  We take advantage of the cosmic-ray (CR) proton data collected by the PAMELA
detector in several campaigns covering the period 2006-2009 to derive the local
interstellar CR proton spectrum (LIS), outside the solar system. We describe
the propagation of CR protons in the solar system by means of a detailed model
of the charge-sign dependent drifts occurring while CRs diffuse in the
irregular solar magnetic field. We fit PAMELA data for each year of data taking
and find that they are well described by a unique time-independent LIS. We then
discuss the consequences of this LIS on galactic propagation models. We find
that diffusive reacceleration is strongly constrained, thus confirming previous
results derived from different channels.
