Neutron monitors and muon detectors for solar modulation studies: 2. φ time series

The level of solar modulation at different times (related to the solar activity) is a central question of solar and galactic cosmic -ray physics. In the first paper of this series, we have established a correspondence between the uncertainties on ground-based detectors count rates and the parameter phi (modulation level in the force-field approximation) reconstructed from these count rates. In this second paper, we detail a procedure to obtain a reference phi time series from neutron monitor data. We show that we can have an unbiased and accurate phi reconstruction (Delta phi/phi similar or equal to 10%). We also discuss the potential of Bonner spheres spectrometers and muon detectors to provide phi time series. Two by-products of this calculation are updated phi values for the cosmic-ray database and a web interface to retrieve and plot phi from the 50's to today(http://lpsc.in2p3.fr/crdb). (C) 2016 COSPAR. Published by Elsevier Ltd. All rights reserved.