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1.
  • Abt, I, et al. (author)
  • Inclusive V-0 production cross sections from 920 GeV fixed target proton-nucleus collisions
  • 2003
  • In: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 29:2, s. 181-190
  • Journal article (peer-reviewed)abstract
    • Inclusive differential cross sections dsigma(pA)/dx(F) and dsigma(pA)/dp(t)(2) for the production of K-S(0), Lambda, and (&ULambda;) over bar particles are measured at HERA in proton-induced reactions on C, Al, Ti, and W targets. The incident beam energy is 920 GeV, corresponding to roots = 41.6 GeV in the proton-nucleon system. The ratios of differential cross sections dsigma(pA)(K-S(0))/dsigma(pA)(Lambda) and dsigma(pA)((&ULambda;) over bar)/dsigma(pA) (Lambda) are measured to be 6.2 +/- 0.5 and 0.66 +/- 0.07, respectively, for x(F) approximate to -0.06. No significant dependence upon the target material is observed. Within errors, the slopes of the transverse momentum distributions da,Ald t also show no significant dependence upon the target material. The dependence of the extrapolated total cross sections sigma(pA) on the atomic mass A of the target material is discussed, and the deduced cross sections per nucleon sigma(pN) are compared with results obtained at other energies.
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2.
  • Abt, I, et al. (author)
  • Measurement of the b(b)over-bar production cross section in 920 GeV fixed-target proton-nucleus collisions
  • 2003
  • In: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 26:3, s. 345-355
  • Journal article (peer-reviewed)abstract
    • Using the HERA-B detector, the b (b) over bar production cross section has been measured in 920 GeV proton collisions on carbon and titanium targets. The b (b) over bar production was tagged via inclusive bottom quark decays into J/psi by exploiting the longitudinal separation of J/psi --> l(+)l(-) decay vertices from the primary proton-nucleus interaction. Both e(+)e(-) and mu(+)mu(-) channels have been reconstructed and the combined analysis yields the cross section sigma(b (b) over bar) = 32(-12)(+14)(stat) (+6)(-7)(sys) nb/nucleon.
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3.
  • Adcox, K, et al. (author)
  • PHENIX detector overview
  • 2003
  • In: Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment. - 0167-5087. ; 499:2-3, s. 469-479
  • Journal article (peer-reviewed)abstract
    • The PHENIX detector is designed to perform a broad study of A-A, p-A, and p-p collisions to investigate nuclear matter under extreme conditions. A wide variety of probes, sensitive to all timescales, are used to study systematic variations with species and energy as well as to measure the spin structure of the nucleon. Designing for the needs of the heavy-ion and polarized-proton programs has produced a detector with unparalleled capabilities. PHENIX measures electron and muon pairs, photons, and hadrons with excellent energy and momentum resolution. The detector consists of a large number of subsystems that are discussed in other papers in this volume. The overall design parameters of the detector are presented. (C) 2002 Elsevier Science B.V. All rights reserved.
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4.
  • Ambrosio, M, et al. (author)
  • The MACRO detector at Gran Sasso
  • 2002
  • In: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier. - 0168-9002 .- 1872-9576. ; 486:3, s. 663-707
  • Journal article (peer-reviewed)abstract
    • MACRO was an experiment that ran in the Laboratori Nazionali del Gran Sasso from 1988 to 2000. Its principal goal was to observe magnetic monopoles or set significantly lower experimental flux limits than had been previously available in the velocity range from about beta = 10(-4) to unity. In addition it made a variety of other observations. Examples are: setting flux limits on other so far unobserved particles such as nuclearites and lightly ionizing particles, searching for WIMP annihilations in the Earth and the Sun and for neutrino bursts from stellar collapses in or near our Galaxy, and making measurements relevant to high energy muon and neutrino astronomy and of the flux of up-going muons as a function of nadir angle showing evidence for neutrino oscillations. The apparatus consisted of three principal types of detectors: liquid scintillator counters, limited streamer tubes, and nuclear track etch detectors. In addition, over part of its area it contained a transition radiation detector. The general design philosophy emphasized redundancy and complementarity. This paper describes the technical aspects of the complete MACRO detector, its operational performance, and the techniques used to calibrate it and verify its proper operation. It supplements a previously published paper which described the first portion of the detector that was built and operated. (C) 2002 Elsevier Science B.V. All rights reserved.
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5.
  • Aglietta, M, et al. (author)
  • The cosmic ray primary composition between 10(15) and 10(16) eV from Extensive Air Showers electromagnetic and TeV muon data
  • 2004
  • In: Astroparticle physics. - : Elsevier. - 0927-6505 .- 1873-2852. ; 20:6, s. 641-652
  • Journal article (peer-reviewed)abstract
    • The cosmic ray primary composition in the energy range between 10(15) and 10(16) eV, i.e., around the "knee" of the primary spectrum, has been studied through the combined measurements of the EAS-TOP air shower array (2005 m a. s.l., 10(5) m(2) collecting area) and the MACRO underground detector (963 m.a.s.l., 3100 m w.e. of minimum rock overburden, 920 m(2) effective area) at the National Gran Sasso Laboratories. The used observables are the air shower size (N-c) measured by EAS-TOP and the muon number (N-mu) recorded by MACRO. The two detectors are separated on average by 1200 m of rock, and located at a respective zenith angle of about 30degrees. The energy threshold at the surface for muons reaching the MACRO depth is approximately 1.3 TeV. Such muons are produced in the early stages of the shower development and in a kinematic region quite different from the one relevant for the usual N-mu - N-e studies. The measurement leads to a primary composition becoming heavier at the knee of the primary spectrum, the knee itself resulting from the steepening of the spectrum of a primary light component (p, He) of Deltay = 0.7 +/- 0.4 at E-0 similar to 4 x 10(15) eV. The result confirms the ones reported from the observation of the low energy muons at the surface (typically in the GeV energy range), showing that the conclusions do not depend on the production region kinematics. Thus, the hadronic interaction model used (CORSIKA/QGSJET) provides consistent composition results from data related to secondaries produced in a rapidity region exceeding the central one. Such an evolution of the composition in the knee region supports the "standard" galactic acceleration/propagation models that imply rigidity dependent breaks of the different components.. and therefore breaks occurring at lower energies in the spectra of the light nuclei. (C) 2003 Elsevier B.V. All rights reserved.
