  The upgrade of the normal conducting (NC) Radioactive Ion Beam EXperiment
(REX)-ISOLDE heavy ion accelerator at CERN, under the High Intensity and Energy
(HIE)-ISOLDE framework, proposes the use of superconducting (SC) quarter-wave
resonators (QWRs) to increase the energy capability of the facility from 3
MeV/u to beyond 10 MeV/u. A beam dynamics study of a lattice design comprising
SC QWRs and SC solenoids has confirmed the design's ability to accelerate ions,
with a mass-to-charge ratio in the range 2.5 < A/q < 4.5, to the target energy
with a minimal emittance increase. We report on the development of this study
to include the implementation of realistic fields within the QWRs and
solenoids. A preliminary error study is presented in order to constrain
tolerances on the manufacturing and alignment of the linac.
