scholarly journals Cosmic-ray acceleration at collisionless astrophysical shocks using Monte-Carlo simulations

2015 ◽  
Vol 580 ◽  
pp. A58 ◽  
Author(s):  
M. Wolff ◽  
R. C. Tautz
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Cosmic Ray ◽  
Cosmic Ray Acceleration ◽  
Astrophysical Shocks

scholarly journals Monte Carlo Simulations of Particle Acceleration at Oblique Shocks

1994 ◽  
Vol 142 ◽  
pp. 547-552
Author(s):  
Matthew G. Baring ◽  
Donald C. Ellison ◽  
Frank C. Jones
Keyword(s):  
Monte Carlo ◽  
Mach Number ◽  
Cosmic Rays ◽  
Monte Carlo Simulations ◽  
Cosmic Ray ◽  
Heavy Ion ◽  
High Energy ◽  
Shock Acceleration ◽  
High Energy Cosmic Rays ◽  
Cosmic Ray Acceleration

AbstractThe Fermi shock acceleration mechanism may be responsible for the production of high-energy cosmic rays in a wide variety of environments. Modeling of this phenomenon has largely focused on plane-parallel shocks, and one of the most promising techniques for its study is the Monte Carlo simulation of particle transport in shocked fluid flows. One of the principal problems in shock acceleration theory is the mechanism and efficiency of injection of particles from the thermal gas into the accelerated population. The Monte Carlo technique is ideally suited to addressing the injection problem directly, and previous applications of it to the quasi-parallel Earth bow shock led to very successful modeling of proton and heavy ion spectra, as well as other observed quantities. Recently this technique has been extended to oblique shock geometries, in which the upstream magnetic field makes a significant angle ΘB1 to the shock normal. In this paper, spectral results from test particle Monte Carlo simulations of cosmic-ray acceleration at oblique, nonrelativistic shocks are presented. The results show that low Mach number shocks have injection efficiencies that are relatively insensitive to (though not independent of) the shock obliquity, but that there is a dramatic drop in efficiency for shocks of Mach number 30 or more as the obliquity increases above 15°. Cosmic-ray distributions just upstream of the shock reveal prominent bumps at energies below the thermal peak; these disappear far upstream but might be observable features close to astrophysical shocks.Subject headings: acceleration of particles — cosmic rays — shock waves

scholarly journals Soil Moisture and Air Humidity Dependence of the Above-Ground Cosmic-Ray Neutron Intensity

2021 ◽  
Vol 2 ◽  
Author(s):  
Markus Köhli ◽  
Jannis Weimar ◽  
Martin Schrön ◽  
Roland Baatz ◽  
Ulrich Schmidt
Keyword(s):  
Monte Carlo ◽  
Soil Moisture ◽  
Monte Carlo Simulations ◽  
Count Rate ◽  
Neutron Transport ◽  
Cosmic Ray ◽  
Mathematical Treatment ◽  
Specific Response ◽  
Air Humidity ◽  
Parameter Equation

Investigations of neutron transport through air and soil by Monte Carlo simulations led to major advancements toward a precise interpretation of measurements; they particularly improved the understanding of the cosmic-ray neutron footprint. Up to now, the conversion of soil moisture to a detectable neutron count rate has relied mainly on the equation presented by Desilets and Zreda in 2010. While in general a hyperbolic expression can be derived from theoretical considerations, their empiric parameterization needs to be revised for two reasons. Firstly, a rigorous mathematical treatment reveals that the values of the four parameters are ambiguous because their values are not independent. We found a three-parameter equation with unambiguous values of the parameters that is equivalent in any other respect to the four-parameter equation. Secondly, high-resolution Monte-Carlo simulations revealed a systematic deviation of the count rate to soil moisture relation especially for extremely dry conditions as well as very humid conditions. That is a hint that a smaller contribution to the intensity was forgotten or not adequately treated by the conventional approach. Investigating the above-ground neutron flux through a broadly based Monte-Carlo simulation campaign revealed a more detailed understanding of different contributions to this signal, especially targeting air humidity corrections. The packages MCNP and URANOS were used to derive a function able to describe the respective dependencies, including the effect of different hydrogen pools and the detector-specific response function. The new relationship has been tested at two exemplary measurement sites, and its remarkable performance allows for a promising prospect of more comprehensive data quality in the future.

