• K. Fuchsberger, V. Baggiolini, R. Gorbonosov, W. Herr, V. Kain, G.J. Müller, S. Redaelli, F. Schmidt, J. Wenninger
  CERN, Geneva

MADX (Methodical Accelerator Design) is the de-facto standard software for modeling accelerator lattices at CERN. This feature-rich software package is implemented and maintained in the programming languages C and FORTRAN. Nevertheless the controls environment of modern accelerators at CERN, e.g. of the LHC, is dominated by JAVA applications. A lot of these applications, for example for lattice measurement and fitting, require a close interaction with the numerical models, which are all defined by the use of the proprietary MADX scripting language. To close this gap an API to MADX for the JAVA programming language (JMAD) was developed. Already the current implementation provides access to a large subset of the MADX capabilities (e.g. twiss-calculations, matching or querying and setting arbitrary model parameters) without any necessity to define the models in yet another environment. This paper describes shortly the design of this project as well as the current status and some usage examples.

• M. Meddahi, S.D. Fartoukh, K. Fuchsberger, B. Goddard, W. Herr, V. Kain, V. Mertens, J. Wenninger
  CERN, Geneva
• D. Kaltchev
  TRIUMF, Vancouver

In 2008, the SPS-to-LHC transfer line operation allowed for the first time to perform beam measurements in the last part of the lines and into the LHC. Beam parameters were measured and compared with expectation. Discrepancies were observed in the dispersion matching into the LHC, and also in the vertical phase advance along the line. In 2009, extensive theoretical and simulation work was performed in order to understand the possible sources of these discrepancies. This allowed establishing an updated model of the beam line, taking into account the importance of the full magnetic model, the limited dipole corrector strengths and the precise alignment of beam elements. During 2009, beam time was allocated in order to perform further measurements, checking and refining the optical model of the transfer line and LHC injection region and validating the different assumptions. Results of the 2009 optics measurements and comparison with the beam specification and model are presented.

• J. Snuverink, W. Herr, C. Jach, J.B. Jeanneret, D. Schulte, F. Stulle
  CERN, Geneva

The Compact Linear Collider (CLIC) accelerator has strong precision requirements on the position of the beam. The beam position will be sensitive to external dynamic magnetic fields (stray fields) in the nanotesla regime. The impact of these fields on the CLIC main beam has been studied by performing simulations on the lattices and tolerances have been determined. Several mitigation techniques will be discussed.