Feedback response in the CLIC main linac to transverse and longitudinal dynamic imperfections

In the main linac of the Compact Linear Collider (CLIC), longitudinal and transverse dynamic imperfections, such as RF phase jitter, variation of bunch length and movements of elements, can result in significant luminosity loss. The responses of local trajectory feedbacks to these imperfections are studied in this paper

Static beam-based alignment of the RF structures in the CLIC main linac

In the Compact Linear Collider (CLIC), it is planned to use an active micro-mover system in order to align the components of the main linac with an accuracy in the micrometre range. The active alignment system has already been successfully tested in CTF2. The effectiveness of such an alignment system is simulated for different hardware configurations and correction algorithms

Dynamic Effects in the Main Linac of CLIC

The main linac of CLIC is very sensitive to jitters of the quadrupoles in transverse position and strength. Drifts due to the ground motion for example, have also to be considered, as well as errors on the amplitude and phase of the accelerating RF. This paper investigates the impact these dynamic effects have on the emittance and the luminosity of the collider, and the possibility to use feedbacks to correct the ground motion effect

A Mean Reverting Stochastic Process (MRSP) using an AR(n) Model and a Kalman Filter for Generating Intravalues for the Daily DJIA Time Series

This paper presents a model for generating intravalues of time-series. The model uses a mean reverting stochastic process (MRSP). The deterministic or mean part of the process is forecasted by an autoregressive of order n, AR(n), model. The unobservable AR(n) coefficients are calculated by a Kalman Filter using n time series observations. The stochastic part of the process is a Brownian motion multiplied by a volatility term. Measures of the Kalman filter covariance matrix along with the process itself are used to capture the volatility dynamics for the intravalues of the time-series. The MRSP model also provides for the evolution of the intravalues of the time series. Experimental results are presented demonstrating the applicability of the model using daily data from the Dow Jones Industrial Average (DJIA) time series

Simulation Package based on Placet

The program PLACET is used to simulate transverse and longitudinal beam effects in the main linac, the drive-beam accelerator and the drive-beam decelerators of CLIC, as well as in the linac of CTF3. It provides different models of accelerating and decelerating structures, linear optics and thin multipoles. Several methods of beam-based alignment, including emittance tuning bumps and feedback, and different failure modes can be simulated. An interface to the beam-beam simulation code GUINEA-PIG exists. Currently, interfaces to MAD and TRANSPORT are under development and an extension to transfer lines and bunch compressors is also being made. In the future, the simulations will need to be performed by many users, which requires a simplified user interface. The paper describes the status of PLACET and plans for the futu

A Probabilistic Model for Evaluating the Operational Cost of PKI-based Financial Transactions

Abstract. The use of PKI in large scale environments suffers some inherent problems concerning the options to adopt for the optimal cost-centered operation of the system. In this paper a Markov based probability model has been applied and a performability indicator has been introduced for assisting the evaluation of the operational cost of the system in a decision support process. Considering the unavailability of the Certification Authority server, three different strategies have been evaluated for determining the optimal one

CLIC simulations from the start of the linac to the interaction point

Simulations for linear colliders are traditionally performed separately for the different sub-systems, like damping ring, bunch compressor, linac, and beam delivery. The beam properties are usually passed from one sub-system to the other via bunch charge, RMS transverse emittances, RMS bunch length, average energy and RMS energy spread. It is implicitly assumed that the detailed 6D correlations in the beam distribution are not relevant for the achievable luminosity. However, it has recently been shown that those correlations can have a strong effect on the beam-beam interaction. We present first results on CLIC simulations that integrate linac, beam delivery, and beam-beam interaction. These integrated simulations also allow a better simulation of time-dependent effects, like ground perturbations and interference between several beam-based feedbacks

Status of the CLIC study on magnet stabilisation and time-dependent luminosity

The nanometer beam size at the CLIC interaction point imposes magnet vibration tolerances that range from 0.2 nm to a few nanometers. This is well below the floor vibra-tion usually observed. A test stand for magnet stability was set-up at CERN in the immediate neighborhood of roads, operating accelerators, manual shops, and regular office space. It was equipped with modern stabilization tech-nology. First results are presented, demonstrating signif-icant damping of floor vibration. CLIC quadrupoles have been stabilized vertically to an rms motion of (0.9 ± 0.1) n above 4 Hz, or (1.3 ± 0.2) nm with a nominal flow of cooling water. For the horizontal and longitudinal directions respectively, a CLIC quadrupole was stabilized to (0.4 ± 0.1) nm and (3.2 ± 0.4) nm

HyperCP: A high-rate spectrometer for the study of charged hyperon and kaon decays

The HyperCP experiment (Fermilab E871) was designed to search for rare phenomena in the decays of charged strange particles, in particular CP violation in $\Xi$ and $\Lambda$ hyperon decays with a sensitivity of $10^{-4}$. Intense charged secondary beams were produced by 800 GeV/c protons and momentum-selected by a magnetic channel. Decay products were detected in a large-acceptance, high-rate magnetic spectrometer using multiwire proportional chambers, trigger hodoscopes, a hadronic calorimeter, and a muon-detection system. Nearly identical acceptances and efficiencies for hyperons and antihyperons decaying within an evacuated volume were achieved by reversing the polarities of the channel and spectrometer magnets. A high-rate data-acquisition system enabled 231 billion events to be recorded in twelve months of data-taking.Comment: 107 pages, 45 Postscript figures, 14 tables, Elsevier LaTeX, submitted to Nucl. Instrum. Meth.

The CLIC Study of Magnet Stability and Time-dependent Luminosity Performance

The present parameters of the CLIC study require the collision of small emittance beams with a vertical spot size of 1 nm. The tolerances on vertical quadrupole vi-bration (above a few Hz) are as small as a few nm in the linac and most of the Final Focus. The final focusing quadrupole has a stability requirement of 4 nm in the horizontal and 0.2 nm in the vertical direction. Those tol-erances can only be achieved with the use of damped support structures for CLIC. A study has been set-up at CERN to explore the application of stabilization devices from specialized industry and to predict the time-dependent luminosity performance for CLIC. The results will guide the specification of required technological im-provements and will help to verify the feasibility of the present CLIC parameters