The presence of turbulence in astrophysical magnetic fields can have a significant effect on the diffusion of particles and, therefore, should be taken into account when performing simulations involving particle propagation. After reviewing the constructionof the turbulent magnetic field component, we incorporate this feature in two separate projects. In the first, we consider the possible source(s) of hadronic cosmic rays thought to be responsible for the diffuse TeV gamma-ray emission in the vicinity ofthe Galactic center. Assuming a completely turbulent magnetic field with an average strength of 10-100microG, we find that relativistic protons do not travel far enough to produce gamma-rays spatially correlated with the giant molecular clouds, as seen by HESS,when injected into the interstellar medium by a single point source, such as the supermassive black hole Sagittarius A*. Increasing the number of point sources to five does improve the longitudinal extent of the emission but either shows only weak correlation with the molecular gas or highlights the source positions - both pictures areinconsistent with HESS observations. We conclude that protons must be accelerated throughout the Galactic center region via e.g. a second-order Fermi process in order to reproduce the HESS gamma-ray map if the magnetic field there is completely turbulent. Secondly, we examine the possible link between the asymmetric 511keV electron-positron annihilation emission from the inner Galactic disk and hard low mass X-ray binaries (LMXBs). Three different magnetic field configurations were considered: a completely turbulent field, a field in which the turbulent component has equal energy density as the mean component, and a strongly ordered field with little turbulence. Assuming the environment around each LMXB system is the same, we find that the LMXBs alone cannot account for all the positrons necessary to sufficiently fill the region regardless of the particular magnetic field structure chosen. Another transport mechanism (e.g. a galactic wind) in addition to the diffusive motion caused by the magnetic field fluctuations and/or allowing the LMXBs to be embedded in different phases of the interstellar medium is needed for the LMXB picture to remain a viable possibility.

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The first measurement of the ratio of the W and Z cross sections in association with a single jet, known as the R_{Jets} measurement, is presented. The measurement was performed using 33pb^-1 of integrated luminosity, recorded during the year 2010 by the ATLAS detector at the LHC. At this time the LHC was operating at a center-of-mass energy of 7 TeV. The measurement is made as a function of the threshold on the jet transverse momentum, from 30 GeV up to a value of 200 GeV. The motivation for this measurement is outlined in terms of providing a stringent test of the Standard Model of particle physics, as well as a model independent tool for searching for new physics. Data driven tools are developed to perform the measurement and their performance is discussed. The result of the measurement is compared with the predictions of Next-to-Leading order perturbative QCD and found to be in good agreement over the entire range of transverse momenta considered.

An Interaction Point Collision Feedback System is necessary to achieve design luminosity at the future International Linear Collider (ILC). This is proposed to include a stripline beam position monitor (BPM) positioned 3 m from the Interaction Point (IP). The BPM is required to be able to measure the position of the outgoing electron or positron beam with a resolution of 1 m. Prototype feedback systems have been built and tested at the Next Linear Collider Test Accelerator (NLCTA) at the Stanford Linear Accelerator Center in the USA (SLAC) and also at the Accelerator Test Facility (ATF) at the High Energy Research Laboratory in Japan (KEK). The successful correction of position osets is demonstrated with the lowest latency achieved 24 ns, the best position resolution 4 m and the best correction ratio 23:1. To make the feedback system a more powerful tool, a digital processor is added. It raises the total latency of the feedback system to 140 ns. Its ability to perform algorithms is demonstrated with charge normalisation. Preliminary results indicate a resolution of 8 m and correction ratio 7:1. Backgrounds at the ILC comprise mainly electron-positron pairs from the beam-beam interaction. For the high luminosity 1TeV accelerator parameters, 105 pairs are produced per bunch crossing. This is the worst case for ILC pair backgrounds. These pairs produce 5 105 particle hits on a stripline of the IP feedback BPM. In two experiments at End Station A (ESA) at SLAC, a stripline BPM was exposed to secondary particle backgrounds to determine if the particle hits degraded the ability of the stripline BPM to resolve micron-level position osets. The experiments agree that the worst ILC pair backgrounds degrade the resolution by less than 8.5 nm (95% confidence level). It is concluded that micron-level resolution will not be aected by the ILC pair backgrounds. Studies of stripline signals caused by backgrounds led to the development of a GEANT3- based tool that could predict the signals. The prediction tool was tested against one of the experiments at ESA and used to predict the signals on the ILC feedback BPM striplines. The results confirm that the ILC pair backgrounds do not produce micron-level errors in position measurement, indicating that the degradation in resolution by the worst pair backgrounds expected was under 13 nm.