Search Publications
Fast and accurate evaluation of deep-space galactic cosmic ray fluxes with HelMod-4/CUDA
Gervasi, M.; Rancoita, P. G.; Boschini, M. J. +4 more
The accurate knowledge of cosmic ion fluxes is essential for fundamental physics, deep space missions, and exploration activities in the solar system. In the HelMod-4 model the Parker transport equation is solved using a Monte Carlo approach to evaluate the solar modulation effect on local interstellar spectra of Galactic Cosmic Rays (GCRs). This …
Towards understanding time variations of proton to helium ratios in the heliosphere: Implication for the time dependence of the elements of the diffusion tensor
Potgieter, M. S.; Aslam, O. P. M.; Ngobeni, M. D.
A comprehensive three-dimensional numerical model for the modulation of cosmic rays in the heliosphere is applied to investigate the relative roles of the time dependence of the elements of the diffusion tensor on the proton to total Helium (p/He) and Helium-3 to Helium-4 (3He2/4He2) ratios at rigidities…
The transport of galactic cosmic rays in heliosphere: The HELMOD model compared with other commonly employed solar modulation models
Gervasi, M.; Rancoita, P. G.; Boschini, M. J. +2 more
HELMOD model allows one to describe how solar modulation affects the propagation of galactic cosmic rays (GCRs) through the heliosphere by solving the Parker transport equation. HELMOD provides modulated spectra for protons and nuclei during high and low solar activity periods, in the inner and outer heliosphere, at Earth location and outside the …
A detailed comparison of techniques used to model drift in numerical cosmic ray modulation models
Ferreira, S. E. S.; Engelbrecht, N. Eugene; Mohlolo, S. T.
Drifts have long been known to play a significant role in the transport and modulation of galactic cosmic rays (GCRs), occurring due to gradients in, as well as the curvature of, the heliospheric magnetic field (HMF). GCRs also drift along the wavy current sheet, a structure separating regions of opposite HMF polarity. Furthermore, the influence o…
Galactic cosmic ray transport in inner heliosphere: Study with ion chamber and neutron monitor data for 1936-2006
Modzelewska, R.; Ahluwalia, H. S.; Gololobov, P. Yu.
Galactic cosmic ray (GCR) solar diurnal variation data recorded by shielded ion chambers at Cheltenham/Fredericksburg (CH-IC) and Yakutsk (Yak-IC) are corrected for diurnal temperature variation in upper atmosphere and used to calculate the ratio α of GCR free paths normal (λ⊥) and parallel (λ||) to mean interplanetary magnetic field (I…
Google dataset search and DOI for data in the ESA space science archives
De Marchi, Guido; Masson, Arnaud; Merin, Bruno +3 more
Reproducibility is at the core of science. For this reason, a common practice for authors is to provide links to the data used in their manuscripts upon submission to peer-reviewed journals. In space science, reference to archives' websites of major data providers like space agencies are still accepted by most journals. However, even these website…
Quasi-periodic ripples in the heliosphere from 1 to 40 AU
Birch, M. J.; Hargreaves, J. K.
This study extends the investigation of the ripples in the solar wind and the interplanetary magnetic field at L1 reported by Birch and Hargreaves (2020) to cover heliospheric distances from 1 to 40 AU, using data from the Voyager 2, Ulysses, Juno, Cassini, Themis and Apollo-12 spacecraft. The ripples were extracted from the source data using a ba…
Statistical analysis of solar wind parameter variation with heliospheric distance: Ulysses observations in the ecliptic plane
Bolzan, M. J. A.; Echer, E.; Franco, A. M. S.
The interplanetary magnetic field magnitude Bo, proton density Np and solar wind speed Vsw data from Ulysses spacecraft during its interplanetary cruise interval from Earth to Jupiter, from 18 November 1990 to 31 January 1992, are analyzed in this study. Statistical and wavelet techniques are employed to characteri…
Numerical integration of stochastic differential equations: A parallel cosmic ray modulation implementation on Africa's fastest computer
Moeketsi, D. M.; Engelbrecht, N. E.; Strauss, R. D. +2 more
Three-dimensional studies of the transport and modulation of cosmic ray particles in turbulent astrospheres require large-scale simulations using specialized scientific codes. Essentially, a multi-dimensional Fokker-Planck type equation (a parabolic diffusion equation) must be integrated numerically. One such approach is to convert the relevant tr…
Propagation of cosmic rays in heliosphere: The HELMOD model
Gervasi, M.; Rancoita, P. G.; Boschini, M. J. +2 more
The heliospheric modulation model HELMOD is a two dimensional treatment dealing with the helio-colatitude and radial distance from Sun and is employed to solve the transport-equation for the GCR propagation through the heliosphere down to Earth. This work presents the current version 3 of the HELMOD model and reviews how main processes involved in…