1.5 km), concentrates these ultra-high-energy neutrinos at the horizon. The primary background for this analysis is bundles of downgoing, high-energy muons from the interaction of cosmic rays in the atmosphere. No statistically significant excess above the expected background is seen in the data, and an upper limit is set on the diffuse all-flavor neutrino flux of E-2 Phi(90%CL) < 2.7x10(-7) GeV cm(-2) s(-1) sr(-1) valid over the energy range of 2x10(5) to 10(9) GeV. A number of models that predict neutrino fluxes from active galactic nuclei are excluded at the 90% confidence level.
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ASTROPHYSICAL JOURNAL 674(1) 357-370 2008年2月 査読有りWe present the results of the analysis of neutrino observations by the Antarctic Muon and Neutrino Detector Array (AMANDA) correlated with photon observations of more than 400 gamma-ray bursts (GRBs) in the northern hemisphere from 1997 to 2003. During this time period, AMANDA's effective collection area for muon neutrinos was larger than that of any other existing detector. After the application of various selection criteria to our data, we expect similar to 1 neutrino event and <2 background events. Based on our observations of zero events during and immediately prior to the GRBs in the data set, we set the most stringent upper limit on muon neutrino emission correlated with GRBs. Assuming a Waxman-Bahcall spectrum and incorporating all systematic uncertainties, our flux upper limit has a normalization at 1 PeV of E-2 Phi(nu) <= 6.3 x 10(-9) GeV cm(-2) s(-1) sr(-1), with 90% of the events expected within the energy range of similar to 10 TeV to similar to 3 PeV. The impact of this limit on several theoretical models of GRBs is discussed, as well as the future potential for detection of GRBs by next-generation neutrino telescopes. Finally, we briefly describe several modifications to this analysis in order to apply it to other types of transient point sources.
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NUCLEAR PHYSICS B-PROCEEDINGS SUPPLEMENTS 175(SUPPL.: COMPLETE) 237-240 2008年1月 査読有りThe motivations, characteristics and potential performance of the JEM-EUSO project are briefly discussed.
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Nuclear Physics B - Proceedings Supplements 175-176(SUPPL.: COMPLETE) 221-226 2008年 査読有り
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Astrophysical Journal 689(1 PART 2) 2008年 査読有り
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Physical Review D - Particles, Fields, Gravitation and Cosmology 77(8) 2008年 査読有り
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Journal of the Physical Society of Japan 77(SUPPL. B) 71-75 2008年 査読有りIceCube is a new high-energy neutrino telescope which will be coming online in the near future. IceCube will be capable of measuring fluxes of all three flavors of neutrino, and its peak neutrino energy sensitivity will be in the TeV-PeV range. Here, after a brief description of the detector, we describe its anticipated performance with a selection of physics topics: supernovae, extraterrestrial diffuse and point sources of neutrinos, gamma-ray bursts, neutrinos from WIMP annihilation, and cosmic ray composition. © 2008 The Physical Society of Japan.
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NUCLEAR PHYSICS B-PROCEEDINGS SUPPLEMENTS 175(SUPPL.: COMPLETE) 407-408 2008年1月 査読有り
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PHYSICAL REVIEW D 76(4) 2007年8月 査読有りA search for TeV-PeV muon neutrinos from unresolved sources was performed on AMANDA-II data collected between 2000 and 2003 with an equivalent live time of 807 days. This diffuse analysis sought to find an extraterrestrial neutrino flux from sources with nonthermal components. The signal is expected to have a harder spectrum than the atmospheric muon and neutrino backgrounds. Since no excess of events was seen in the data over the expected background, an upper limit of E-2 Phi(90%C.L.)< 7.4x10(-8) GeV cm(-2) s(-1) sr(-1) is placed on the diffuse flux of muon neutrinos with a Phi proportional to E-2 spectrum in the energy range 16 TeV to 2.5 PeV. This is currently the most sensitive Phi proportional to E-2 diffuse astrophysical neutrino limit. We also set upper limits for astrophysical and prompt neutrino models, all of which have spectra different from Phi proportional to E-2.
