152 research outputs found
Shape of primary proton spectrum in multi-TeV region from data on vertical muon flux
It is shown, that primary proton spectrum, reconstructed from sea-level and
underground data on muon spectrum with the use of QGSJET 01, QGSJET II, NEXUS
3.97 and SIBYLL 2.1 interaction models, demonstrates not only model-dependent
intensity, but also model-dependent form. For correct reproduction of muon
spectrum shape primary proton flux should have non-constant power index for all
considered models, except SIBYLL 2.1, with break at energies around 10-15 TeV
and value of exponent before break close to that obtained in ATIC-2 experiment.
To validate presence of this break understanding of inclusive spectra behavior
in fragmentation region in p-air collisions should be improved, but we show,
that it is impossible to do on the basis of the existing experimental data on
primary nuclei, atmospheric muon and hadron fluxes.Comment: Submitted to Phys. Rev.
PHYSICAL SIMULATION OF COLD ROLLING OF ULTRA-FINE GRAINED AL 5083 ALLOY TO STUDY MICROSTRUCTURE EVOLUTION
Abstract. Recent investigations have demonstrated that ultra-fine grained (UFG) Al 5xxx alloys have a significant potential for industrial applications due to their enhanced mechanical and functional properties. The Al 5xxx alloys often have to undergo hot/cold rolling metalforming operations for fabrication of near-net shape products since they are widely used in form of sheets in marine, transport, and chemical engineering. The development of hot/cold rolling routes for the UFG metallic materials are very expensive due to much higher cost of the UFG metallic materials and time consuming due to numerous experimental trials. The objective of this work is to perform physical simulation of cold rolling of the UFG Al 5083 alloy obtained via equal channel angular pressing with parallel channels and to analyze the effect of cold rolling on the microstucture and microhardness of the material. It is demonstrated that physical simulation of metalforming processes for the UFG metallic materials can significantly reduce the amount of material required for development of processing routes and increase the efficiency of experimental work
Atmospheric muon flux at PeV energies
In the near future the energy region above few hundreds of TeV may really be
accessible for measurements of the atmospheric muon spectrum by the IceCube
array. Therefore one expects that muon flux uncertainties above 50 TeV, related
to a poor knowledge of charm production cross sections and insufficiently
examined primary spectra and composition, will be diminished. We give
predictions for the very high-energy muon spectrum at sea level, obtained with
the three hadronic interaction models, taking into account also the muon
contribution due to decays of the charmed hadrons.Comment: 8 pages, 3 figures. The version published in Int. J. Mod. Phys.
Muon-Induced Background Study for Underground Laboratories
We provide a comprehensive study of the cosmic-ray muon flux and induced
activity as a function of overburden along with a convenient parameterization
of the salient fluxes and differential distributions for a suite of underground
laboratories ranging in depth from 1 to 8 km.w.e.. Particular attention
is given to the muon-induced fast neutron activity for the underground sites
and we develop a Depth-Sensitivity-Relation to characterize the effect of such
background in experiments searching for WIMP dark matter and neutrinoless
double beta decay.Comment: 18 pages, 28 figure
Neutron production by cosmic-ray muons at shallow depth
The yield of neutrons produced by cosmic ray muons at a shallow depth of 32
meters of water equivalent has been measured. The Palo Verde neutrino detector,
containing 11.3 tons of Gd loaded liquid scintillator and 3.5 tons of acrylic
served as a target. The rate of one and two neutron captures was determined.
Modeling the neutron capture efficiency allowed us to deduce the total yield of
neutrons neutrons per muon
and g/cm. This yield is consistent with previous measurements at similar
depths.Comment: 12 pages, 3 figure
Muon `Depth -- Intensity' Relation Measured by LVD Underground Experiment and Cosmic-Ray Muon Spectrum at Sea Level
We present the analysis of the muon events with all muon multiplicities
collected during 21804 hours of operation of the first LVD tower. The measured
angular distribution of muon intensity has been converted to the `depth --
vertical intensity' relation in the depth range from 3 to 12 km w.e.. The
analysis of this relation allowed to derive the power index, , of the
primary all-nucleon spectrum: . The `depth -- vertical
intensity' relation has been converted to standard rock and the comparison with
the data of other experiments has been done. We present also the derived
vertical muon spectrum at sea level.Comment: 7 pages, 3 figures, to be published on Phys. Rev.
Production of Radioactive Isotopes through Cosmic Muon Spallation in KamLAND
Radioactive isotopes produced through cosmic muon spallation are a background
for rare-event detection in detectors, double--decay experiments,
and dark-matter searches. Understanding the nature of cosmogenic backgrounds is
particularly important for future experiments aiming to determine the pep and
CNO solar neutrino fluxes, for which the background is dominated by the
spallation production of C. Data from the Kamioka liquid-scintillator
antineutrino detector (KamLAND) provides valuable information for better
understanding these backgrounds, especially in liquid scintillators, and for
checking estimates from current simulations based upon MUSIC, FLUKA, and
GEANT4. Using the time correlation between detected muons and neutron captures,
the neutron production yield in the KamLAND liquid scintillator is measured to
be . For other isotopes,
the production yield is determined from the observed time correlation related
to known isotope lifetimes. We find some yields are inconsistent with
extrapolations based on an accelerator muon beam experiment.Comment: 16 pages, 20 figure
Study of single muons with the Large Volume Detector at Gran Sasso Laboratory
The present study is based on the sample of about 3 mln single muons observed
by LVD at underground Gran Sasso Laboratory during 36500 live hours from June
1992 to February 1998. We have measured the muon intensity at slant depths from
3 km w.e. to 20 km w.e. Most events are high energy downward muons produced by
meson decay in the atmosphere. The analysis of these muons has revealed the
power index of pion and kaon spectrum: 2.76 \pm 0.05. The reminders are
horizontal muons produced by the neutrino interactions in the rock surrounding
LVD. The value of this flux is obtained. The results are compared with Monte
Carlo simulations and the world data.Comment: 13 pages, 2 figures, accepted for publication in "Physics of Atomic
Nuclei
Upper Limit on the Prompt Muon Flux Derived from the LVD Underground Experiment
We present the analysis of the muon events with all muon multiplicities
collected during 21804 hours of operation of the first LVD tower. The measured
depth-angular distribution of muon intensities has been used to obtain the
normalization factor, A, the power index, gamma, of the primary all-nucleon
spectrum and the ratio, R_c, of prompt muon flux to that of pi-mesons - the
main parameters which determine the spectrum of cosmic ray muons at the sea
level. The value of gamma = 2.77 +/- 0.05 (68% C.L.) and R_c < 2.0 x 10^-3 (95%
C.L.) have been obtained. The upper limit to the prompt muon flux favours the
models of charm production based on QGSM and the dual parton model.Comment: 10 pages, 4 figures, RevTex. To appear in Phys. Rev.
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