Resonance free lattices for A.G. machines

A part of an alternating gradient circular machine composed of a number of identical cells Nc will not contribute to the excitation of most of the non-linear resonances to first order in multipole strength, if the two phase advances per cell take the values 2*k1/Nc and 2*k2/Nc. k1 and k2 are any integers and k1 AB AF AN AU AUForm AccNum BN CDate CTown ConfName DB Dat Format MainFile Num PR2 RN Records SU SuD SuE SuN TI errors files k2. This property is demonstrated here. Its application to synchrotron light sources and colliders is discussed

Geometry of the Muon Storage Ring 325

Possible geometries of a muon storage ring have been determined from the requirement of the position of the detectors. If the detector distances are specified and not their azimuth, there remains one freeparameter to determine the geometry. It can be used for instance tooptimize the slope of the machine plane. On the CERN site the maximumheight of the storage ring is limited by the thickness of the molasseto less than 300m. Then the maximum length of the straight section pointing to the far detector is about 800m. For a ring of triangularshape with two equal sides, this length represents about 36% of the ring circumference using 4T dipoles in the arcs. The overall maximum tunnel slope is 33o

Revision of the Closed Orbit Corrector System of the LHC

The closed orbit corrector system of the LHC has been revisited in accordance with the project progress. The magnet measurement procedures are now well defined. This makes the error on the magnet strength and positioning better known than at the time the orbit correctors were specified. The LHC is in a favourable context in the sense that we have a precise knowledge of the vertical movement of the LEP tunnel and that an efficient code to detect field errors is available. Under these conditions the strength of the closed orbit correctors in the arc and in the dispersion suppressors is sufficient. The demand on closed orbit correctors in the insertions can be somewhat relaxed. The tolerances on the longitudinal positions of the dipoles and quadrupoles are easy to satisfy and do not impose further constraints on the closed orbit corrector system

Non-linear chromaticity correction with sextupole families

The correction of the non-linear chromaticity with sextupoles families is explained by means of a simple perturbation theory. The advantages and limitations of such systems are shown, as well as the constraints they put on machine optics

RLA design: RF optics

Opposite to the synchrotrons which work at fixed optics, the Recirculating Linear Accelerators work with a variable optics in the RF system. This is due to the increase of the particle energy at subsequent passages, which results in a decrease of the normalised quadrupole strengths. It is demonstrated in this note that this effect does not introduce any limitation in the total energy gain if FODO cells are used in the RF system. Consequently, a single recirculator could be designed to accelerate from 2GeV to 50GeV if there is no need of a first recirculator for any other reasons like bunch shaping or matching

Computation of fixed points in a circular machine

This paper describes an algorithm to compute the fixed points (closed orbit or higher order fixed points) in a circular machine together with the linear transformation around it by tracking trajectories on a small number of turns. It can be applied to a phase space with an arbitrary number of dimensions. It is particularly useful to check the consistency between trajectory tracking and transfer matrix calculation in any optics code

Optics Studies for Diffractive Physics at the LHC

Forward protons with momenta close to the beam-momentum arise either from elastic scattering or from single or double diffraction. These protons are very close to the beamline and can only be measured downstream using "beam close detectors". In this paper we present a complete study of the optics (low, medium and high beta), possible locations of the detectors and running scenarios for these measurements at insertions IR1 and IR5 of the LHC. These optics are compatible with the latest layout of the LHC insertions and the commissioning beam parameters

Possible resonance free lattices for the VLHC

A systematic search for resonance-free lattices has been performed. Numerous solutions exist for sets of about fifty cells. A VLHC-like machine could be made of blocks of 61 cells which are free from resonances up to tenth order. A tracking test shows a 20% improvement of the dynamic aperture with respect to standard cells, for several multi-pole components. It opens the possibility of relaxing the constraints on systematic multipole components for the cells. The tolerances on field quality will then be by chromatic and an-harmonic effects of the mul-tipole components