  Since the beginning of the space exploration era, solar activity was observed
at its lowest level during 2006 to 2009. During this period, the PAMELA space
experiment observed spectra for galactic cosmic rays, specifically for protons,
electrons and positrons over a wide energy range, during what is called an A <
0 solar magnetic polarity cycle. Drift theory predicts a difference in the
behaviour for these oppositely charge particles during A < 0 cycles. An
opportunity was thus created to study the predicted charge-sign-dependent
modulation, also now for very quiet heliospheric conditions. A comprehensive
three-dimensional, drift modulation model has been used to study the solar
modulation for cosmic rays in detail with extensive comparison to the observed
PAMELA spectra for the mentioned period. First, this was done for protons and
secondly for electrons, as already published, to test and to authenticate the
modelling approach and then to come to a better understanding and appreciation
of the underlying physics, such as diffusion and drift theory. The results were
also used to make predictions of how cosmic rays are differently modulated down
to low energies (1 MeV) for the two magnetic polarity cycles of the Sun, and
what role drifts play in this process. All computed solutions are based on new
very local interstellar spectra, now also done for positrons. This report is
focussed on detailed aspects of the solar modulation of positrons during the
extraordinary quiet solar modulation period from 2006 to 2009. For the first
time, a meaningful modulation factor in the heliosphere is computed for
positrons, from 50 GeV down to 1 MeV, as well as the electron to positron
ratios as a function of time and rigidity for the mentioned period.
