The technical challenges of the Large Hadron Collider
The Large Hadron Collider (LHC) is a 27 km circumference hadron collider, built at CERN to explore the energy frontier of particle physics. Approved in 1994, it was commissioned and began operation for data taking in 2009. The design and construction of the LHC presented many design, engineering and logistical challenges which involved pushing a number of technologies well beyond their level at the time. Since the start-up of the machine, there has been a very successful 3-year run with an impressive amount of data delivered to the LHC experiments. With an increasingly large stored energy in the beam, the operation of the machine itself presented many challenges and some of these will be discussed. Finally, the planning for the next 20 years has been outlined with progressive upgrades of the machine, first to nominal energy, then to progressively higher collision rates. At each stage the technical challenges are illustrated with a few examples.
Dynamic aperture computation for the as-built CERN Large Hadron Collider
During the design phase of the CERN Large Hadron Collider the dynamic aperture, i.e., the domain in phase space where stable motion occurs, was used as figure-ofmerit to specify the field quality of the various classes of superconducting magnets. The programme of magnetic measurements performed within the framework of the magnets’ acceptance process has produced a large amount of information available, which can be used to estimate the value of the dynamic aperture for the actual machine. In this paper the results of massive numerical simulations based on the measured field quality, both for injection and top energy configurations, are presented and discussed in detail.
Effect of tune modulation on the dynamic aperture of the SSC lattice
The effects of magnet power supply ripple on the long-term dynamic aperture of the SSC lattice by modulating the tunes is modeled. The lattice is represented by a Taylor map of twelfth order in the phase-space coordinates. The transverse tunes parameterizing the rotation matrix (obtained from the linear terms of the map) are sinusoidally modulated at different choices of amplitude and frequency. Particles are tracked through this modulated map for a million turns. The tune modulation results in a decrease of the dynamic aperture. The extent of this decrease depends largely on the tune of the lattice, and to a secondary extent on the amplitude and frequency of the ripple.<<ETX>>