CLASSE, Ithaca, New York
CERN, Geneva
Carleton University, College of Natural Sciences, Ottawa, Ontario
Purdue University, West Lafayette, Indiana
LBNL, Berkeley, California
Grove City College, Grove City, Pennsylvania
INFN/LNF, Frascati (Roma)
ASCo, Clayton, Victoria
KEK, Ibaraki
Clarkson University, Potsdam, New York
BNL, Upton, Long Island, New York
ANL, Argonne
CalPoly, San Luis Obispo, CA
Cockcroft Institute, Warrington, Cheshire
SLAC, Menlo Park, California
Fermilab, Batavia
Technion, Haifa
Loyola University, Chicago, Illinois
The Cornell Electron Storage Ring (CESR) has been reconfigured as a test accelerator (CesrTA) for a program of electron cloud (EC) research at ultra low emittance. The instrumentation in the ring has been upgraded with local diagnostics for measurement of cloud density and with improved beam diagnostics for the characterization of both the low emittance performance and the beam dynamics of high intensity bunch trains interacting with the cloud. Finally a range of EC mitigation methods have been deployed and tested. Measurements of cloud density and its impact on the beam under a range of conditions will be presented and compared with simulations. The effectiveness of a range of mitigation techniques will also be discussed.
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
STFC/DL, Daresbury, Warrington, Cheshire
The University of Liverpool, Liverpool
Cockcroft Institute, Warrington, Cheshire
BINP SB RAS, Novosibirsk
A vacuum vessel design of wiggler sections should meet a few challenging specification. The SR power of about 40 kW is generated in each wiggler. Expanding fan of SR radiation reaches the beam vacuum chamber walls in the following wiggler and may cause the following problem: massive power dissipation on vacuum chamber walls inside the cryogenic vessel, radiation damage of superconducting coil, high photo-electron production rate that cause an e-cloud build-up to unacceptable level. Therefore this power should be absorbed in the places where these effects are tolerable or manageable. A few possible solutions for tackling all SR related problems as well as vacuum design are discussed in the paper in details.
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
STFC/DL, Daresbury, Warrington, Cheshire
The University of Liverpool, Liverpool
Cockcroft Institute, Warrington, Cheshire
BINP SB RAS, Novosibirsk
A 374-m long wiggler section is a key part of ILC damping ring that should alloy reaching a low beam emittance for the ILC experiment. Synchrotron radiation generated by the beam in the wigglers should be absorbed by different components of vacuum vessel, including specially designed absorbers. The optimisation of the mechanical design, vacuum system and anti-e-cloud mitigation requires accurate calculation of the SR power distribution. The angular power distribution from a single wiggler was calculated with in-house developed software. Then the superposition of SR from all wigglers allows calculating power distribution for all components along the wiggler section and the downstream straight section.
Cockcroft Institute, Warrington, Cheshire
STFC/DL, Daresbury, Warrington, Cheshire
The University of Liverpool, Liverpool
The longitudinal wake fields have been calculated by using 3D code, CST Particle Studio, for a number of different vacuum chamber components of the 6.4 km ILC damping ring design. Based on the results, studies of bunch lengthening and single-bunch instabilities have been carried out. Bunch lengthening from a particle tracking code are compared with results from numerical solution of the Haissinski equation. The tracking code is used to predict the threshold for single-bunch instabilities.
Cockcroft Institute, Warrington, Cheshire
A new lattice design for the ILC damping ring has been developed since the beginning of 2008 as a lower cost alternative to the previous OCS6 design. The lattices for the electron and positron damping rings are identical, and are designed to provide an intense, 5 GeV beam with low emittance at extraction. The latest design, presented in this paper, provides sufficient dynamic aperture for the large positron beam at injection. The lattice also meets the engineering requirements for arrangement of the positron ring directly above the electron ring in the same tunnel, using common girders for the magnets in the two rings, but with the beams circulating in opposite directions.
Cockcroft Institute, Warrington, Cheshire
The University of Liverpool, Liverpool
One of the major challenges for the International Linear Collider (ILC) damping rings is the attainment of the 2 pm vertical emittance specification. To achieve such an ultra-low vertical emittance a highly effective diagnostics and correction system is needed. However, since both BPMs and correctors have also negative impacts on the design (cost, complexity, impedance), it is important to understand how the number and locations of both these components affect the correction. In this paper we present the results of simulations for the Technical Design Phase baseline damping rings lattice (DCO4), aimed at understanding the effectiveness of orbit, dispersion, and coupling correction for different design and operation scenarios.
Brunel University, Middlesex
STFC/RAL, Chilton, Didcot, Oxon
The University of Liverpool, Liverpool
The Non Scaling Fixed Field Alternating Gradient EMMA has a compact linear lattice. Effect of Fringe Field on the beam has to be studied carefully. A numerical magnetic field map is generated by magnet measurements or magnet design softwares. We developed a technique that produces from the numerical field map, a dynamical map for a particle travelling in the entire EMMA cell for a reference energy without acceleration. Since the beam dynamics change with energy, a set of maps have been produce with different reference energies between 10 and 20MeV. For each reference energy, simulated tune and time of flight (TOF) have been compared with results in Zgoubi - tracking directly through numerical field map. The range of validity of a single map has been investigated by tracking particle with large energy deviation. From that, a sensible acceleration scheme has been implemented.
yoel.giboudot@stfc.ac.uk
Cockcroft Institute, Warrington, Cheshire
Lancaster University, Lancaster
The University of Liverpool, Liverpool
CLIC will need of order 10 to the 14 positrons per second to achieve its specified luminosity. For such a challenge, an undulator based scheme has been proposed as one of the options for the positron source. As CLIC may operate over a wide range of energy (from 0.5 TeV to 3 TeV), there is a large margin for us to push the performance of the whole system to be more efficient. We report on the undulator parameters and optimization of components of the source such as conversion target, AMD, solenoid and capture RF for different operational scenarios. In addition to maximizing the positron yield the polarization of the positron beam are also considered.
The University of Liverpool, Liverpool
BPMs capable of high resolution turn-by-turn bunch position measurements are becoming increasingly widely used in electron storage rings. Analysis of the data from a set of such BPMs following the excitation of a coherent betatron oscillation can yield useful information for tuning the optics and improving machine performance. This approach to optics measurement has the benefits that the data collection is very fast, and analysis can be local, so that application is as easy for a large ring as for a small one. Here, we describe a technique for using turn-by-turn BPM data to determine lattice functions that describe the local coupling in a storage ring; this may be helpful, for example, for achieving low vertical emittance. We discuss the principles of the technique, give some examples, and discuss possible limitations arising from BPM gain and coupling errors.
Brunel University, Middlesex
The University of Liverpool, Liverpool
The Non Scaling Fixed Field Alternating Gradient (NS-FFAG) EMMA accelerator has a purely linear lattice and thus allows important tune variation. The crossing of resonances during acceleration is a key characteristic of the beam dynamics. An accurate measurement of the tune is therefore mandatory. However commonly used measurement techniques requires the beam to perform an important number of turns in the machine. Simulations have shown that fast decoherence of the beam requires the study of another measurement technique. The model independent analysis (MIA) has been investigated. The singular value decomposition (SVD) of a matrix composed of simulated BPMs reading of various bunches trajectories gives a description of the optics function at each Beam Position Monitor. Including misalignment errors and electronic noise, an accurate value of the tune has been derived from statistical treatment repeating this process few hundreds of time.
yoel.giboudot@stfc.ac.uk