# Solution of heliospheric propagation: unveiling the local interstellar spectra of cosmic ray species

## TL;DR

This paper develops a comprehensive framework combining GALPROP and HelMod to accurately determine local interstellar spectra of cosmic rays by fitting a wide range of observational data, improving understanding of cosmic ray propagation.

## Contribution

It introduces an iterative, self-consistent method to derive cosmic ray spectra by integrating galactic and heliospheric propagation models with extensive observational data.

## Key findings

- Successfully reproduces cosmic ray spectra across multiple experiments and energy ranges.
- Provides a unified model consistent with Voyager 1 and near-Earth measurements.
- Enhances understanding of cosmic ray modulation in the heliosphere.

## Abstract

Local interstellar spectra (LIS) for protons, helium and antiprotons are built using the most recent experimental results combined with the state-of-the-art models for propagation in the Galaxy and heliosphere. Two propagation packages, GALPROP and HelMod, are combined to provide a single framework that is run to reproduce direct measurements of cosmic ray (CR) species at different modulation levels and at both polarities of the solar magnetic field. To do so in a self-consistent way, an iterative procedure was developed, where the GALPROP LIS output is fed into HelMod that provides modulated spectra for specific time periods of selected experiments to compare with the data; the HelMod parameters optimization is performed at this stage and looped back to adjust the LIS using the new GALPROP run. The parameters were tuned with the maximum likelihood procedure using an extensive data set of proton spectra from 1997-2015. The proposed LIS accommodate both the low energy interstellar CR spectra measured by Voyager 1 and the high energy observations by BESS, Pamela, AMS-01, and AMS-02 made from the balloons and near-Earth payloads; it also accounts for Ulysses counting rate features measured out of the ecliptic plane. The found solution is in a good agreement with proton, helium, and antiproton data by AMS-02, BESS, and PAMELA in the whole energy range.