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ASTROPHYSICAL JOURNAL 664(1) 397-410 2007年7月 査読有りUsing the neutrino telescope AMANDA-II, we have conducted two analyses searching for neutrino-induced cascades fromgamma-ray bursts. No evidence of astrophysical neutrinos was found, and limits are presented for several models. We also present neutrino effective areas which allow the calculation of limits for any neutrino production model. The first analysis looked for a statistical excess of events within a sliding window of 1 or 100 s ( for short and long burst classes, respectively) during the years 2001-2003. The resulting upper limit on the diffuse flux normalization times E-2 for the Waxman-Bahcall model at 1 PeV is 1.6 x 10(-6) GeVcm(-2) s(-1) sr(-1) (a factor of 120 above the theoretical prediction). For this search 90% of the neutrinos would fall in the energy range 50 TeV to 7 PeV. The second analysis looked for neutrino-induced cascades in coincidence with 73 bursts detected by BATSE in the year 2000. The resulting upper limit on the diffuse flux normalization times E-2, also at 1 PeV is 1.5 x 10(-6) GeV cm(-2) s(-1) sr(-1) (a factor of 110 above the theoretical prediction) for the same energy range. The neutrino-induced cascade channel is complementary to the up-going muon channel. We comment on its advantages for searches of neutrinos from GRBs and its future use with IceCube.
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PHYSICAL REVIEW D 76(2) 2007年7月 査読有りThe IceCube neutrino detector is a cubic kilometer TeV to PeV neutrino detector under construction at the geographic South Pole. The dominant population of neutrinos detected in IceCube is due to meson decay in cosmic-ray air showers. These atmospheric neutrinos are relatively well understood and serve as a calibration and verification tool for the new detector. In 2006, the detector was approximately 10% completed, and we report on data acquired from the detector in this configuration. We observe an atmospheric neutrino signal consistent with expectations, demonstrating that the IceCube detector is capable of identifying neutrino events. In the first 137.4 days of live time, 234 neutrino candidates were selected with an expectation of 211 +/- 76.1(syst)+/- 14.5(stat) events from atmospheric neutrinos.
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PHYSICAL REVIEW D 75(10) 2007年5月 査読有りWe report the results of a five-year survey of the northern sky to search for point sources of high energy neutrinos. The search was performed on the data collected with the AMANDA-II neutrino telescope in the years 2000 to 2004, with a live time of 1001 days. The sample of selected events consists of 4282 upward going muon tracks with high reconstruction quality and an energy larger than about 100 GeV. We found no indication of point sources of neutrinos and set 90% confidence level flux upper limits for an all-sky search and also for a catalog of 32 selected sources. For the all-sky search, our average (over declination and right ascension) experimentally observed upper limit Phi(0)=(E/1 TeV)(gamma)center dot d Phi/dE to a point source flux of muon and tau neutrino (detected as muons arising from taus) is Phi(nu mu)+nu(0)(mu)+Phi(nu tau)+nu(0)(tau)=11.1x 10(-11) TeV-1 cm(-2) s(-1), in the energy range between 1.6 TeV and 2.5 PeV for a flavor ratio Phi(nu mu)+nu(0)(mu)/Phi(nu tau)+nu(0)(tau)=1 and assuming a spectral index gamma=2. It should be noticed that this is the first time we set upper limits to the flux of muon and tau neutrinos. In previous papers we provided muon neutrino upper limits only neglecting the sensitivity to a signal from tau neutrinos, which improves the limits by 10% to 16%. The value of the average upper limit presented in this work corresponds to twice the limit on the muon neutrino flux Phi(nu mu)+nu(0)(mu)=5.5x10(-11) TeV-1 cm(-2) s(-1). A stacking analysis for preselected active galactic nuclei and a search based on the angular separation of the events were also performed. We report the most stringent flux upper limits to date, including the results of a detailed assessment of systematic uncertainties.
