487,593 research outputs found

    Atmospheric Lepton Fluxes

    Full text link
    This review of atmospheric muons and neutrinos emphasizes the high energy range relevant for backgrounds to high-energy neutrinos of astrophysical origin. After a brief historical introduction, the main distinguishing features of atmospheric νμ\nu_\mu and νe\nu_e are discussed, along with the implications of the muon charge ratio for the νμ/νˉμ\nu_\mu/\bar{\nu}_\mu ratio. Methods to account for effects of the knee in the primary cosmic-ray spectrum and the energy-dependence of hadronic interactions on the neutrino fluxes are discussed and illustrated in the context of recent results from IceCube. A simple numerical/analytic method is proposed for systematic investigation of uncertainties in neutrino fluxes arising from uncertainties in the primary cosmic-ray spectrum/composition and hadronic interactions.Comment: 8 pages, 6 figures, for Proceedings of ISVHECRI 2014 This revised version corrects a typo in Eq. 11. There are no changes in the results (the typo was only in the LaTeX, not in the code

    Atmospheric Neutrino Fluxes

    Get PDF
    This talk is a status report on calculations of the flux of atmospheric neutrinos from the sub-GeV range to E_\nu ~ PeV. In the lower energy range (E_\nu < 1 TeV) the primary interest is in using the atmospheric neutrino beam to study neutrino oscillations. In the TeV range and above, atmospheric neutrinos are a calibration source and background for neutrino telescopes.Comment: 9 pages, 10 figures, for Proceedings of Neutrino 200

    Center vortices as composites of monopole fluxes

    Full text link
    We study the relation between the flux of a center vortex obtained from the center vortex model and the flux formed between monopoles obtained from the Abelian gauge fixing method. Motivated by the Monte Carlo simulations which have shown that almost all monopoles are sitting on the top of vortices, we construct the fluxes of center vortices for SU(2)SU(2) and SU(3)SU(3) gauge groups using fractional fluxes of monopoles. Then, we compute the potentials in the fundamental representation induced by center vortices and fractional fluxes of monopoles. We show that by combining the fractional fluxes of monopoles one can produce the center vortex fluxes for SU(3)SU(3) gauge group in a "center vortex model". Comparing the potentials, we conclude that the fractional fluxes of monopoles attract each other.Comment: 7 pages, 6 figures, Contribution to the conference "Quark Confinement and the Hadron Spectrum XI", Saint Petersburg, Russia, 7-12 Sep 201

    The Spectral Type of the Ionizing Stars and the Infrared Fluxes of HII Regions

    Full text link
    The 20 cm radio continuum fluxes of 91 HII regions in a previously compiled catalog have been determined. The spectral types of the ionizing stars in 42 regions with known distances are estimated. These spectral types range from B0.5 to O7, corresponding to effective temperatures of 29 000-37 000 K. The dependences of the infrared (IR) fluxes at 8, 24, and 160 μ\mum on the 20 cm flux are considered. The IR fluxes are used as a diagnostic of heating of the matter, and the radio fluxes as measurements of the number of ionizing photons. It is established that the IR fluxes grow approximately linearly with the radio flux. This growth of the IR fluxes probably indicates a growth of the mass of heated material in the envelope surrounding the HII region with increasing effective temperature of the star.Comment: 16, pages, 10 figures, published in Astronomy Report

    Atmospheric neutrino flux at INO, South Pole and Pyh\"asalmi

    Get PDF
    We present the calculation of the atmospheric neutrino fluxes for the neutrino experiments proposed at INO, South Pole and Pyh\"asalmi. Neutrino fluxes have been obtained using ATMNC, a simulation code for cosmic ray in the atmosphere. Even using the same primary flux model and the interaction model, the calculated atmospheric neutrino fluxes are different for the different sites due to the geomagnetic field. The prediction of these fluxes in the present paper would be quite useful in the experimental analysis.Comment: 12Pages,9Fig

    Van Allen Probes show that the inner radiation zone contains no MeV electrons: ECT/MagEIS data

