Gaia will only achieve its unprecedented measurement accuracy requirements with detailed
calibration and correction for radiation damage. We present our Silvaco 3D engineering
software model of the Gaia CCD pixel and two of its applications for Gaia: (1) physically
interpreting supplementary buried channel (SBC) capacity measurements (pocket-pumping and
first pixel response) in terms of e2v manufacturing doping alignment tolerances; and (2)
deriving electron densities within a charge packet as a function of the number of
constituent electrons and 3D position within the charge packet as input to microscopic
models being developed to simulate radiation damage.