Simulation of an Intra-Pulse Interaction Point Feedback for Future Linear Colliders

In future normal-conducting linear colliders, the beams will be delivered in short bursts with a length of the order of 100 ns. The pulses will be separated by several ms. In order to maintain high luminosity, feedback is necessary on a pulse-to-pulse basis. In addition, intra-pulse feedback that can correct beam positions and angles within one pulse seem technically feasible. The likely performances of different feedback options are simulated for the NLC (Next Linear Collider) and CLIC (Compact Linear Collider).Comment: LINAC2000 Conference, Paper ID MOA0

Beam Loading Compensation in the Main Linac of CLIC

Compensation of multi-bunch beam loading is of great importance in the main linac of the Compact Linear Collider (CLIC). The bunch-to-bunch energy variation has to stay below 1 part in 1000. In CLIC, the RF power is obtained by decelerating a drive beam which is formed by merging a number of short bunch trains. A promising scheme for tackling beam loading in the main linac is based on varying the lengths of the bunch trains in the drive beam. The scheme and its expected performance are presented.Comment: LINAC 2000, paper ID MOA0

Beam-based alignment in the new CLIC Main LINAC

In the main linac of the compact linear collider (CLIC) the beam induced wakefield and dispersive effects will be strong. In the paper the reference beam-based alignment procedure for the new CLIC parameters is specified and the resulting tolerances for static imperfections are detailed

Multi-Bunch calculations in the CLIC Main LINAC

In the main linac of the compact linear collider (CLIC [1]) , wakefield induced multi-bunch effects are important. They have a strong impact on the choice of accelerating structure design. The paper presents the limit for the wakefield that one bunch exerts on the next. It also gives estimates for the allowed level of persistent wake fields and on the resistive wall wakefield

Regular Incidence Complexes, Polytopes, and C-Groups

Regular incidence complexes are combinatorial incidence structures generalizing regular convex polytopes, regular complex polytopes, various types of incidence geometries, and many other highly symmetric objects. The special case of abstract regular polytopes has been well-studied. The paper describes the combinatorial structure of a regular incidence complex in terms of a system of distinguished generating subgroups of its automorphism group or a flag-transitive subgroup. Then the groups admitting a flag-transitive action on an incidence complex are characterized as generalized string C-groups. Further, extensions of regular incidence complexes are studied, and certain incidence complexes particularly close to abstract polytopes, called abstract polytope complexes, are investigated.Comment: 24 pages; to appear in "Discrete Geometry and Symmetry", M. Conder, A. Deza, and A. Ivic Weiss (eds), Springe

Conversion efficiency and luminosity for gamma-proton colliders based on the LHC-CLIC or LHC-ILC QCD Explorer scheme

Gamma-proton collisions allow unprecedented investigations of the low x and high $Q^{2}$ regions in quantum chromodynamics. In this paper, we investigate the luminosity for "ILC"$\times$LHC ($\sqrt{s_{ep}}=1.3$ TeV) and "CLIC"$\times$LHC ($\sqrt{s_{ep}}=1.45$ TeV) based $\gamma p$ colliders. Also we determine the laser properties required for high conversion efficiency.Comment: 16, 6 figure

Quantum Algorithmic Readout in Multi-Ion Clocks

Optical clocks based on ensembles of trapped ions offer the perspective of record frequency uncertainty with good short-term stability. Most suitable atomic species lack closed transitions for fast detection such that the clock signal has to be read out indirectly through transferring the quantum state of clock ions to co-trapped logic ions by means of quantum logic operations. For ensembles of clock ions existing methods for quantum logic readout require a linear overhead in either time or the number of logic ions. Here we report a quantum algorithmic readout whose overhead scales logarithmically with the number of clock ions in both of these respects. We show that the readout algorithm can be implemented with a single application of a multi-species quantum gate, which we describe in detail for a crystal of Aluminum and Calcium ions.Comment: 4 pages + 7 pages appendix; 5 figures; v3: published versio

Alignment Tolerances for the CLIC Decelerator

This note aims to quantify the alignment tolerances for the CLIC decelerator lattice elements by investigating the effects of wake fields and component misalignment. The tolerances comes from the requirements of transporting the entire beam through the lattice, while extracting the required amount of energy. First, we briefly discuss the beam energy spread and its effect on the beam envelope. Then, we analyze the effects of the PETS dipole wakes for a perfect machine. Finally, the effect of lattice element misalignment is studied. Beam based alignment schemes for quadrupole correction will be presented, including modifications of the schemes needed for the CLIC decelerating station. Simulations have been performed with the tracking code PLACET . The results indicate, for an energy extraction efficiency of 85%, that it would be possible to transport the entire decelerator beam through the lattice, if PETS misalignment are not larger than ~100 um and if beam based alignment methods are used for quadrupole correction