0.5 - 165 MeV proton and 102 - 312 keV electron injections during the 2006 December 13 SEP event

The last large solar energetic particle event of solar cycle 23 was observed on 2006 December 13. The origin of this event was associated with a X3.4 flare from AR10930 at S06W23 and a fast (> 1700 km/s) halo CME. A long-lasting type III and a metric type II radio burst were also recorded. We combine proton observations from ACE/EPAM, SOHO/ERNE and STEREO/IMPACT (24 energy channels from 0.5 to 165 MeV) to model the proton differential intensities measured during this event. We simulate both the propagation of the CME-driven shock (from 4 solar radii to 1 AU) and the transport of shock-accelerated protons along the upstream interplanetary magnetic field lines. Near-relativistic (102 - 312 keV) electron observations by ACE/EPAM during the early phase of the event are used to constrain the electron transport conditions along the field lines and deduce, via a Monte Carlo transport model, the electron injection profile close to the Sun. The best-fit electron injection profile shows one prompt component consistent with the timing and duration of both the radio type III and the hard X-ray bursts and a second delayed injection component timely associated with the type II radio burst. From the proton modelling we quantify the injection rate of shock accelerated protons and show that most of the > 50 MeV protons are injected when the shock is still close to the Sun (i.e. within 42 solar radii). We compare the inferred electron and proton injections and discuss the possible contribution of flare-related particles in the early phase of the event.