487,593 research outputs found
Atmospheric Lepton Fluxes
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 and are discussed, along with the implications
of the muon charge ratio for the 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
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
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 and 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 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
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 m 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
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
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
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
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 -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 -ray rates into
-ray fluxes. A good agreement between the measured and simulated
-ray fluxes is achieved with the knowledge of the chemical composition
and radioactivity levels in the rock. The neutron fluxes and -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
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
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