A LOW GRADIENT TRIPLET QUADRUPOLE LAYOUT COMPATIBLE WITH NbTi MAGNET TECHNOLOGY AND β * = 0.25m *
The paper presents a triplet layout option with long (about 100m total triplet length), low gradient (45T/m to 70T/m) quadrupole magnets. Assuming a maximum magnet diameter of 200mm, the peak coil field at the magnet coils still remains below 7T which is still compatible with conventional NbTi magnet technology. The peak beta function inside the triplet magnets reaches 22km and the configuration therefore requires an additional chromaticity correction scheme similar to a dipole first layout option. However, at the same time, the presented solution provides an interesting alternative to a high gradient triplet layout which requires the new Nb3Sn magnet technology.
Limits of chromaticity correction
The LHC luminosity upgrade supposes from the point of view of the optics the upgrade of the Interaction Regions (IR) of the main experiments ATLAS and CMS. This upgrade is expected to provide a of 25 cm instead of the 50 cm of the nominal one. This decreasing in implies an increasing of the maximum in the lowquadrupoles and subsequently a more difficult chromaticity correction. In this report we analyze ithe limits and possible strategies on the chromaticity correction for the different optics proposed for the upgrade of the IR.
Weak-strong beam-beam simulations for the Large Hadron Collider
A weak-strong simulation code is used to study the single-particle stability in the presence of triplet field errors, head-on collisions, and long-range beam-beam interactions at the Large Hadron Collider. We present the dependence of the simulated transverse diffusion rate on various parameters, such as starting amplitude, working point in tune diagram, crossing angle, beta function at the interaction points (IPs), beam current, triplet nonlinearities, tune modulation, and a transverse offset at one of two IPs. For several examples, we perform a frequency map analysis à la Laskar, to obtain tune footprints and the tune variation in time. A cursory look at the effect of a Möbius lattice is also reported.