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6.
  • Aglietta, M, et al. (author)
  • The cosmic ray proton, helium and CNO fluxes in the 100 TeV energy region from TeV muons and EAS atmospheric Cherenkov light observations of MACRO and EAS-TOP
  • 2004
  • In: Astroparticle physics. - : Elsevier. - 0927-6505 .- 1873-2852. ; 21:3, s. 223-240
  • Journal article (peer-reviewed)abstract
    • The primary cosmic ray (CR) proton, helium and CNO fluxes in the energy range 80-300 TeV are studied at the National Gran Sasso Laboratories by means of EAS-TOP (Campo Imperatore, 2005 m a.s.l.) and MACRO (deep underground, 3100 m w.e., the surface energy threshold for a muon reaching the detector being E-mu(th) approximate to 1.3 TeV). The measurement is based on: (a) the selection of primaries based on their energy/nucleon (i.e., with energy/nucleon sufficient to produce a muon with energy larger than 1.3 TeV) and the reconstruction of the shower geometry by means of the muons recorded by MACRO in the deep underground laboratories; (b) the detection of the associated atmospheric Cherenkov light (C.l.) signals by means of the C.l. detector of EAS-TOP. The C.l. density at core distance r > 100 m is directly related to the total primary energy E-0. Proton and helium ("p + He") and proton, helium and CNO ("p + He + CNO") primaries are thus selected at E-0 approximate to 80 TeV, and at E-0 similar or equal to 250 TeV, respectively. Their flux is measured: J(p+He)(80 TeV) = (1.8 +/- 0.4) x 10(-6) m(-1)-s(-1) sr(-1) TeV-1, and J(p+He+CNO)(250 TeV) = (1.1 +/- 0.3) x 10(-7) m(-2)-s(-1) sr(-1) TeV-1, their relative weights being J(p+He)(J(p+He+CNO)) over bar (250 TeV) = 0.78 +/- 0.17. By using the measurements of the proton spectrum obtained from the direct experiments and hadron flux data in the atmosphere, we obtain for the relative weights of the three components at 250 TeV: J(p) : J(He) : J(CNO) = (0.20 +/- 0.08) : (0.58 +/- 0.19) : (0.22 +/- 0.17). This corresponds to the dominance of helium over proton primaries at 100-1000 TeV, and a possible non-negligible contribution from CNO. The lateral distribution of Cherenkov light in Extensive Air Showers (EASs), which is related to the rate of energy deposit of the primary in the atmosphere, is measured for a selected proton and helium primary beam, and good agreement is found when compared with the one calculated with the CORSIKA/QGSJET simulation model. (C) 2004 Elsevier B.V. All rights reserved.
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7.
  • Ambrosio, M, et al. (author)
  • Muon energy estimate through multiple scattering with the MACRO detector
  • 2002
  • In: Nuclear Instruments and Methods in Physics Research Section A. - 0168-9002 .- 1872-9576. ; 492:3, s. 376-386
  • Journal article (peer-reviewed)abstract
    • Muon energy measurement represents an important issue for any experiment addressing neutrino-induced up-going muon studies. Since the neutrino oscillation probability depends on the neutrino energy, a measurement of the muon energy adds an important piece of information concerning the neutrino system. We show in this paper how the MACRO limited streamer tube system can be operated in drift mode by using the TDCs included in the QTPs, an electronics designed for magnetic monopole search. An improvement of the space resolution is obtained, through an analysis of the multiple scattering of muon tracks as they pass through our detector. This information can be used further to obtain an estimate of the energy of muons crossing the detector. Here we present the results of two dedicated tests, performed at CERN PS-T9 and SPS-X7 beam lines, to provide a full check of the electronics and to exploit the feasibility of such a multiple scattering analysis. We show that by using a neural network approach, we are able to reconstruct the muon energy for E-mu < 40 GeV. The test beam data provide an absolute energy calibration, which allows us to apply this method to MACRO data. (C) 2002 Elsevier Science B.V. All rights reserved.
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8.
  • Ambrosio, M, et al. (author)
  • Atmospheric neutrino oscillations from upward throughgoing muon multiple scattering in MACRO
  • 2003
  • In: Physics Letters B. - 0370-2693 .- 1873-2445. ; 566:1-2, s. 35-44
  • Journal article (peer-reviewed)abstract
    • The energy of atmospheric neutrinos detected by MACRO was estimated using multiple Coulomb scattering of upward throughgoing muons. This analysis allows a test of atmospheric neutrino oscillations, relying on the distortion of the muon energy distribution. These results have been combined with those coming from the upward throughgoing muon angular distribution only. Both analyses are independent of the neutrino flux normalization and provide strong evidence, above the for level, in favour of neutrino oscillations. (C) 2003 Published by Elsevier B.V.
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9.
  • Ambrosio, M, et al. (author)
  • Final results of magnetic monopole searches with the MACRO experiment
  • 2002
  • In: European Physical Journal C. - : Springer. - 1434-6044 .- 1434-6052. ; 25:4, s. 511-522
  • Journal article (peer-reviewed)abstract
    • We present the final results obtained by the MACRO experiment in the search for GUT magnetic monopoles in the penetrating cosmic radiation, for the range 4 x 10(-5) < 3 < 1. Several searches with all the MACRO sub-detectors (i.e. scintillation counters, limited streamer tubes and nuclear track detectors) were performed, both in stand alone and combined ways. No candidates were detected and a 90% Confidence Level (C.L.) upper limit to the local magnetic monopole flux was set at the level of 1.4 x 10(-16) cm(-2) s(-1) sr(-1). This result is the first experimental limit obtained in direct searches which is well below the Parker bound in the whole 3 range in which GUT magnetic monopoles are,expected.
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10.
