CERN, Geneva
PSI, Villigen
BNL, Upton, Long Island, New York
Optics stability during all phases of operation is crucial for the LHC. The optical properties of the machine have been optimized based on a detailed magnetic model of the SC magnets and on their sorting. Tools and procedures have been developed for rapid checks of beta beating, dispersion, and linear coupling, as well as for prompt optics correction. Initial optics errors, correction performance and optics stability from the first LHC run will be reported, and compared with expectations. Possible implications for the collimation cleaning efficiency and LHC machine protection will be discussed.
GSI, Darmstadt
CERN, Geneva
The measurement of synchrotron nonlinear components is an essential step for devising an effective compensation scheme for improving machine performances. A validation test of a recently proposed method called nonlinear tune response matrix (NTRM) for measuring circular accelerator nonlinear components is undergoing in a CERN-GSI joint effort. The test consists in the attempt of reconstructing few controlled octupolar components in the SPS synchrotron. In this proceeding we report on the SPS benchmarking experiment and discuss the performances the NTRM method applied to this measurements.
CERN, Geneva
BNL, Upton, Long Island, New York
Consolidation of the coupling correction scheme in the LHC is motivated due to a missing skew quadrupole family in Sector 3-4 at the start-up in 2009. Simultaneous coupling and vertical dispersion correction using vertical orbit bumps at the sextupoles, was studied by analyzing turn-by-turn data. This scheme was tested in SPS where the optical structure of arc cells is quite similar to the LHC. In SPS, horizontal and vertical beam positions are measured separately with single plane BPMs, thus a technique to construct "pseudo double plane BPM" is also discussed.
CERN, Geneva
BNL, Upton, Long Island, New York
After the incident in the LHC in 2008, few skew quadrupoles were damaged and subsequently removed from the tunnel. This could limit the correction of local coupling in the LHC. In order to increase the flexibility in the coupling correction it has been proposed to use of vertical orbit bumps at the sextupoles is studied. Moreover a simultaneous coupling and vertical dispersion can be implemented. Various studies are presented addressing the optimal approach for the correction of the vertical dispersion and the sum and difference coupling resonances.
CERN, Geneva
BNL, Upton, Long Island, New York
A software package has been developed for the LHC on-line optics measurement and correction. This package includes several different algorithms to measure phase advance, beta functions, dispersion, coupling parameters and even some non-linear terms. A Graphical User Interface provides visualization tools to compare measurements to model predictions, fit analytical formula, localize error sources and compute and send corrections to the hardware.
CERN, Geneva
During the first years of operation of the LHC unknown field errors or misalignments could lead to unmatched optics and discrepancies with respect to the model. This could affect some critical parameters such as the luminosity or the lifetime. It is therefore desirable to implement tools which allow for fine tuning of the IP optics and could be used during the commissioning phase of the LHC. In this paper we report on the implementation the performances and the limitations of these commissioning tools.
BNL, Upton, Long Island, New York
PSI-LRF, Villigen, PSI
CERN, Geneva
Measurements of chromatic beta-beating were carried out for the first time in the RHIC accelerator during Run 2009. The analysis package developed for the LHC was used to extract the off-momentum optics for injection and top energy. Results from the beam experiments and comparison to the optics model are presented.