Warm and Cold Magnetic and Mechanical Alignment Tests of LHC Short Straight Sections

This paper contains a summary of the results of the magnetic and mechanical alignment tests performed at CERN on the first 111 arc Short Straight Sections. These include the mechanical axis of the Cold Bore Tube at room temperature, the magnetic axis of main quadrupoles and correctors at both room and cryogenic temperature, and the field direction of the main quadrupoles. The measurements show that the quality of the assemblies is generally within the requirements for the machine

I. Introduction

The Large Hadron Collider (LHC) being built at CERN will contain 360 so-called Short Straight Sections (SSS) in the arcs [1], [2]. These assemblies of four twin-aperture Nb-Ti superconducting magnets include either an octupole (MO) or a tuning quadrupole (MQT) corrector, a main quadrupole (MQ), a normal (MS) or skew (MSS) sextupole corrector, and a dipole corrector (MCB). The cold masses work at 1.9 K and are built by Accel, like the MQs, while the assemblies are cryostated and tested at CERN.