  • Ambrosio, M, et al. (author)
  • Search for cosmic ray sources using muons detected by the MACRO experiment
  • 2003
  • In: Astroparticle physics. - : Elsevier. - 0927-6505 .- 1873-2852. ; 18:6, s. 615-627
  • Journal article (peer-reviewed)abstract
    • The MACRO underground detector at Gran Sasso Laboratory recorded 60 million secondary cosmic ray muons from February 1989 until December 2000. Different techniques were used to analyze this sample in search for density excesses from astrophysical point-like sources. No evidence for DC excesses for any source in an all-sky survey is reported. In addition, searches for muon excess correlated with the known binary periods of Cygnus X-3 and Hercules X-1, and searches for statistically significant bursting episodes from known gamma-ray sources are also proved negative. (C) 2002 Elsevier Science B.V. All rights reserved.
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11.
  • Ambrosio, M, et al. (author)
  • Search for diffuse neutrino flux from astrophysical sources with MACRO
  • 2003
  • In: Astroparticle physics. - : Elsevier. - 0927-6505 .- 1873-2852. ; 19:1, s. 1-13
  • Journal article (peer-reviewed)abstract
    • Many galactic and extragalactic astrophysical sources are currently considered promising candidates as high-energy neutrino emitters. Astrophysical neutrinos can be detected as upward-going muons produced in charged-current interactions with the medium surrounding the detector. The expected neutrino fluxes from various models start to dominate on the atmospheric neutrino background at neutrino energies above some tens of TeV. We present the results of a search for an excess of high-energy upward-going muons among the sample of data collected by MACRO during similar to5.8 years of effective running time. No significant evidence for this signal was found. As a consequence, an upper limit on the flux of upward-going muons from high-energy neutrinos was set at the level of 1.7 x 10(-14) cm(-2) s(-1) sr(-1). The corresponding upper limit for the diffuse neutrino flux was evaluated assuming a neutrino power law spectrum. Our result was compared with theoretical predictions and upper limits from other experiments. (C) 2002 Elsevier Science B.V. All rights reserved.
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12.
  • Ambrosio, M, et al. (author)
  • Search for nucleon decays induced by GUT magnetic monopoles with the MACRO experiment
  • 2002
  • In: European Physical Journal C. - : Springer. - 1434-6044 .- 1434-6052. ; 26:2, s. 163-172
  • Journal article (peer-reviewed)abstract
    • The interaction of a Grand Unification Magnetic Monopole with a nucleon can lead to a barion-number violating process in which the nucleon decays into a lepton and one or more mesons (catalysis of nucleon decay). In this paper we report an experimental study of the effects of a catalysis process in the MACRO detector. Using a dedicated analysis we obtain new magnetic monopole (MM) flux upper limits at the level of similar to 3 (.) 10(-16) cm(-2) s(-1) sr(-1) for 1.1(.) 10(-4) less than or equal to \beta\ less than or equal to 5 (.) 10(-3), based on the search for catalysis events in the MACRO data. We also analyze the dependence of the MM flux limit on the catalysis cross section.
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13.
  • Ambrosio, M, et al. (author)
  • A combined analysis technique for the search for fast magnetic monopoles with the MACRO detector
  • 2002
  • In: Astroparticle physics. - : Elsevier. - 0927-6505 .- 1873-2852. ; 18:1, s. 27-41
  • Journal article (peer-reviewed)abstract
    • We describe a search method for fast moving (beta = v/c > 5 x 10(-3)) magnetic monopoles using simultaneously the scintillator, streamer tube and track-etch subdetectors of the MACRO apparatus. The first two subdetectors are used primarily for the identification of candidates while the track-etch one is used as the final tool for their rejection or confirmation. Using this technique, a first sample of more than two-years of data has been analyzed without any evidence of a magnetic monopole. We set a 90% CL upper limit to the local monopole flux of 1.5 x 10(-15) cm(-2) s(-1) sr(-1) in the velocity range 5 x 10(-3) less than or equal to beta less than or equal to 0.99 and for nucleon decay catalysis cross-section smaller than similar to1 mb (C) 2002 Elsevier Science B.V. All rights reserved.
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14.
  • Ambrosio, M, et al. (author)
  • Matter effects in upward-going muons and sterile neutrino oscillations
  • 2001
  • In: Physics Letters B. - : Elsevier. - 0370-2693 .- 1873-2445. ; 517:1-2, s. 59-66
  • Journal article (peer-reviewed)abstract
    • The angular distribution of upward-going muons produced by atmospheric neutrinos in the rock below the MACRO detector shows anomalies in good agreement with two flavor nu (mu) --> nu (tau) oscillations with maximum mixing and Deltam(2) around 0.0024 eV(2). Exploiting the dependence of magnitude of the matter effect on oscillation channel, and using a set of 809 upward-going muons observed in MACRO, we show that the two flavor nu (mu) --> nu (s) oscillation is disfavored with 99% C.L. with respect to nu (mu) --> nu (tau). (C) 2001 Elsevier Science B.V. All rights reserved.
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15.
  • Ambrosio, M, et al. (author)
  • Measurement of the residual energy of muons in the Gran Sasso underground laboratories
  • 2003
  • In: Astroparticle physics. - : Elsevier. - 0927-6505 .- 1873-2852. ; 19:3, s. 313-328
  • Journal article (peer-reviewed)abstract
    • The MACRO detector was located in the Hall B of the Gran Sasso underground laboratories under an average rock overburden of 3700 hg/cm(2). A transition radiation detector composed of three identical modules, covering a total horizontal area of 36 m(2), was installed inside the empty upper part of the detector in order to measure the residual energy of muons. This paper presents the measurement of the residual energy of single and double muons crossing the apparatus. Our data show that double muons are more energetic than single ones. This measurement is performed over a standard rock depth range from 3000 to 6500 hg/cm(2). (C) 2002 Elsevier Science B.V. All rights reserved.
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16.
