Radiation protection study related to the future post-accelerator of the HIE-ISOLDE project

The HIE-ISOLDE project aims at expanding the physics programme of the ISOLDE facility at CERN. In particular, the addition of a superconducting linac will allow the post-acceleration of radioactive ion beams up to 10 MeV/u. However, because of field emission in the superconducting cavities and the possibility of neutron production for ion interactions above the Coulomb barrier, new radiological hazards need to be mitigated. Measurements of dose rate levels close to cavity prototypes were used to determine the intensity of the source of X ray due to field emission for a single cavity. The results were extrapolated to the operation of the 32 cavities that will be installed, and a detailed FLUKA calculation was performed to determine the required shielding to minimise the exposure of personnel present in the ISOLDE experimental hall during operation. FLUKA was also used to determine the maximum ambient dose equivalent rate levels in the accessible part of the hall due to ion beam losses for the envelope energies and intensities.