Scintillation Screen Studies for High-Dose Ion Beam Applications

Scintillating screens are commonly used at accelerator facilities. However, their imaging qualities are not well understood, especially for high-current ion beam operation. Several types of inorganic scintillators were investigated for various ion species and energies of 4.8 and 11.4 MeV/u. For ion beam applications, the exact reproduction of the beam profile is of great importance. Due to the impact by ions, the dose rate during beam delivery is more than 10 orders of magnitude higher as for other applications of scintillators in typical nuclear physics experiments. To validate the imaging quality of the scintillators, different profile measurement methods are compared. Ceramic Al₂O₃ showed the best results compared to other ceramics like ZrO₂ :Y or quartz glass Herasil 102. The imaging properties of the materials can depend significantly on the ion energy. For Al₂O₃ irradiated with a Ca beam the of 4.8 MeV/u, the results agree with the reference methods. However, for 11.4 MeV/u, the screen image does not reflect the beam distribution, which cannot be attributed to material degradation. A model is under development taking into account the radial dose distribution along the ion track as well as the overlap of tracks. For Al₂O₃ , this model can describe the observed saturation effect and is able to reconstruct saturated images. The basics and applications of this model are discussed. Detailed spectroscopic investigations were performed to determine the influence of the ion beam intensity on the luminescence spectra emitted by the materials. No significant dependence on the spectra with respect to the beam intensity was found for most of the scintillators.