S. I. Sinegovsky

Atmospheric muon flux at sea level, underground, and underwater

The vertical sea-level muon spectrum at energies above 1 GeV and the muon intensities at depths up to 18 km w.e. in different rocks and in water are calculated. The results are particularly collated with a great body of the ground-level, underground, and underwater muon data. In the hadron-cascade calculations, we take into account the logarithmic growth with energy of inelastic cross sections and pion, kaon, and nucleon generation in pion-nucleus collisions. For evaluating the prompt-muon contribution to the muon flux, we apply the two phenomenological approaches to the charm production problem: the recombination quark-parton model and the quark-gluon string model. To solve the muon transport equation at large depths of a homogeneous medium, we used a semianalytical method, which allows the inclusion of an arbitrary ~decreasing! muon spectrum at the medium boundary and real energy dependence of both continuous and discrete muon energy losses. The method is checked for accuracy by direct Monte Carlo calculation. Whenever possible, we give simple fitting formulas describing our numerical results. @S0556-2821~98!00313-0# PACS number~s!: 13.85.Tp, 96.40.Tv

Prompt leptons in cosmic rays

SummaryEnergy spectra and zenith-angle distributions of cosmic-ray muons, neutrinos and antineutrinos of prompt generation for energy interval (1÷106) TeV are calculated. For calculations of differential cross-sections of D±, D0,

High-energy neutrino fluxes and flavor ratio in the Earth’s atmosphere

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Meson Cascade in the Atmosphere, Uncertainties in Calculating the Fluxes of High-Energy Muons, and Data of Direct Measurements

0 and Λc production inNN and πN interactions the recombination quark-parton model (RQPM) is used. Accounting of nuclear effects is done by using the additive quark model and the optical model of nucleus. Detailed comparison of results obtained in RQPM with corresponding predictions of quark-gluon string model (MQGS) is carried out. Dynamics of semi-leptonic D- and Λc and energy losses of muons in the atmosphere are taken into account. Calculations of hadronic cascades in the atmosphere are done with accounting of growth with energy of total inelastic hadron-nucleus cross-sections, steepening of primary cosmic-ray spectrum and processes of pion regeneration. The comparison of our calculations with experimental data and with calculations of other authors is given.

High-energy cosmic ray muons in the Earth`s atmosphere

We present high energy spectra and zenith-angle distributions of the atmospheric muons computed for the depths of the locations of the underwater neutrino telescopes. We compare the calculations with the data obtained in the Baikal and the AMANDA muon experiments. The prompt muon contribution to the muon flux underwater due to recent perturbative QCD-based models of the charm production is expected to be observable at the depths of the large underwater neutrino telescopes. This appears to be probable even at rather shallow depths ~1‐2 km!, provided the energy threshold for muon detection is raised above ;100 TeV.

High-energy spectrum and zenith-angle distribution of atmospheric neutrinos

We calculate the atmospheric neutrino fluxes in the energy range 100 GeV – 10 PeV with the use of several known hadronic models and a few parametrizations of the cosmic ray spectra which take into account the knee. The calculations are compared with the atmospheric neutrino measurements by Frejus, AMANDA, IceCube and ANTARES. An analytic description is presented for the conventional (�µ + ¯ �µ) and (�e + ¯e) energy spectra, averaged over zenith angles, which can be used to obtain test data of the neutrino event reconstruction in neutrino telescopes. The sum of the calculated atmospheric �µ flux and the IceCube best-fit astrophysical flux gives the evidently higher flux as compared to the IceCube59 data, giving rise the question concerning the hypothesis of the equal flavor composition of the high-energy astrophysical neutrino flux. Calculations show that the transition from the atmospheric electron neutrino flux to the predominance of the astrophysical neutrinos occurs at 30 100 TeV if the prompt neutrino component is taken into consideration. The neutrino flavor ratio, extracted from the IceCube data, does not reveal the trend to increase with the energy as is expected for the conventional neutrino flux in the energy range 100 GeV – 30 TeV. A depression of the ratio R�µ/�e possibly indicates that the atmospheric electron neutrino flux obtained in the IceCube experiment contains an admixture of the astrophysical neutrinos in the range 10 50 TeV.

High-energy spectra of atmospheric neutrinos

The prompt muon contribution to the deep-sea atmospheric muon flux can serve as a tool for probing into the small-x feature of the gluon density inside of a nucleon, if the muon energy threshold could be lifted to 100 TeV. The prompt muon flux underwater is calculated taking into consideration predictions of recent charm production models in which the small-x behaviour of the gluon distribution is probed. We discuss the possibility of distinguishing the PQCD models of the charm production differing in the small-x exponent of the gluon distribution, in measurements of the muon flux at energies 10–100 TeV with neutrino telescopes.

Potential of deep-underwater neutrino telescopes for recording muons from charm decay

A new calculation of the atmospheric fluxes of cosmic-ray hadrons and muons in the energy range 10–104 GeV is performed on the basis of the method for solving nuclear-cascade equations with allowance for a nonscaling behavior of inclusive hadron-production cross sections, the growth of cross sections for inelastic hadron-nucleus collisions with increasing energy, and a non-power-law character of the primary spectrum. The fluxes of secondary cosmic rays at various levels in the atmosphere are calculated for three models of the spectrum and composition of primary cosmic rays. The effect of uncertainties in the spectrumand composition of primary cosmic rays on the flux of atmosphericmuons and their charge ratio at sea level is investigated. The calculated energy spectra of muons at sea level are compared with the results of previous experiments and the results of recent measurements performed by means of the L3 + Cosmic and CosmoALEPH spectrometers, as well as with the results of other calculations.