  • Ambrosio, M, et al. (author)
  • Moon and Sun shadowing effect in the MACRO detector
  • 2003
  • In: Astroparticle physics. - : Elsevier. - 0927-6505 .- 1873-2852. ; 20:2, s. 145-156
  • Journal article (peer-reviewed)abstract
    • Using data collected by the MACRO experiment from 1989 to the end of its operations in 2000, we have studied in the underground muon flux the shadowing. effects due to both the Moon and the Sun. We have observed the shadow cast by the Moon at its apparent position with a significance of 6.5sigma. The Moon shadowing effect has been used to verify the pointing capability of the detector and to determine the instrument resolution for the search of muon excesses from any direction of the celestial sphere. The dependence of the effect on the geomagnetic field is clearly shown by splitting the data sample in day and night observations. The Sun shadow, observed with a significance of 4.6sigma is displaced by about 0.6degrees from its apparent position. In this case however the explanation resides in the configuration of the Solar and Interplanetary Magnetic Fields, which affect the propagation of cosmic ray particles between the Sun, and the Earth. The displacement of the Sun shadow with respect to the real Sun position has been used to establish an upper limit on the antimatter flux in cosmic rays of about 48% at 68% c.l. and primary energies of about 20 TeV. (C) 2003 Elsevier B.V. All rights reserved.
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17.
  • Ambrosio, M, et al. (author)
  • Search for the sidereal and solar diurnal modulations in the total MACRO muon data set
  • 2003
  • In: Physical Review D. Particles and fields. - : American Physical Society. - 0556-2821 .- 1089-4918. ; 67:4
  • Journal article (peer-reviewed)abstract
    • We have analyzed 44.3M single muons collected by MACRO from 1991 through 2000 in 2145 live days of operation. We have searched for the solar diurnal, apparent sidereal, and pseudosidereal modulation of the underground muon rate by computing hourly deviations of the muon rate from 6 month averages. We find evidence for statistically significant modulations with the solar diurnal and the sidereal periods. The amplitudes of these modulations are <0.1%, and are at the limit of the detector statistics. The pseudosidereal modulation is not statistically significant. The solar diurnal modulation is due to the daily atmospheric temperature variations at 20 km, the altitude of primary cosmic ray interactions with the atmosphere; MACRO is the deepest experiment to report this result. The sidereal modulation is in addition to the expected Compton-Getting modulation due to solar system motion relative to the local standard of rest; it represents motion of the solar system with respect to the galactic cosmic rays toward the galactic plane.
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18.
  • Ambrosio, M, et al. (author)
  • Measurements of atmospheric muon neutrino oscillations, global analysis of the data collected with MACRO detector
  • 2004
  • In: European Physical Journal C. - : Springer. - 1434-6044 .- 1434-6052. ; 36:3, s. 323-339
  • Journal article (peer-reviewed)abstract
    • The final analysis of atmospheric neutrino events collected with the MACRO detector is presented. Three different classes of events, generated by neutrinos in different energy ranges, are studied looking at rates, angular distributions and estimated energies. The results are consistent for all the subsamples and indicate a flux deficit that depends on energy and path - length of neutrinos. The no - oscillation hypothesis is excluded at similar to 5sigma, while the hypothesis of nu(mu) --> nu(tau) oscillation gives a satisfactory description of all data. The parameters with highest probability in a two flavor scenario are sin(2) 2theta(m) = 1 and Deltam(2) = 0.0023 eV(2). This result is independent of the absolute normalization of the atmospheric neutrino fluxes. The data can also be used to put experimental constrain on this normalization.
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19.
  • Adler, SS, et al. (author)
  • Elliptic flow of identified hadrons in Au+Au collisions at root s(NN)=200 GeV
  • 2003
  • In: Physical Review Letters. - 1079-7114. ; 91:18: 182301
  • Journal article (peer-reviewed)abstract
    • The anisotropy parameter (v(2)), the second harmonic of the azimuthal particle distribution, has been measured with the PHENIX detector in Au+Au collisions at roots(NN)=200 GeV for identified and inclusive charged particle production at central rapidities (eta<0.35) with respect to the reaction plane defined at high rapidities (eta=3-4 ). We observe that the v(2) of mesons falls below that of (anti)baryons for p(T)>2 GeV/c, in marked contrast to the predictions of a hydrodynamical model. A quark-coalescence model is also investigated.
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20.
  • Togo, V, et al. (author)
  • Calibrations of CR39 and Makrofol nuclear track detectors and search for exotic particles
  • 2003
  • In: Nuclear physics B, Proceedings supplements. - : Elsevier. - 0920-5632 .- 1873-3832. ; 125, s. 217-221
  • Journal article (peer-reviewed)abstract
    • We present the final results of the search for exotic massive particles in the cosmic radiation performed with the MACRO underground experiment. Magnetic monopoles and nuclearites flux upper limits obtained with the CR39 nuclear track subdetector, the scintillation and streamer tube subdetectors are given. Searches at high altitude with the SLIM experiment are in progress.
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21.
  • Adler, SS, et al. (author)
  • Bose-Einstein correlations of charged pion pairs in Au+Au collisions at root(NN)-N-s = 200 GeV
  • 2004
  • In: Physical Review Letters. - 1079-7114. ; 93:15
  • Journal article (peer-reviewed)abstract
    • Bose-Einstein correlations of identically charged pion pairs were measured by the PHENIX experiment at midrapidity in Au+Au collisions at roots(NN)=200 GeV. The Bertsch-Pratt radius parameters were determined as a function of the transverse momentum of the pair and as a function of the centrality of the collision. Using the standard core-halo partial Coulomb fits, and a new parametrization which constrains the Coulomb fraction as determined from the unlike-sign pion correlation, the ratio R-out/R-side is within 0.8-1.1 for 0.25<<1.2 GeV/c. The centrality dependence of all radii is well described by a linear scaling in N-part(1/3), and R-out/R-side for similar to0.45 GeV/c is approximately constant at unity as a function of centrality.
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22.
  • Adler, SS, et al. (author)
  • Double helicity asymmetry in inclusive midrapidity pi(0) production for polarized p+p collisions at root s=200 GeV
  • 2004
  • In: Physical Review Letters. - 1079-7114. ; 93:20: 202002
  • Journal article (peer-reviewed)abstract
    • We present a measurement of the double longitudinal spin asymmetry in inclusive pi(0) production in polarized proton-proton collisions at roots=200 GeV. The data were taken at the Relativistic Heavy Ion Collider with average beam polarizations of 0.27. The measurements are the first in a program to study the longitudinal spin structure of the proton, using strongly interacting probes, at collider energies. The asymmetry is presented for transverse momenta 1-5 GeV/c at midrapidity, where next-to-leading-order perturbative quantum chromodynamic (NLO pQCD) calculations well describe the unpolarized cross section. The observed asymmetry is small and is compared to a NLO pQCD calculation with a range of polarized gluon distributions.
