An Achromatic Optics for the Linac 2 to Booster Transfer Line

This paper is a summary of simulations and experiments carried out in order to understand the optics of the transfer line from the CERN proton linac (Linac~2) to the CERN PS Booster (PSB). As a result of the studies, a cable inversion between two quadrupoles could be identified and the optics of this transfer line is now fully understood. The model of the line has been used to match an achromatic optics, which was successfully put in place in 2005. The new optics has improved significantly the injection efficiency into the PSB and is beneficial for high brilliance LHC type beams.