An Electro - Optical Test System for Optimising Operating Conditions of CCD sensors for LSST

We describe the commissioning of a system which has been built to investigate optimal operation of CCDs for the LSST telescope. The test system is designed for low vibration, high stability operation and is capable of illuminating a detector in flat-field, projected spot, projected pattern and Fe-55 configurations. We compare and describe some considerations when choosing a gain calibration method for CCDs which exhibit the brighter-fatter effect. An optimisation study on a prototype device of gain and full well with varying back substrate bias and gate clock levels is presented

Charge Collection in Silicon Imaging Sensors

The subject of this thesis is the analysis of instrumental effects caused by the interaction between collected signal charge and electric fields within precision CCD imaging sensors typically used for astronomy. These phenomena cause aberrations in the measured spatial distribution of subsequently collected signal, which may present a major error for upcoming astronomy projects which rely heavily on accurately determining shapes of compact sources. Examples are the Large Synoptic Survey Telescope and the Euclid space telescope. The size of dynamic collection effects may be subtly affected by the operating conditions and design parameters of the device. Dynamic charge collection effects differ in origin from many other errors introduced by imaging detectors in that they are attributable to changes in the confinement of charge carriers during the collection phase of operation, rather than the readout phase. The fact that the exact aberration implied by dynamic charge collection effects depends exactly on the incident light field’s spatial distribution also makes them comparatively difficult to correct for. A method of physically modelling charge collection within the detector using analytical solutions to Poisson’s equation is described, which is shown to qualitatively reproduce many features of measured dynamic charge collection effects. Since the model is derived from device physics, it differs in approach in a complementary way from previous efforts which are empirically based. Experimental charge collection measurements from two different CCDs both affected by dynamic collection effects are presented, and shown in large part to be consistent with the predictions from the theoretical model

Modelling and testing the x-ray performance of CCD and CMOS APS detectors using numerical finite element simulations

Pixellated monolithic silicon detectors operated in a photon-counting regime are useful in spectroscopic imaging applications. Since a high energy incident photon may produce many excess free carriers upon absorption, both energy and spatial information can be recovered by resolving each interaction event. The performance of these devices in terms of both the energy and spatial resolution is in large part determined by the amount of diffusion which occurs during the collection of the charge cloud by the pixels. Past efforts to predict the X-ray performance of imaging sensors have used either analytical solutions to the diffusion equation or simplified monte carlo electron transport models. These methods are computationally attractive and highly useful but may be complemented using more physically detailed models based on TCAD simulations of the devices. Here we present initial results from a model which employs a full transient numerical solution of the classical semiconductor equations to model charge collection in device pixels under stimulation from initially Gaussian photogenerated charge clouds, using commercial TCAD software. Realistic device geometries and doping are included. By mapping the pixel response to different initial interaction positions and charge cloud sizes, the charge splitting behaviour of the model sensor under various illuminations and operating conditions is investigated. Experimental validation of the model is presented from an e2v CCD30-11 device under varying substrate bias, illuminated using an Fe-55 source

Technological development of the OGRE focal plane array

The Off-plane Grating Rocket Experiment (OGRE) is a high resolution soft X-ray spectrometer sub-orbital rocket payload designed as a technology development platform for three low Technology Readiness Level (TRL) components. The incident photons will be focused using a light-weight, high resolution, single-crystal silicon optic. They are then dispersed conically according to wavelength by an array of off-plane gratings before being detected in a focal plane camera comprised of four Electron Multiplying Charge-Coupled Devices (EM-CCDs). While CCDs have been extensively used in space applications; EM-CCDs are seldom used in this environment and even more rarely for X-ray photon counting applications, making them a potential technology risk for larger scale X-ray observatories. This paper will discuss the reasons behind choosing EM-CCDs for the focal plane detector and the developments that have been recently made in the prototype camera electronics and thermal control system

Models for dynamic correlated charge collection effects in thick CCDs

Dynamic charge collection effects in thick CCDs have received interest in recent years, due to the performance implications for both ground and space based precision optical astronomy. The phenomena manifest as the "brighter - fatter" effect in Point Spread Function (PSF) measurements, and nonlinearity and signal dependence in spatial autocorrelation and photon transfer measurements. In this paper we present validation results from simple, analytically based predictive models for this effect, using an e2v CCD250. The model is intended to provide estimations for predicting device performance based on design parameters

Development of the X-ray camera for the OGRE sub-orbital rocket

Current theories regarding the matter composition of the universe suggest that half of the expected baryonic matter is missing. One region this could be residing in is intergalactic filaments which absorb strongly in the X-ray regime. Present space based technology is limited when it comes to imaging at these wavelengths and so new techniques are required. The Off-Plane Grating Rocket Experiment (OGRE) aims to produce the highest resolution spectrum of the binary star system Capella, a well-known X-ray source, in the soft X-ray range (0.2keV to 2keV). This will be achieved using a specialised payload combining three low technology readiness level components placed on-board a sub-orbital rocket. These three components consist of an array of large format off-plane X-ray diffraction gratings, a Wolter Type 1 mirror made using single crystal silicon, and the use of EM-CCDs to capture soft X-rays. Each of these components have been previously reviewed with OGRE being the first project to utilise them in a space observation mission. This paper focuses on the EM-CCDs (CCD207-40 by e2v) that will be used and their optimisation with a camera purposely designed for OGRE. Electron Multiplying gain curves were produced for the back-illuminated devices at -80 degrees Celsius. Further tests which will need to be carried out are discussed and the impact of the OGRE mission on future projects mentioned

The institutional framework for doing sports business: principles of EU competition policy in sports markets

The competition rules and policy framework of the European Union represents an important institutional restriction for doing sports business. Driven by the courts, the 2007 overhaul of the approach and methodology has increased the scope of competition policy towards sports associations and clubs. Nowadays, virtually all activities of sports associations that govern and organize a sports discipline with business elements are subject to antitrust rules. This includes genuine sporting rules that are essential for a league, championship or tournament to come into existence. Of course, 'real' business or commercial activities like ticket selling, marketing of broadcasting rights, etc. also have to comply with competition rules. Regulatory activities of sports associations comply with European competition rules if they pursuit a legitimate objective, its restrictive effects are inherent to that objective and proportionate to it. This new approach offers important orientation for the strategy choice of sports associations, clubs and related enterprises. Since this assessment is done following a case-by-case approach, however, neither a blacklist of anticompetitive nor a whitelist of procompetitive sporting rules can be derived. Instead, conclusions can be drawn only from the existing case decisions - but, unfortunately, this leaves many aspects open. With respect to business activities, the focus of European competition policy is on centralized marketing arrangements bundling media rights. These constitute cartels and are viewed to be anticompetitive in nature. However, they may be exempted from the cartel prohibition on efficiency and consumer benefits considerations. Here, a detailed list of conditions exists that centralized marketing arrangements must comply with in order to be legal. Although this policy seems to be well-developed at first sight, a closer look at the decision practice reveals several open problems. Other areas of the buying and selling behavior of sports associations and related enterprises are considerably less well-developed and do not provide much orientation for business