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23.
  • Adler, SS, et al. (author)
  • J/psi production from proton-proton collisions at root s=200 GeV
  • 2004
  • In: Physical Review Letters. - 1079-7114. ; 92:5
  • Journal article (peer-reviewed)abstract
    • J/psi production has been measured in proton-proton collisions at roots=200 GeV over a wide rapidity and transverse momentum range by the PHENIX experiment at the Relativistic Heavy Ion Collider. Distributions of the rapidity and transverse momentum, along with measurements of the mean transverse momentum and total production cross section are presented and compared to available theoretical calculations. The total J/psi cross section is 4.0+/-0.6(stat)+/-0.6(syst)+/-0.4(abs) mub. The mean transverse momentum is 1.80+/-0.23(stat)+/-0.16(syst) GeV/c.
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24.
  • Adler, SS, et al. (author)
  • J/psi production in Au-Au collisions at root s(NN)=200 GeV
  • 2004
  • In: Physical Review C (Nuclear Physics). - 0556-2813. ; 69:1
  • Journal article (peer-reviewed)abstract
    • First results on charm quarkonia production in heavy ion collisions at the Relativistic Heavy Ion Collider (RHIC) are presented. The yield of J/psi's measured in the PHENIX experiment via electron-positron decay pairs at midrapidity for Au-Au reactions at roots(NN) = 200 GeV is analyzed as a function of collision centrality. For this analysis we have studied 49.3x10(6) minimum bias Au-Au reactions. We present the J/psi invariant yield dN/dy for peripheral and midcentral reactions. For the most central collisions where we observe no signal above background, we quote 90% confidence level upper limits. We compare these results with our J/psi measurement from proton-proton reactions at the same energy. We find that our measurements are not consistent with models that predict strong enhancement relative to binary collision scaling.
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25.
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26.
  • Adler, SS, et al. (author)
  • Scaling properties of proton and antiproton production in root s(NN)=200 GeV Au+Au collisions
  • 2003
  • In: Physical Review Letters. - 1079-7114. ; 91:17: 172301
  • Journal article (peer-reviewed)abstract
    • We report on the yield of protons and antiprotons, as a function of centrality and transverse momentum, in Au+Au collisions at rootS(NN)=200 GeV measured at midrapidity by the PHENIX experiment at the BNL Relativistic Heavy Ion Collider. In central collisions at intermediate transverse momenta (1.5
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27.
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28.
  • Ahrens, J., et al. (author)
  • Observation of high energy atmospheric neutrinos with the Antarctic muon and neutrino detector array
  • 2002
  • In: Physical Review D. - : American Physical Society. - 1550-7998 .- 1550-2368. ; 66:1, s. 120051-1200520
  • Journal article (peer-reviewed)abstract
    • The Antarctic muon and neutrino detector array (AMANDA) began collecting data with ten strings in 1997. Results from the first year of operation are presented. Neutrinos coming through the Earth from the Northern Hemisphere are identified by secondary muons moving upward through the array. Cosmic rays in the atmosphere generate a background of downward moving muons, which are about 106 times more abundant than the upward moving muons. Over 130 days of exposure, we observed a total of about 300 neutrino events. In the same period, a background of 1.05 × 109 cosmic ray muon events was recorded. The observed neutrino flux is consistent with atmospheric neutrino predictions. Monte Carlo simulations indicate that 90% of these events lie in the energy range 66 GeV to 3.4 TeV. The observation of atmospheric neutrinos consistent with expectations establishes AMANDA-B10 as a working neutrino telescope.
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29.
  • Imanishi, T., et al. (author)
  • Integrative annotation of 21,037 human genes validated by full-length cDNA clones
  • 2004
  • In: PLoS biology. - : Public Library of Science (PLoS). - 1544-9173 .- 1545-7885. ; 2:6, s. 856-875
  • Journal article (peer-reviewed)abstract
    • The human genome sequence defines our inherent biological potential; the realization of the biology encoded therein requires knowledge of the function of each gene. Currently, our knowledge in this area is still limited. Several lines of investigation have been used to elucidate the structure and function of the genes in the human genome. Even so, gene prediction remains a difficult task, as the varieties of transcripts of a gene may vary to a great extent. We thus performed an exhaustive integrative characterization of 41,118 full-length cDNAs that capture the gene transcripts as complete functional cassettes, providing an unequivocal report of structural and functional diversity at the gene level. Our international collaboration has validated 21,037 human gene candidates by analysis of high-quality full-length cDNA clones through curation using unified criteria. This led to the identification of 5,155 new gene candidates. It also manifested the most reliable way to control the quality of the cDNA clones. We have developed a human gene database, called the H-Invitational Database (H-InvDB; http://www.h-invitational.jp/). It provides the following: integrative annotation of human genes, description of gene structures, details of novel alternative splicing isoforms, non-protein-coding RNAs, functional domains, subcellular localizations, metabolic pathways, predictions of protein three-dimensional structure, mapping of known single nucleotide polymorphisms (SNPs), identification of polymorphic microsatellite repeats within human genes, and comparative results with mouse full-length cDNAs. The H-InvDB analysis has shown that up to 4% of the human genome sequence (National Center for Biotechnology Information build 34 assembly) may contain misassembled or missing regions. We found that 6.5% of the human gene candidates (1,377 loci) did not have a good protein-coding open reading frame, of which 296 loci are strong candidates for non-protein-coding RNA genes. In addition, among 72,027 uniquely mapped SNPs and insertions/deletions localized within human genes, 13,215 nonsynonymous SNPs, 315 nonsense SNPs, and 452 indels occurred in coding regions. Together with 25 polymorphic microsatellite repeats present in coding regions, they may alter protein structure, causing phenotypic effects or resulting in disease. The H-InvDB platform represents a substantial contribution to resources needed for the exploration of human biology and pathology.