    Get PDF
    Abstract We present Van Allen Probe observations of electrons in the inner radiation zone. The measurements were made by the Energetic Particle, Composition, and Thermal Plasma/Magnetic Electron Ion Spectrometer (MagEIS) sensors that were designed to measure electrons with the ability to remove unwanted signals from penetrating protons, providing clean measurements. No electrons \u3e900 keV were observed with equatorial fluxes above background (i.e., \u3e0.1 el/(cm2 s sr keV)) in the inner zone. The observed fluxes are compared to the AE9 model and CRRES observations. Electron fluxes \u3c200 keV exceeded the AE9 model 50% fluxes and were lower than the higher-energy model fluxes. Phase space density radial profiles for 1.3 ≤ L* \u3c 2.5 had mostly positive gradients except near L*~2.1, where the profiles for μ = 20–30 MeV/G were flat or slightly peaked. The major result is that MagEIS data do not show the presence of significant fluxes of MeV electrons in the inner zone while current radiation belt models and previous publications do

    A model measurements comparison of atmospheric forcing and surface fluxes of the Baltic Sea

    Get PDF
    Observed basic meteorological quantities, heat and radiation fluxes from three different measurement stations in the Baltic Sea are compared with model data of the coupled sea-ice-ocean model BSIOM in order to evaluate the atmospheric forcing, corresponding surface fluxes and the sea surface response. Observational data were made available from the BASIS winter campaigns in 1998 and 2001 as well as from the r/v "Alkor" cruise in June 2001. Simulated fluxes were calculated from prescribed atmospheric forcing provided from the SMHI meteorological database and modelled sea surface temperatures. The comparison of these fluxes with observations demonstrates a strong correlation, even though mean differences in sensible heat fluxes range from 4 to 12 W m-2 in winter and -25 W m-2 in the June experiment. Differences in latent heat fluxes range from -10 to 23 W m-2. The short-wave radiation flux used as model forcing is on average 15 W m-2 less than the corresponding observations for the winter experiments and 40 W m-2 for the June experiment. Differences in net long-wave radiation fluxes range from -5 to 12 W m-2 in winter and -62 W m-2 for the June experiment. The correspondence between measured and calculated momentum fluxes is very high, which confirms the usability of our model component for calculating surface winds and wind stresses from the atmospheric surface pressure

    Early Results on Radioactive Background Characterization for Sanford Laboratory and DUSEL Experiments

    Full text link
    Measuring external sources of background for a deep underground laboratory at the Homestake Mine is an important step for the planned low-background experiments. The naturally occurring γ\gamma-ray fluxes at different levels in the Homestake Mine are studied using NaI detectors and Monte Carlo simulations. A simple algorithm is developed to convert the measured γ\gamma-ray rates into γ\gamma-ray fluxes. A good agreement between the measured and simulated γ\gamma-ray fluxes is achieved with the knowledge of the chemical composition and radioactivity levels in the rock. The neutron fluxes and γ\gamma-ray fluxes are predicted by Monte Carlo simulations for different levels including inaccessible levels that are under construction for the planned low background experiments.Comment: 16 pages, 2 figures, and 9 table

    Fluxes in Heterotic and Type II String Compactifications

    Full text link
    In this paper we consider heterotic compactifications on K3 x T2 as well as type II compactifications on K3-fibred Calabi-Yau spaces with certain fluxes for the gauge and RR field strengths F and H turned on. By providing an identification of corresponding fluxes we show that the well-known N=2 heterotic/type II string-string duality still holds for a subset of all possible fluxes, namely those which arise from six-dimensional gauge fields with internal magnetic flux on the common two-sphere P1, which is the base space of the type II K3-fibration. On the other hand, F- and H-fluxes without P1-support, such as heterotic F-fluxes on the torus T2 or type II H-fluxes on cycles of the K3-fibre cannot be matched in any simple way, which is a challenge for heterotic/type II string-string duality. Our analysis is based on the comparison of terms in the effective low-energy heterotic and type II actions which are induced by the fluxes, such as the Green-Schwarz couplings related to flux-induced U(1) anomalies, the effective superpotential and the Fayet-Iliopoulos scalar potential.Comment: 27 pages, latex, replaced version with additional ref
    corecore