Physics at TESLA

The physics at a 500-800 GeV electron positron linear collider, TESLA, is reviewed. The machine parameters that impact directly on the physics are discussed and a few key performance goals for a detector at TESLA are given. Emphasis is placed on precision measurements in the Higgs and top sectors and on extrapolation to high energy scales in the supersymmetric scenario.Comment: Talk presented at Lake Louise Winter Institute 2001. 7 pages, 2 figure

Precision GMSB at a Linear Collider

We simulate precision measurements of gauge-mediated supersymmetry breaking (GMSB) parameters at a 500 GeV e+e- linear collider in the scenario where a neutralino is the next-to-lightest supersymmetric particle. Information on the supersymmetry breaking and the messenger sectors of the theory is extracted from the measured sparticle mass spectrum and neutralino lifetime.Comment: LaTeX + sprocl.sty + epsf.sty, 6 pages, 3 figures (5 eps files

Measuring Gauge-Mediated SuperSymmetry Breaking Parameters at a 500 GeV e+e- Linear Collider

We consider the phenomenology of a class of gauge-mediated supersymmetry (SUSY) breaking (GMSB) models at a e+e- Linear Collider (LC) with c.o.m. energy up to 500 GeV. In particular, we refer to a high-luminosity (L ~ 3 x 10^34 cm^-2 s^-1) machine, and use detailed simulation tools for a proposed detector. Among the GMSB-model building options, we define a simple framework and outline its predictions at the LC, under the assumption that no SUSY signal is detected at LEP or Tevatron. Our focus is on the case where a neutralino (N1) is the next-to-lightest SUSY particle (NLSP), for which we determine the relevant regions of the GMSB parameter space. Many observables are calculated and discussed, including production cross sections, NLSP decay widths, branching ratios and distributions, for dominant and rare channels. We sketch how to extract the messenger and electroweak scale model parameters from a spectrum measured via, e.g. threshold-scanning techniques. Several experimental methods to measure the NLSP mass and lifetime are proposed and simulated in detail. We show that these methods can cover most of the lifetime range allowed by perturbativity requirements and suggested by cosmology in GMSB models. Also, they are relevant for any general low-energy SUSY breaking scenario. Values of c*tau_N1 as short as 10's of microns and as long as 10's of metres can be measured with errors at the level of 10% or better after one year of LC running with high luminosity. We discuss how to determine a narrow range (<~ 5%) for the fundamental SUSY breaking scale sqrt(F), based on the measured m_N1, c*tau_N1. Finally, we suggest how to optimise the LC detector performance for this purpose.Comment: 56 pages, 32 figures (48 eps files), LaTeX + epsf.sty + colordvi.sty. Revision v2: minor changes/additions, version to be published in EPJ

Extracting GMSB Parameters at a Linear Collider

Assuming gauge-mediated supersymmetry breaking, we simulate precision measurements of fundamental parameters at a 500 GeV e+e- linear collider in the scenario where a neutralino is the next-to-lightest supersymmetric particle. Information on the supersymmetry breaking and the messenger sectors of the theory is extracted from realistic fits to the measured mass spectrum of the Minimal Supersymmetric Model particles and the next-to-lightest supersymmetric particle lifetime.Comment: 6 pages, LaTeX + epsf.sty, 3 figure

Muon Background Reduction in CLIC

We report on a study concerning the reduction of muon backgrounds in CLIC using magnetised iron.Comment: Proceedings of the International Workshop on future Linear Colliders 2011 (LCWS11), Granada, Spain. 4 pages, 4 figure

Real-time video scene analysis with heterogeneous processors

Field-Programmable Gate Arrays (FPGAs) and General Purpose Graphics Processing Units (GPUs) allow acceleration and real-time processing of computationally intensive computer vision algorithms. The decision to use either architecture in any application is determined by task-specific priorities such as processing latency, power consumption and algorithm accuracy. This choice is normally made at design time on a heuristic or fixed algorithmic basis; here we propose an alternative method for automatic runtime selection. In this thesis, we describe our PC-based system architecture containing both platforms; this provides greater flexibility and allows dynamic selection of processing platforms to suit changing scene priorities. Using the Histograms of Oriented Gradients (HOG) algorithm for pedestrian detection, we comprehensively explore algorithm implementation on FPGA, GPU and a combination of both, and show that the effect of data transfer time on overall processing performance is significant. We also characterise performance of each implementation and quantify tradeoffs between power, time and accuracy when moving processing between architectures, then specify the optimal architecture to use when prioritising each of these. We apply this new knowledge to a real-time surveillance application representative of anomaly detection problems: detecting parked vehicles in videos. Using motion detection and car and pedestrian HOG detectors implemented across multiple architectures to generate detections, we use trajectory clustering and a Bayesian contextual motion algorithm to generate an overall scene anomaly level. This is in turn used to select the architectures to run the compute-intensive detectors for the next frame on, with higher anomalies selecting faster, higher-power implementations. Comparing dynamic context-driven prioritisation of system performance against a fixed mapping of algorithms to architectures shows that our dynamic mapping method is 10% more accurate at detecting events than the power-optimised version, at the cost of 12W higher power consumption

Laser wire emittance measurement line at CLIC

A precise measurement of the transverse beam size and beam emittances upstream of the final focus is essential for ensuring the full luminosity at future linear colliders. A scheme for the emittance measurements at the RTML line of the CLIC using laser-wire beam profile monitors is described. A lattice of the measurement line is discussed and results of simulations of statistical errors and of their impact on the accuracy of the emittance reconstruction are given. Laser wire systems suitable for CLIC and their main characteristics are discussed.Postprint (published version

Micron-scale laser-wire scanner for the KEK Accelerator Test Facility extraction line

A laser-wire transverse electron beam size measurement system has been constructed and operated at the Accelerator Test Facility (ATF) extraction line at KEK. The construction of the system is described in detail along with the environment of the ATF related to the laser wire. A special set of electron beam optics was developed to generate an approximately 1 mu m vertical focus at the laser-wire location. The results of our operation at the ATF extraction line are presented, where a minimum rms electron beam size of 4: 8 +/- 0: 3 mu m was measured, and smaller electron beam sizes can be measured by developing the method further. The beam size at the laser-wire location was changed using quadrupoles and the resulting electron beam size measured, and vertical emittance extracted