  •  
30.
  • Adcox, K, et al. (author)
  • Flow Measurements via Two-Particle Azimuthal Correlations in Au+Au Collisions at sqrt[sNN]=130 GeV
  • 2002
  • In: Physical Review Letters. - 1079-7114. ; 89
  • Journal article (peer-reviewed)abstract
    • Two-particle azimuthal correlation functions are presented for charged hadrons produced in Au+Au collisions at the Relativistic Heavy Ion Collider (sqrt[sNN]=130 GeV). The measurements permit determination of elliptic flow without event-by-event estimation of the reaction plane. The extracted elliptic flow values (v2) show significant sensitivity to both the collision centrality and the transverse momenta of emitted hadrons, suggesting rapid thermalization and relatively strong velocity fields. When scaled by the eccentricity of the collision zone ε, the scaled elliptic flow shows little or no dependence on centrality for charged hadrons with relatively low pT. A breakdown of this ε scaling is observed for charged hadrons with pT >1.0 GeV/c.
  •  
31.
  • Adcox, K, et al. (author)
  • Net charge fluctuations in Au+Au interactions root s(NN)=130 GeV
  • 2002
  • In: Physical Review Letters. - 1079-7114. ; 89
  • Journal article (peer-reviewed)abstract
    • Data from Au+ Au interactions at s(NN)=130 GeV, obtained with the PHENIX detector at the Relativistic Heavy-Ion Collider, are used to investigate local net charge fluctuations among particles produced near midrapidity. According to recent suggestions, such fluctuations may carry information from the quark-gluon plasma. This analysis shows that the fluctuations are dominated by a stochastic distribution of particles, but are also sensitive to other effects, like global charge conservation and resonance decays.
  •  
32.
  • Andres, E., et al. (author)
  • Selected recent results from AMANDA
  • 2001
  • In: ICHEP 2000. Proceedings of the 30th International Conference on High Energy Physics. - : World Scientific. ; , s. 965-968
  • Conference paper (peer-reviewed)abstract
    • We present a selection of results based on data taken in 1997 with the 302-PMT Antarctic Muon and Neutrino Detector Array-B10 ("AMANDA-B10") array. Atmospheric neutrinos created in the northern hemisphere are observed indirectly through their charged current interactions which produce relativistic, Cherenkov-light-emitting upgoing muons in the South Pole ice cap. The reconstructed angular distribution of these events is in good agreement with expectation and demonstrates the viability of this ice-based device as a neutrino telescope. Studies of nearly vertical upgoing muons limit the available parameter space for WIMP dark matter under the assumption that WIMPS are trapped in the earth's gravitational potential well and annihilate with one another near the earth's center.
  •  
33.
  • Adcox, K, et al. (author)
  • Centrality dependence of the high (PT) charged hadron suppression in Au+Au collisions at root s(NN)=130 GeV
  • 2003
  • In: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - 0370-2693. ; 561:1-2, s. 82-92
  • Journal article (peer-reviewed)abstract
    • PHENIX has measured the centrality dependence of charged hadron p(T) spectra from Au +An collisions at root(s)NN = 130 GeV The truncated mean p(T) decreases with centrality for p(T) > 2 GeV/c, indicating an apparent reduction of the contribution from hard scattering to high p(T) hadrdn production. For central collisions the yield at high p(T) is shown to be suppressed compared to binary nucleon-nucleon collision scaling of p + p, data. This suppression is monotonically increasing with centrality, but most of the change occurs below 30% centrality, i.e., for collisions with less than similar to140 participating nucleons. The observed p(T) and centrality dependence is consistent with the particle production predicted by models including hard scattering and subsequent energy loss of the scattered partons in the dense matter created in the collisions. (C) 2003 Published by Elsevier Science B.V.
  •  
34.
  • Adcox, K, et al. (author)
  • Event-by-event fluctuations in mean p(T) and mean E(T) in root s(NN)=130 GeVAu+Au collisions
  • 2002
  • In: Physical Review C (Nuclear Physics). - 0556-2813. ; 66:2
  • Journal article (peer-reviewed)abstract
    • Distributions of event-by-event fluctuations of the mean transverse momentum and mean transverse energy near mid-rapidity have been measured in Au+Au collisions at roots(NN)=130 GeV at the Relativistic Heavy-Ion Collider. By comparing the distributions to what is expected for statistically independent particle emission, the magnitude of nonstatistical fluctuations in mean transverse momentum is determined to be consistent with zero. Also, no significant nonrandom fluctuations in mean transverse energy are observed. By constructing a fluctuation model with two event classes that preserve the mean and variance of the semi-inclusive p(T) or e(T) spectra, we exclude a region of fluctuations in roots(NN)=130 GeV Au+Au collisions.
  •  
35.
  • Adcox, K, et al. (author)
  • Measurement of Lambda and (Lambda)over-bar particles in Au plus Au collisions at root s(NN)=130 GeV
  • 2002
  • In: Physical Review Letters. - 1079-7114. ; 89:9
  • Journal article (peer-reviewed)abstract
    • We present results on the measurement of Lambda and (&ULambda;) over bar production in Au+Au collisions at roots(NN)=130 GeV with the PHENIX detector at the Relativistic Heavy Ion Collider. The transverse momentum spectra were measured for minimum bias and for the 5% most central events. The (&ULambda;) over bar/Lambda ratios are constant as a function of p(T) and the number of participants. The measured net Lambda density is significantly larger than predicted by models based on hadronic strings (e.g., HIJING) but in approximate agreement with models which include the gluon-junction mechanism.
  •  
36.
  • Adcox, K, et al. (author)
  • Measurement of single electrons and implications for charm production in Au+Au collisions at root(NN)-N-S=130 GeV
  • 2002
  • In: Physical Review Letters. - 1079-7114. ; 88:19
  • Journal article (peer-reviewed)abstract
    • Transverse momentum spectra of electrons from Au+Au collisions at roots(NN) = 130 GeV have been measured at midrapidity by the PHENIX experiment at the Relativistic Heavy Ion Collider. The spectra show an excess above the background from photon conversions and light hadron decays. The electron signal is consistent with that expected from semileptonic decays of charm. The yield of the electron signal dN(e)/dy for p(T) > 0.8 GeV/c is 0.025 +/- 0.004(stat) +/- 0.010( syst) in central collisions, and the corresponding charm cross section is 380 +/- 60(stat) +/- 200(syst ) mub per binary nucleon-nucleon collision.
