Scintillating Screens Study for Leir/lhc Heavy Ion Beams

It has been observed on different machines that scintillating ceramic screens (like chromium doped alumina) are quickly damaged by low energy ion beams. These particles are completely stopped on the surface of the screens, inducing both a high local temperature increase and the electrical charging of the material. A study has been initiated to understand the limiting factors and the damage mechanisms. Several materials, ZrO2, BN and Al2O3, have been tested at CERN on LINAC3 with 4.2MeV/u lead ions. Alumina (Al2O3) is used as the reference material as it is extensively used in beam imaging systems. Boron nitride (BN) has better thermal properties than Alumina and Zirconium oxide (ZrO2). BN has in fact the advantage of increasing its electrical conductivity when heated. This contribution presents the results of the beam tests, including the post-mortem analysis of the screens and the outlook for further measurements. The strategy for the choice of the screens for the Low Energy Ion Ring (LEIR), currently under construction at CERN, is also explained.