Optics Studies of the LHC Beam Transfer Line TI 8

J Wenninger,Y.-C Chao,M Lamont,J Uythoven,D Jacquet,G Arduini,B Goddard,V Mertens,V Kain

doi:10.1109/pac.2005.1590841

Abstract

The optics of the newly commissioned LHC beam transfer line TI 8 was studied with beam trajectories, dispersion and profile measurements. Steering magnet response measurements were used to analyze the quality of the steering magnets and of the beam position monitors. A simultaneous fit of the quadrupole strengths was used to search for setting or calibration errors. Residual coupling between the planes was evaluated using high statistics samples of trajectories. Initial conditions for the optics at the entrance of the transfer line were reconstructed from beam profile measurements with Optical Transition Radiation monitors. The paper presents the various analysis methods and their errors. The expected emittance growth arising from optical mismatch into the LHC is evaluated.

Highlights

Ti 8, the first 2.7 km long transfer line between the Super Proton Synchrotron (SPS) and the LHC was commissioned in the autumn of 2004 [1]
Initial conditions for the optics at the entrance of the transfer line were reconstructed from beam profile measurements with Optical Transition Radiation monitors
This paper presents the studies of the TI 8 transfer line optics based on measurements of the trajectory response, the dispersion function and beam profile measurements

Summary

INTRODUCTION

Ti 8, the first 2.7 km long transfer line between the Super Proton Synchrotron (SPS) and the LHC was commissioned in the autumn of 2004 [1]. The data sample was fitted with LOCO using as free parameters all BPM and corrector calibration factors and well as the strength of the main QF and QD quadrupole magnet families. To localize the source of the optics error, the LOCO fits were repeated using successively the strength of each quadrupole in the first part of the line as free parameter. The dispersion in the transfer line was obtained by measuring trajectories in TI 8 for different RF frequency settings in the SPS at extraction. During the first measurement period large deviations of the horizontal dispersion from the design model were observed Those deviations were due to the focusing strength error described, and the problem was cured for the second period.

Design

Findings

CONCLUSION