Isotope solar modulation with the PAMELA experiment 2019
View/ Open
Date
2019Author
Munini, Riccardo
Aslam, O.P.M.
Bisschoff, D.
Potgieter, M.S.
Metadata
Show full item recordAbstract
The satellite-borne PAMELA experiment was launched on the 15th June 2006 from the Baikonur
cosmodrome. Since then and until January 2016 PAMELA made high-precision measurements
of the charged component of cosmic-rays over a wide energy range. Because of its long-duration
operation, PAMELA represents an ideal detector for cosmic-ray solar modulation studies. The
PAMELA collaboration already published time-dependent proton, helium and electron spectra as
well as the positron to electron ratio over ten years of data taking. These results are fundamental
to improve and refine propagation models the propagation models of cosmic rays through the
heliosphere.
Here, the yearly average spectra over the 23rd solar minimum (July 2006 - January 2009) until
the middle of the 24rd solar maximum (December 2015) for 1H, 2H, 3He and 4He are presented.
The isotopic composition was measured between 0.1 and 1.1 GeV/n using two different detector
systems. These spectra show an increasing trend during the solar minimum period with a decrease
as the solar maximum is approached. The time-dependent ratio of these isotopes is also presented.
From a solar modulation point of view, a non constant ratio is typically caused by their different
masses (related to their rigidity) and also the different shapes of the respective local interstellar
spectra. Apart from these effects, it is worthwhile to look deeper for more fundamental causes
related to their propagation and modulation mechanisms