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AIP Conference Proceedings 903 626-629 2007年 査読有り
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Proceedings of the 30th International Cosmic Ray Conference, ICRC 2007 4(HE PART 1) 417-420 2007年 査読有り
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Proceedings of the 30th International Cosmic Ray Conference, ICRC 2007 5(HE PART 2) 1159-1162 2007年 査読有り
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Proceedings of the 30th International Cosmic Ray Conference, ICRC 2007 5(HE PART 2) 1109-1112 2007年 査読有り
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Proceedings of the 30th International Cosmic Ray Conference, ICRC 2007 5(HE PART 2) 1013-1016 2007年 査読有り
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Proceedings of the TeV Particle Astrophysics II Workshop 60(1) 14-19 2007年 査読有りThe controversial results of the cosmic ray energy spectrum at extremely-high energies (EHE) can be interpreted from the same source model(s) by taking into account rather large statistical and systematic errors of the present measurements. In addition we might have considered too simple pictures on possible EHE cosmic ray sources. Taking into account possible range of the extragalactic magnetic field configuration in clusters of galaxies, the source distribution in space, and primary particle emission intensities at each source leads to non-unique solutions of energy spectrum at earth, which makes it more difficult to resolve the long-standing mysteries on generation mechanism and sites that can produce a particle of such high energies. An alternative and complementary approach to study their origin is to explore EHE universe by penetrating neutral charge particles - neutrinos. What we can learn from measurements of EHE cosmic neutrinos are discussed. We finally present a detection possibility by the IceCube neutrino observatory.
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PHYSICAL REVIEW LETTERS 97(22) 2006年12月 査読有りOn 27 December 2004, a giant gamma flare from the Soft Gamma-Ray Repeater 1806-20 saturated many satellite gamma-ray detectors, being the brightest transient event ever observed in the Galaxy. AMANDA-II was used to search for down-going muons indicative of high-energy gammas and/or neutrinos from this object. The data revealed no significant signal, so upper limits (at 90% C.L.) on the normalization constant were set: 0.05(0.5) TeV-1 m(-2) s(-1) for gamma=-1.47 (-2) in the gamma flux and 0.4(6.1) TeV-1 m(-2) s(-1) for gamma=-1.47 (-2) in the high-energy neutrino flux.
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ASTROPARTICLE PHYSICS 26(4-5) 282-300 2006年11月 査読有りThe sensitivity of a search for sources of TeV neutrinos can be improved by grouping potential sources together into generic classes in a procedure that is known as source stacking. In this paper, we define catalogs of Active Galactic Nuclei (AGN) and use them to perform a source stacking analysis. The grouping of AGN into classes is done in two steps: first, AGN classes are defined, then, sources to be stacked are selected assuming that a potential neutrino flux is linearly correlated with the photon luminosity in a certain energy band (radio, IR, optical, keV, GeV, TeV). Lacking any secure detailed knowledge on neutrino production in AGN, this correlation is motivated by hadronic AGN models, as briefly reviewed in this paper. The source stacking search for neutrinos from generic AGN classes is illustrated using the data collected by the AMANDA-II highenergy neutrino detector during the year 2000. No significant excess for any of the suggested groups was found. (c) 2006 Elsevier B.V. All rights reserved.
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ASTROPARTICLE PHYSICS 26(3) 155-173 2006年10月 査読有りThe first sensors of the IceCube neutrino observatory were deployed at the South Pole during the austral summer of 2004-2005 and have been producing data since February 2005. One string of 60 sensors buried in the ice and a surface array of eight ice Cherenkov tanks took data until December 2005 when deployment of the next set of strings and tanks began. We have analyzed these data, demonstrating that the performance of the system meets or exceeds design requirements. Times are determined across the whole array to a relative precision of better than 3 ns, allowing reconstruction of muon tracks and light bursts in the ice, of air-showers in the surface array and of events seen in coincidence by surface and deep-ice detectors separated by up to 2.5 km. (c) 2006 Elsevier B.V. All rights reserved.
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ASTROPARTICLE PHYSICS 26(2) 129-139 2006年9月 査読有りA search has been performed for nearly vertically upgoing neutrino-induced muons with the Antarctic Muon And Neutrino Detector Array (AMANDA), using data taken over the three year period 1997-99. No excess above the expected atmospheric neutrino background has been found. Upper limits at 90% confidence level have been set on the annihilation rate of neutralinos at the center of the Earth, as well as on the muon flux at AMANDA induced by neutrinos created by the annihilation products. (c) 2006 Elsevier B.V. All rights reserved.
