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The local interstellar spectra (LISs) for galactic cosmic rays (CRs) cannot be directly observed at the Earth below certain energies, because of solar modulation in the heliosphere. With Voyager 1 crossing the heliopause in 2012, in situ experimental LIS data below 100 MeV/nuc can now constrain computed galactic CR spectra. Using galactic propagation models, galactic electron, proton, and light nuclei spectra can now be computed more reliably as LISs. Using the Voyager 1 observations made beyond the heliopause, and the observations made by the PAMELA experiment in Earth orbit for the 2009 solar minimum, as experimental constraints, we simultaneously reproduced the CR electron, proton, helium, and carbon observations by implementing the GALPROP code. Below about 30 GeV/nuc solar modulation has a significant effect and a comprehensive three-dimensional (3D) numerical modulation model is used to compare the computed spectra with the observed PAMELA spectra at these energies. Subsequently the computed LISs can be compared over as wide a range of energies as possible. The simultaneous calculation of CR spectra with a single propagation model allows the LISs for positrons, boron, and oxygen to also be inferred. This implementation of the comprehensive galactic propagation model (GALPROP), alongside a sophisticated solar modulation model to compute CR spectra for comparison with both Voyager 1 and PAMELA observations over a wide energy range, allows us to present new self-consistent LISs (and expressions) for electrons, positrons, protons, helium, carbon, boron, and oxygen for the energy range of 3 MeV/nuc–100 GeV/nuc. [ABSTRACT FROM AUTHOR]

Heliospheric modulation conditions were unusually quiet during the last solar minimum activity between solar cycles 23 and 24. Fortunately, the PAMELA space experiment measured 6 month–averaged Galactic positron spectra for the period 2006 July to 2009 December over an energy range of 80 MeV to 30 GeV, which is important for solar modulation. The highest level of Galactic positrons was observed at Earth during the 2009 July–December period. A well-established, comprehensive three-dimensional (3D) numerical model is applied to study the modulation of the observed positron spectra. This model had been used previously to understand the modulation of Galactic protons and electrons also measured by PAMELA for the same period. First, a new, very local interstellar spectrum for positrons is constructed using the well-known GALPROP code, together with the mentioned PAMELA observations. The 3D model is used to distinguish between the dominant mechanisms responsible for the heliospheric modulation of Galactic positrons and understand the effect of particle drift during this unusual minimum in particular, which is considered diffusion-dominant, even though particle drift still had a significant role in modulating positrons. Lastly, the expected intensity of Galactic positrons during an A > 0 polarity minimum, with similar heliospheric conditions than for 2006–2009, is predicted to be higher than what was observed by PAMELA for the 2006–2009 unusual minimum. [ABSTRACT FROM AUTHOR]