Comparison of electrons PAD at different energy levels from the REPT and MagEIS instrument on board Van Allen Probe B on 2014 September 12 from 17:00 to 21:00 UT. (a) Normalized PAD electron flux at the 466.8 keV energy level. (b) Sequences of PAD during the interval selected in the black box above (19:40–20:31 UT) representing the beginning of EMIC waves. (c) Normalized PAD electron flux at the 1.80 MeV energy level. Butterfly PAD at (d) 1.80 MeV energy channel. The solid line represents the instant before EMIC waves, and the dotted line during EMIC waves shown in (c) as black arrows.