  •  
37.
  • Adcox, K, et al. (author)
  • Suppression of hadrons with large transverse momentum in central Au+Au collisions at root s(NN)=130 GeV
  • 2002
  • In: Physical Review Letters. - 1079-7114. ; 88:2
  • Journal article (peer-reviewed)abstract
    • Transverse momentum spectra for charged hadrons and for neutral pions in the range 1 Gev/c < P-T < 5 GeV/c have been measured by the PHENIX experiment at RHIC in Au + Au collisions at rootS(NN) = 130 GeV. At high p(T) the spectra from peripheral nuclear collisions are consistent with scaling the spectra from p + p collisions by the average number of binary nucleon-nucleon collisions. The spectra from central collisions are significantly suppressed when compared to the binary-scaled p + p expectation, and also when compared to similarly binary-scaled peripheral collisions, indicating a novel nuclear-medium effect in central nuclear collisions at RHIC energies.
  •  
38.
  • Adcox, K, et al. (author)
  • Transverse-mass dependence of two-pion correlations in Au+Au collisions at root(NN)-N-S=130 GeV
  • 2002
  • In: Physical Review Letters. - 1079-7114. ; 88:19
  • Journal article (peer-reviewed)abstract
    • Two-pion correlations in roots(NN) = 130 GeV Au+Au collisions at RHIC have been measured over a broad range of pair transverse momentum k(T) by the PHENIX experiment at RHIC. The k(T) dependent transverse radii are similar to results from heavy-ion collisions at roots(NN) = 4.1 , 4.9, and 17.3 GeV, whereas the longitudinal radius increases monotonically with beam energy. The ratio of the outwards to sidewards transverse radii (R-out/R-side) is consistent with unity and independent of k(T) .
  •  
39.
  • Ahrens, J., et al. (author)
  • Search for neutrino-induced cascades with the AMANDA detector
  • 2003
  • In: Physical Review D. - : American Physical Society (APS). - 1550-7998 .- 1550-2368. ; 67:1, s. 012003-
  • Journal article (peer-reviewed)abstract
    • We report on a search for electromagnetic and/or hadronic showers (cascades) induced by a diffuse flux of neutrinos with energies between 5 TeV and 300 TeV from extraterrestrial sources. Cascades may be produced by matter interactions of all flavors of neutrinos, and contained cascades have better energy resolution and afford better background rejection than throughgoing νμ-induced muons. Data taken in 1997 with the AMANDA detector were searched for events with a high-energy cascadelike signature. The observed events are consistent with expected backgrounds from atmospheric neutrinos and catastrophic energy losses from atmospheric muons. Effective volumes for all flavors of neutrinos, which allow the calculation of limits for any neutrino flux model, are presented. The limit on cascades from a diffuse flux of νe+ νμ + ντ+ ν̄e + ν̄μ+ ν̄τ is E2(dΦ/dE)<9.8×10-6 GeV cm-2 s-1 sr-1, assuming a neutrino flavor flux ratio of 1:1:1 at the detector. The limit on cascades from a diffuse flux of νe+ν̄e is E2(dΦ/dE)<6. 5×10-6 GeV cm-2 s-1 sr-1, independent of the assumed neutrino flavor flux ratio. © 2003 The American Physical Society.
  •  
40.
  • Andrés, E., et al. (author)
  • Observation of high-energy neutrinos using Čerenkov detectors embedded deep in Antarctic ice
  • 2001
  • In: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 410:6827, s. 441-443
  • Journal article (peer-reviewed)abstract
    • Neutrinos are elementary particles that carry no electric charge and have little mass. As they interact only weakly with other particles, they can penetrate enormous amounts of matter, and therefore have the potential to directly convey astrophysical information from the edge of the Universe and from deep inside the most cataclysmic high-energy regions. The neutrino's great penetrating power, however, also makes this particle difficult to detect. Underground detectors have observed low-energy neutrinos from the Sun and a nearby supernova2, as well as neutrinos generated in the Earth's atmosphere. But the very low fluxes of high-energy neutrinos from cosmic sources can be observed only by much larger, expandable detectors in, for example, deep water3,4 or ice5. Here we report the detection of upwardly propagating atmospheric neutrinos by the ice-based Antarctic muon and neutrino detector array (AMANDA). These results establish a technology with which to build a kilometre-scale neutrino observatory necessary for astrophysical observations1.
  •  
41.
  • Andrés, E., et al. (author)
  • Recent results from AMANDA
  • 2001
  • In: International Journal of Modern Physics A. - 0217-751X .- 1793-656X. ; 16:1C, s. 1013-1015
  • Journal article (peer-reviewed)abstract
    • We present results based on data taken in 1997 with the 302-PMT Antarctic Muon and Neutrino Detector Array-B10 ("AMANDA-B10") array. Atmospheric neutrinos created in the northern hemisphere are observed indirectly through their charged current interactions which produce relativistic, Cherenkov-light-emitting upgoing muons in the South Pole ice cap. The reconstructed angular distribution of these events is in good agreement with expectation and demonstrates the viability of this ice-based device as a neutrino telescope.
  •  
42.
  • Ahmed, M., et al. (author)
  • Search for the lepton-family-number nonconserving decay μ +→e +γ
  • 2002
  • In: Physical Review D. - : American Physical Society. - 1550-7998 .- 1550-2368. ; 65:11
  • Journal article (peer-reviewed)abstract
    • The MEGA experiment, which searched for the muon- and electron-number violating decay μ +→e + γ, is described. The spectrometer system, the calibrations, the data taking procedures, the data analysis, and the sensitivity of the experiment are discussed. The most stringent upper limit on the branching ratio, B(μ + →e + γ)<1.2×10 -11 with 90% confidence, is derived from a likelihood analysis.
  •  
43.
