Showing papers by "Claude Leroy published in 2007"

Particle interaction and displacement damage in silicon devices operated in radiation environments

Abstract: Silicon is used in radiation detectors and electronic devices. Nowadays, these devices achieving submicron technology are parts of integrated circuits of large to very large scale integration (VLSI). Silicon and silicon-based devices are commonly operated in many fields including particle physics experiments, nuclear medicine and space. Some of these fields present adverse radiation environments that may affect the operation of the devices. The particle energy deposition mechanisms by ionization and non-ionization processes are reviewed as well as the radiation-induced damage and its effect on device parameters evolution, depending on particle type, energy and fluence. The temporary or permanent damage inflicted by a single particle (single event effect) to electronic devices or integrated circuits is treated separately from the total ionizing dose (TID) effect for which the accumulated fluence causes degradation and from the displacement damage induced by the non-ionizing energy-loss (NIEL) deposition. Understanding of radiation effects on silicon devices has an impact on their design and allows the prediction of a specific device behaviour when exposed to a radiation field of interest.

Charge collection from proton and alpha particle tracks in silicon pixel detector devices

Abstract: The lateral spread of charge carriers under the influence of the electric field in a pixellated silicon detector hit by a heavy charged particle, such as a proton or an alpha-particle, causes a sharing of the charge between the electrodes and many pixels have a signal The results of the charge sharing effect measured in the Medipix2 and Timepix pixel detectors of 300 mum thicknesses is shown as a function of particle energy and applied bias voltage A model describing the effects of funneling, plasma and diffusion on the charge collection and its sharing will be also presented Using Timepix, it is possible to measure directly the quantity of charge deposited in each pixel within the cluster and to follow changes in charge collection as a function of collection time This allows 3D-visualization of individual tracks of charged particles in silicon with Timepix

NUCLEAR PHYSICS METHODS AND ACCELERATORS IN BIOLOGY AND MEDICINE: Fourth International Summer School on Nuclear Physics Methods and Accelerators in Biology and Medicine

Abstract: These proceedings are a collection of manuscripts of the lectures given at the Fourth International Summer School on Nuclear Physics Methods and Accelerators in Biology and Medicine. They provide a broad up-to-date review of the current knowledge and methods of Nuclear Physics and Particle Accelerators and their applications in medicine and biology. The material here will be of huge interest to university students of engineering, physics, medicine, and biology.

Modified Hecht model qualifying radiation damage in standard and oxygenated silicon detectors from 10 MeV protons

Abstract: The Hecht model describes the charge collection efficiency of semiconductor detectors using the mean free path of the charge carriers. While the fits to data are very good for non-irradiated detectors, modifications to the model are necessary to take into account the structural changes in the detectors induced by their exposure to high particle fluences. A modified model is presented. In this model, the mean free path depends on the shape of the electric field and on the charge carrier lifetimes. The lifetimes were measured experimentally from the front- and back-illuminations of the detectors by 660 nm laser light and by α particles from an 241 Am source. This new Hecht model was successfully fitted to alpha and beta charge collection efficiencies of standard and oxygenated silicon detectors after their irradiation by 10 MeV protons with fluences varying from 10 11 to 3×10 14 p/cm 2 .