scholarly journals Muon Measurements with IceTop

2019 ◽  
Vol 208 ◽  
pp. 03003 ◽  
Author(s):  
Javier G. Gonzalez
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Cosmic Ray ◽  
Shower Axis ◽  
South Pole ◽  
Air Showers ◽  
Hadronic Interaction ◽  
Interaction Models ◽  
Lateral Distance ◽  
Cosmic Ray Flux

We present the measurement of the density of GeV muons in near-vertical air showers by the IceTop array at the South Pole. The muon density is measured at 600 m and 800 m lateral distance from the shower axis in air showers between 1 PeV and 100 PeV. This result can be used to constrain hadronic interaction models by comparing it with the outcome of Monte Carlo simulations. We show that some models do not produce muon densities in agreement with this result unless an unphysical composition of the primary cosmic ray flux is assumed.

Monte Carlo Simulations for Changes in the Cosmic-ray Flux on the Earth's Surface Due to Heavy-Metal Pollution in the Atmosphere

2011 ◽  
Vol 61 (8) ◽  
pp. 727-733
Author(s):  
Jaw Won SHIN ◽  
Tae-Sun PARK ◽  
Seung-Woo HONG* ◽  
Oubong GWUN ◽  
Chong Yeal KIM
Keyword(s):  
Heavy Metal ◽  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Metal Pollution ◽  
Heavy Metal Pollution ◽  
Cosmic Ray ◽  
Cosmic Ray Flux

scholarly journals Determination of cosmic-ray primary mass on an event-by-event basis using radio detection

2019 ◽  
Vol 216 ◽  
pp. 02005
Author(s):  
Washington Carvalho ◽  
Jaime Alvarez-Muñiz
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Cosmic Ray ◽  
Primary Mass ◽  
Radio Detection ◽  
Shower Development ◽  
Radio Signals ◽  
Event Basis

Traditionally, the depth of maximum shower development Xmax has been used as a surrogate observable for composition. Here we present the possibility of a new methodology to discriminate between light and heavy cosmic-ray primaries on an event-by-event basis. This method is based on comparisons between detected radio signals and Monte Carlo simulations, but instead of first reconstructing Xmax, we try to infer the cosmic-ray composition directly. We show that a large discrimination efficiency could in principle be reached for zenith angles above θ≃65°, even when some of the typical uncertainties in radio detection are taken into account.

Particle acceleration at forward and reverse shocks in SNRs

2018 ◽  
Vol 27 (10) ◽  
pp. 1844023 ◽  
Author(s):  
Vladimir Zirakashvili
Keyword(s):  
Supernova Remnants ◽  
Gamma Ray ◽  
Cosmic Ray ◽  
High Energy ◽  
Field Amplification ◽  
Streaming Instability ◽  
Cosmic Ray Acceleration ◽  
Astrophysical Neutrinos ◽  
Astrophysical Shocks ◽  
Accelerated Particles

Cosmic ray acceleration by astrophysical shocks in supernova remnants is briefly reviewed. Results of numerical modeling taking into account the magnetic field amplification by streaming instability and the shock modification are presented. Nonthermal emission produced by accelerated particles in old supernova remnants is compared with available data of modern radio, X-ray and gamma-ray astronomies. It is also shown that high-energy neutrinos produced in young supernova remnants of Type IIn extragalactic supernova can explain the recent IceCube detection of astrophysical neutrinos.

DOES THE "KNEE" IN PRIMARY COSMIC RAY SPECTRUM EXIST?

2003 ◽  
Vol 18 (18) ◽  
pp. 1225-1234 ◽  
Author(s):  
YURI V. STENKIN
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Power Law ◽  
Cosmic Ray ◽  
New Physics ◽  
Point Of View ◽  
Experimental Point ◽  
Primary Spectrum ◽  
Hadronic Structure ◽  
Knee Problem

The problem of the knee in primary cosmic ray at energy about 3–5 PeV is the most exciting problem in cosmic ray physics. Since 1958, physicists have been trying to solve this problem. In our opinion, the problem could be solved from the experimental point of view, whereas the primary spectrum would follow a pure power law. A key to the "knee" problem lies in the hadronic structure of EAS and its propagation in the Earth's atmosphere. Neither exotic processes nor new physics are used. An explanation of the approach and some results of Monte Carlo simulations are given below.

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