Rigidity dependence and time response of cosmic rays to the modulation steps in the rising part of Solar cycle 23. COSPIN/KET results

Previous work on the latitudinal gradient and on the amplitude of the recur rent cosmic ray decreases, has shown that their magnitude does not decrease monotonically with the particle rigidity, but it presents a broad maximun around 1-2 GV. We have extended this analysis to study the behaviour of cos mic-ray particles during the modulation steps in the rising part of the sol ar activity of the present Solar cycle. We found that the `depth' of the mo dulation step decreases monotonically with increasing rigidity and that the least energetic particles are the last to reach their minimum intensity va lue. We also considered in this analysis electrons of equal rigidity to stu dy the influence of the charge sign on the particle behaviour during the mo dulation steps.