Search

Active edge p-on-p silicon pixel detectors with thickness of 100 μ m were fabricated on 150 mm float zone silicon wafers at VTT. By combining measured results and TCAD simulations, a detailed study of electric field distributions and charge collection performances as a function of applied voltage in a p-on-p detector was carried out. A comparison with the results of a more conventional active edge p-on-n pixel sensor is presented. The results from 3D spatial mapping show that at pixel-to-edge distances less than 100 μ m the sensitive volume is extended to the physical edge of the detector when the applied voltage is above full depletion. The results from a spectroscopic measurement demonstrate a good functionality of the edge pixels. The interpixel isolation above full depletion and the breakdown voltage were found to be equal to the p-on-n sensor while lower charge collection was observed in the p-on-p pixel sensor below 80 V. Simulations indicated this to be partly a result of a more favourable weighting field in the p-on-n sensor and partly of lower hole lifetimes in the p-bulk. [ABSTRACT FROM AUTHOR]

Abstract: An X-ray micro-radiographic system based on the Medipix2 semiconductor pixel detector for dynamic high spatial resolution and for high contrast imaging has been developed. Our system is based on a micro-focus and nano-focus X-ray tube and the hybrid single-photon counting silicon pixel detector Medipix2 (matrix 256×256sq. pixels of 55μm pitch). This compact table-top system stands promising as a new tool in the field of small animal imaging as well as in the in-vivo observation of dynamic processes inside living organisms. The main advantages of these Medipix2 pixel detectors include: high sensitivity to low-energy X-ray photons; position sensitive and noiseless single-photon detection with preselected photon energies; single-quantum counting in each pixel performed by digital counter (therefore there is no dark current); digital integration (providing unlimited dynamic range and absolute linearity in device response to number of photons, high sensitivity and high contrast); real-time digital information, high-speed digital communication and data transfer. We improve the picture quality with the help of statistical data analysis and extended the calibration of individual pixels response. 2D and 3D radiographic images of samples demonstrate the potential and applicability of our system for precise in-vivo X-ray high-resolution dynamic diagnostic and biological studies. Obtained results are shown on small animal and organic samples. [Copyright &y& Elsevier]