Browsing by Author "Fedynitch, Anatoli"
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- A state-of-the-art calculation of atmospheric lepton fluxesPublication . Fedynitch, Anatoli; Dembinski, Hans; Engel, Ralph; Gaisser, Thomas K.; Riehn, Felix; Stanev, TodorAtmospheric leptons are of continuous interest for several scientific communities. At low and intermediate energies, atmospheric neutrinos are the signal for studies of fundamental neutrino properties and at high energies, they constitute the background for the characterization of the features of the astrophysical neutrino flux. We have studied in depth the relation between observable inclusive lepton fluxes/ratios and hadronic interactions by using a novel numerical transport equation solver MCEq. It enables us to characterize, with an unprecedented precision, relevant particle interaction energies, important hadron species, and the secondary particle production phase-space in terms of typical accelerator observables. Based on our findings, we improved existing interaction models S IBYLL and D PMJET and created an efficient scheme to propagate correlated model uncertainties into derived lepton fluxes. We present state-of-the-art calculations of inclusive lepton fluxes and discuss possible directions towards reducing uncertainties below 10%.
- Data-driven model of the cosmic-ray flux and mass composition from 10 GeV to $10^{11}$ GeVPublication . Dembinski, Hans Peter; Engel, Ralph; Fedynitch, Anatoli; Gaisser, Thomas; Riehn, Felix; Stanev, TodorWe present a new parametrization of the cosmic-ray flux and its mass composition over an energy range from 10 GeV to $10^{11}$ GeV. Our approach is data-driven and relies on theoretical assumptions as little as possible. We combine measurements of the flux of individual elements from high-precision satellites and balloon experiments with indirect measurements of mass groups from the leading air shower experiments. To our knowledge, we provide the first fit of this kind that consistently takes both statistical and systematic uncertainties into account. The uncertainty on the energy scales of individual experiments is handled explicitly in our mathematical approach. Part of our results is a common energy scale and adjustment factors for the energy scales of the participating experiments. Our fit has a reduced $\chi^2$-value of 0.5, showing that experimental data are in good agreement, if systematic uncertainties are considered. Our model may serve as a world-average of the measured fluxes for individual elements from proton to iron from 10 GeV to $10^{11}$ GeV. It is useful as an input for simulations or theoretical computations based on cosmic rays. The experimental uncertainties of the input data are captured in a covariance matrix, which can be propagated into derived quantities.
- The hadronic interaction model Sibyll – past, present and futurePublication . Engel, Ralph; Riehn, Felix; Fedynitch, Anatoli; Gaisser, Thomas K.; Stanev, TodorSibyll is one of the first microscopic interaction models that was specifically developed for interpreting cosmic ray data. It combines non-perturbative concepts of simulating hadronic particle production with predictions derived from perturbative QCD calculations, focusing on forward particle production of relevance in studying cosmic ray interactions. In this contribution we briefly recall the history of Sibyll and then, in this context, describe improvements made in the different versions of the Sibyll model. The discussion focuses on the basic concepts and ideas of these improvements rather than going into detail or giving a comprehensive description of the models. We also discuss shortcomings, conceptual problems, and uncertainties in modeling hadronic interactions and make some suggestions how to address these open questions in the future.
- The hadronic interaction model SIBYLL 2.3c and Feynman scalingPublication . Riehn, Felix; Dembinski, Hans P.; Engel, Ralph; Fedynitch, Anatoli; Gaisser, Thomas K.; Stanev, TodorThe Monte Carlo model Sibyll has been designed for efficient simulation of hadronic multiparticle production up to the highest energies as needed for interpreting cosmic ray measurements. For more than 15 years, version 2.1 of Sibyll has been one of the standard models for air shower simulation. Motivated by data of LHC and fixed-target experiments and a better understanding of the phenomenology of hadronic interactions, we have developed an improved version of this model, version 2.3, which has been released in 2016. In this contribution we present a revised version of this model, called Sibyll 2.3c, that is further improved by adjusting particle production spectra to match the expectation of Feynman scaling in the fragmentation region. After a brief introduction to the changes implemented in Sibyll 2.3 and 2.3c with respect to Sibyll 2.1, the current predictions of the model for the depth of shower maximum, the number of muons at ground, and the energy spectrum of muons in extensive air showers are presented.