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Frascati Physics Series 42(SPEC. ISS.) 87-101 2006年 査読有り
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11th International Conference on Elastic and Diffractive Scattering: Towards the High Energy Frontiers, EDS 2005 2005年The Telescope Array (TA) experiment is designed to observe cosmic-ray-induced air showers at extremely high energies. It is being deployed in a desert of Utah, USA; an array of 3 m2 scintillation counters will be distributed over 760 km2 and 3 sets of air fluorescence telescopes will be placed in the perimeter of the array. It's primary purpose is to make a decisive measurement of the cosmic ray spectrum in the GZK cutoff region. We expect the first data from the TA in the spring of 2007. As its unique features are included 1) hybrid measurement planned down to 1017.5 eV, 2) calibration of fluorescence detection by using artificial air showers generated by an electron linac, 3) interaction model calibration by the LHC.
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Proceedings of the 29th International Cosmic Ray Conference Vol 8: HE 1.5 8 177-180 2005年 査読有りThe installation of The Telescope Array experiment started in earnest. Since observation by combine two different type air shower detector, we aim to search super GZK cosmic ray and determine accurately the energy of these CRs. In past, extensive air shower observations using scintillation detector array give many good results Utilize these experience, we combine scintillator array and fluorescence detectors for determination for EAS energy scale, core position and incoming direction. In this paper, we introduce the electronics and data acquisition system for our scintillator array; call Surface Detector (SD). The engineering array that constituted 18 scintillation detectors was installed on December 2004. We have tested our electronics and DAQ on this small array. Complete SD will have 576 detectors, around 900 km(2). This will be about 9 times larger than AGASA.
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NUCLEAR PHYSICS B-PROCEEDINGS SUPPLEMENTS 138(1-3) 179-182 2005年1月 査読有りThe IceCube neutrino telescope, a huge neutrino telescope with 1 cubic km instrumented volume, starts construction in 2004. The project status and the expected sensitivity and performance for detecting high-energy cosmic neutrinos are reported. The capability of EHE neutrino detection is also briefly mentioned.
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Proceedings of the 29th International Cosmic Ray Conference Vol 8: HE 1.5 8 141-144 2005年 査読有りThe Telescope Array (TA) is the air shower experiment designed for observing extremely high energy cosmic rays. It consists of an array of scintillation counters covering the ground area of 760 km(2) and 3 sets of air fluorescence telescopes placed in the perimeter of the array. The TA aims at making a decisive measurement of the cosmic ray spectrum in the GZK cutoff region, and pinning down the nature of cosmic rays exceeding 10(20) eV, which have been the subject of extensive studies by AGASA, HiRes and other air shower experiments. The TA is being constructed in Utah, USA, and the commissioning is expected in the spring of 2007. An extension of hybrid measurement is planned down to 1017. 5 eV in order to elucidate the galactic to extra-galactic transition of cosmic ray sources (TALE proposal).
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29th International Cosmic Ray Conference, ICRC 2005 8 193-196 2005年 査読有り
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Proceedings of the 29th International Cosmic Ray Conference Vol 8: HE 1.5 8 181-184 2005年 査読有りThe telescope Array (TA) experiment, currently under construction in Utah, USA, is an array of surface detectors with air fluorescence telescopes to study the highest energy cosmic rays of energy beyond 10(20)eV. The TA surface detector array will consist of 576 plastic scintillation counters, on a square grid with 1.2 km spacing, covering the ground area of 760 km. Each surface detector is outfitted with two layers of scintillators of 3m(2) area, readout electronics, and wireless LAN communication system, which are powered by solar system. The test of an Engineering Array with 18 surface detectors is currently operating after being deployed in December 2004. Here we present the design and the progress of the surface detectors of TA, focusing on the status of the Engineering Array.
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29th International Cosmic Ray Conference, ICRC 2005 10 297-302 2005年 査読有り
MISC
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日本物理学会講演概要集 68(2) 102-102 2013年8月26日
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日本物理学会講演概要集 62(2) 117-117 2007年8月21日
所属学協会
1共同研究・競争的資金等の研究課題
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