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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 ecliptic plane, as well as at different distances from Sun in the inner and outer heliosphere. The GCRs mainly constitute the high-energy population of the so-called space radiation environment. Modulated cosmic-ray spectra of protons and nuclei, obtained from HelMod and other solar modulation codes were compared to the AMS–02 spectra ranging from GeV up to TeV energies. Concerning other commonly used solar modulation models, HelMod modulated spectra are available over the entire rigidity range and observation period of AMS–02 mission. A quantitative comparison among models was carried out using Δ Φ , i.e., the relative difference between the experimental and simulated fluences, and η RMS , i.e., the error-weighted root mean square of the relative difference between AMS–02 experimental data and simulated differential intensities. HelMod was found to achieve a good agreement over the full set of experimental data with, typically, Δ Φ within ± 2.5 % and η RMS within 5%. Usually larger or, in a few cases, much larger values for Δ Φ and η RMS were found for the other models. [ABSTRACT FROM AUTHOR]

HelMod model allows one to describe how solar modulation affects the propagation of galactic cosmic rays (GCR) through the heliosphere with an accuracy of the level of actual experimental uncertainties. The GCRs mainly constitute the high energy population of the so-called space radiation environment. The model treats the physical processes involved in solar modulation, like diffusion, particle drift, convection and adiabatic energy losses, and it embeds a description of both the inner and outer heliosphere. To obtain the modulated intensities, the model requires the knowledge of a few time-dependent heliospheric quantities, i.e., sunspot number, tilt angle of the neutral current sheet, solar wind speed and density, and interplanetary magnetic field. Using historical records, we present a template-based procedure that allows one to predict the heliospheric parameters for coming years, and, in turn, the forecasted modulated spectra. The forecasting templates reconstruct the typical time variation along with solar cycles and may be tuned to the current solar cycle. We estimate that the uncertainty of the forecasted cosmic rays intensity is below 5% (± 10 % at 68% C.L.) on average for short time predictions (up to 4 years), and below 15% (± (20 - 25) % at 68% C.L.) for long time predictions (up to 11 years). [ABSTRACT FROM AUTHOR]

H el M od is a Monte Carlo code developed to describe the transport of Galactic Cosmic Rays (GCRs) through the heliosphere from the interstellar space to the Earth. In the current H el M od version 4 the modulation process, based on Parker's equation, is applied to the propagation of GCRs in the inner and outer heliosphere, i.e., including the heliosheath. H el M od was proved to reproduce protons, nuclei and electrons cosmic rays spectra observed during solar cycles 23–24 by several detectors, for instance, PAMELA, BESS and AMS-02. In particular, the unprecedented accuracy of AMS-02 observations allowed one a better tuning of the description regarding the solar modulation mechanisms implemented in H el M od. In addition, H el M od demonstrated to be capable of reproducing the fluxes observed by the Voyager probes in the inner and outer regions of heliosphere up to its border. [ABSTRACT FROM AUTHOR]

Abstract The heliospheric modulation model H el M od 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 H el M od model and reviews how main processes involved in GCR propagation were implemented. The treatment includes the so-called particle drift effects – e.g., those resulting, for instance, from the extension of the neutral current sheet inside the heliosphere and from the curvature and gradient of the IMF –, which affect the transport of particles entering the solar cavity as a function of their charge sign. The H el M od model is capable to provide modulated spectra which well agree within the experimental errors with those measured by AMS-01, BESS, PAMELA and AMS-02 during the solar cycles 23 and 24. Furthermore, the counting rate measured by Ulysses at ± 80 ° of solar latitude and 1–5 AU was also found in agreement with that expected by H el M od code version 3. [ABSTRACT FROM AUTHOR]

Abstract: In the present work, an improved numerical solution for determining the ratio, , of the unscreened Mott differential cross section (MDCS) with respect to Rutherford's formula is proposed for the scattering of electrons and positrons on nuclei with . It accounts for incoming lepton energies between 1keV and 900MeV. For both electrons and positrons, a fitting formula and a set of fitting coefficients for the ratio on nuclei are also presented. The found average error of the latter practical interpolated expression is typically lower than 1% also at low energy for electrons and lower than 0.05% for positrons for all nuclei over the entire energy range. Both the improved numerical solution and the interpolated practical expression were found in good agreement with the partially available previous calculations. [Copyright &y& Elsevier]

Abstract: At 1AU and outside the Earth’s magnetosphere, the relative abundances to protons for He (He/p), C (C/p) and Fe (Fe/p) nuclei were calculated using the observation data of AMS-01 (for p and He) and HEAO-3 (for C and Fe) above 0.8GeV/nucleon. In addition, the transmission function (TF) for the GCR propagation inside the magnetosphere was evaluated using the IGRF and T96 (introduced by Tsyganenko and Stern) models to obtain permitted and forbidden trajectories inside the magnetosphere. The TF allowed one to derive the primary He-nuclei fluxes in the same geomagnetic regions of AMS-01 observations. These fluxes were found in good agreement with the observation data. Furthermore inside the magnetosphere in addition to the flux of helium, it allowed one to obtain those of the primary p, C, and Fe nuclei and the relative abundances of He, C and Fe nuclei to protons from the same observation data of AMS-01 and HEAO-3 above ≈0.8GeV/nucleon. Up to a geomagnetic latitude of ≈45.84°, the relative isotopic abundances were found to depend on the mass number I isot and, on average, range from a factor ≈2.31 up to ≈3.35 larger than those outside the magnetosphere at 1AU. Thus, the magnetospheric isotopic/nuclear relative abundances differ from those inside the solar cavity and those in the interstellar space. The usage of the TF approach can allow one to determine the nuclear abundances in the magnetosphere at any geomagnetic latitude and, thus, any orbit, provided that the CR spectra are determined at 1AU. [Copyright &y& Elsevier]

The Alpha Magnetic Spectrometer (AMS) is a precision particle physics detector on the International Space Station (ISS) conducting a unique, long-duration mission of fundamental physics research in space. The physics objectives include the precise studies of the origin of dark matter, antimatter, and cosmic rays as well as the exploration of new phenomena. Following a 16-year period of construction and testing, and a precursor flight on the Space Shuttle, AMS was installed on the ISS on May 19, 2011. In this report we present results based on 120 billion charged cosmic ray events up to multi-TeV energies. This includes the fluxes of positrons, electrons, antiprotons, protons, and nuclei. These results provide unexpected information, which cannot be explained by the current theoretical models. The accuracy and characteristics of the data, simultaneously from many different types of cosmic rays, provide unique input to the understanding of origins, acceleration, and propagation of cosmic rays. [ABSTRACT FROM AUTHOR]