  • Ahrens, J., et al. (author)
  • Calibration and survey of AMANDA with the SPASE detectors
  • 2004
  • In: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier. - 0168-9002 .- 1872-9576. ; 522:3, s. 347-359
  • Journal article (peer-reviewed)abstract
    • We report on the analysis of air showers observed in coincidence by the Antarctic Muon and Neutrino detector array (AMANDA-B10) and the South Pole Air Shower Experiment (SPASE-1 and SPASE-2). We discuss the use of coincident events for calibration and survey of the deep AMANDA detector as well as the response of AMANDA to muon bundles. This analysis uses data taken during 1997 when both SPASE-1 and SPASE-2 were in operation to provide a stereo view of AMANDA. © 2003 Elsevier B.V. All rights reserved.
  •  
44.
  • Ahrens, J., et al. (author)
  • Measurement of the cosmic ray composition at the knee with the SPASE-2/AMANDA-B10 detectors
  • 2004
  • In: Astroparticle physics. - : Elsevier. - 0927-6505 .- 1873-2852. ; 21:6, s. 565-581
  • Journal article (peer-reviewed)abstract
    • The mass composition of high-energy cosmic rays at energies above 1015 eV can provide crucial information for the understanding of their origin. Air showers were measured simultaneously with the SPASE-2 air shower array and the AMANDA-B10 Cherenkov telescope at the South Pole. This combination has the advantage to sample almost all high-energy shower muons and is thus a new approach to the determination of the cosmic ray composition. The change in the cosmic ray mass composition was measured versus existing data from direct measurements at low energies. Our data show an increase of the mean log atomic mass 〈lnA〉 by about 0.8 between 500 TeV and 5 PeV. This trend of an increasing mass through the "knee" region is robust against a variety of systematic effects. © 2004 Elsevier B.V. All rights reserved.
  •  
45.
  • Ahrens, J., et al. (author)
  • Search for supernova neutrino bursts with the AMANDA detector
  • 2001
  • In: Astroparticle physics. - : Elsevier. - 0927-6505 .- 1873-2852. ; 16:4, s. 345-359
  • Journal article (peer-reviewed)abstract
    • The core collapse of a massive star in the Milky Way will produce a neutrino burst, intense enough to be detected by existing underground detectors. The AMANDA neutrino telescope located deep in the South Pole ice can detect MeV neutrinos by a collective rate increase in all photo-multipliers on top of dark noise. The main source of light comes from positrons produced in the CC reaction of anti-electron neutrinos on free protons ve + p → e+ + n. This paper describes the first supernova search performed on the full sets of data taken during 1997 and 1998 (215 days of live time) with 302 of the detector's optical modules. No candidate events resulted from this search. The performance of the detector is calculated, yielding a 70% coverage of the galaxy with one background fake per year with 90% efficiency for the detector configuration under study. An upper limit at the 90% c.l. on the rate of stellar collapses in the Milky Way is derived, yielding 4.3 events per year. A trigger algorithm is presented and its performance estimated. Possible improvements of the detector hardware are reviewed.
  •  
46.
  •  
47.
  • Karle, A., et al. (author)
  • Observation of high energy atmospheric neutrinos with AMANDA
  • 2000
  • In: AIP Conference Proceedings. - : American Institute of Physics (AIP). ; , s. 823-827
  • Conference paper (peer-reviewed)abstract
    • In 1997 the Antarctic Muon and Neutrino Detector Array (AMANDA) started operating with 10 strings. In an analysis of data taken during the first year of operation 188 atmospheric neutrino candidates were found. Their zenith angle distribution agrees with expectations based on Monte Carlo simulations. A preliminary upper limit is given on a diffuse flux of high energy neutrinos of astrophysical origin.
  •  
48.
  • Kowalski, Marek, et al. (author)
  • Physics results from the AMANDA neutrino detector
  • 2001
  • In: Proceedings of Science. - 1824-8039. ; HEP2001
  • Journal article (peer-reviewed)abstract
    • In the winter season of 2000, the AMANDA (Antarctic Muon And NeutrinoDetector Array) detector was completed to its nal state. We report on major physicsresults obtained from the AMANDA-B10 detector, as well as initial results of the fullAMANDA-II detector.
  •  
49.
  • Ahrens, J., et al. (author)
  • Limits on diffuse fluxes of high energy extraterrestrial neutrinos with the AMANDA-B10 detector
  • 2003
  • In: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 90:25, s. 2511011-2511015
  • Journal article (peer-reviewed)abstract
    • A report on the limits, which could be placed on diffuse fluxes of high energy extraterrestrial neutrinos, was presented. The incorporation of neutrino oscillations was necessary for interpreting the limits in terms of the flux from a cosmological distributions of sources. The energetic accelerated environments were presented as the sources of high energy extraterrestrial neutrinos.
  •  
50.
  • Ahrens, J., et al. (author)
  • Search for point sources of high-energy neutrinos with AMANDA
  • 2003
  • In: Astrophysical Journal Letters. - : Institute of Physics (IOP). - 2041-8205 .- 0004-637X .- 1538-4357. ; 583:2 I, s. 1040-1057
  • Journal article (peer-reviewed)abstract
    • This paper describes the search for astronomical sources of high-energy neutrinos using the AMANDA-B10 detector, an array of 302 photomultiplier tubes used for the detection of Cerenkov light from upward-traveling neutrino-induced muons, buried deep in ice at the South Pole. The absolute pointing accuracy and angular resolution were studied by using coincident events between the AMANDA detector and two independent telescopes on the surface, the GASP air Cerenkov telescope and the SPASE extensive air shower array. Using data collected from 1997 April to October (130.1 days of live time), a general survey of the northern hemisphere revealed no statistically significant excess of events from any direction. The sensitivity for a flux of muon neutrinos is based on the effective detection area for through-going muons. Averaged over the northern sky, the effective detection area exceeds 10,000 m2 for E μ ≈ 10 TeV. Neutrinos generated in the atmosphere by cosmic-ray interactions were used to verify the predicted performance of the detector. For a source with a differential energy spectrum proportional to Eν -2 and declination larger than +40°, we obtain E2(dNν/dE) ≤ 10-6 GeV cm-2 s-1 for an energy threshold of 10 GeV.
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