Extreme ultraviolet detection using AlGaN-on-Si inverted Schottky photodiodes

We report on the fabrication of aluminum gallium nitride (AlGaN) Schottky diodes for extreme ultraviolet (EUV) detection. AlGaN layers were grown on silicon wafers by molecular beam epitaxy with the conventional and inverted Schottky structure, where the undoped, active layer was grown before or after the n-doped layer, respectively. Different current mechanisms were observed in the two structures. The inverted Schottky diode was designed for the optimized backside sensitivity in the hybrid imagers. A cut-off wavelength of 280 nm was observed with three orders of magnitude intrinsic rejection ratio of the visible radiation. Furthermore, the inverted structure was characterized using a EUV source based on helium discharge and an open electrode design was used to improve the sensitivity. The characteristic He I and He II emission lines were observed at the wavelengths of 58.4 nm and 30.4 nm, respectively, proving the feasibility of using the inverted layer stack for EUV detectio

The PROBA2 satellite on the hunt for solar eruptions

PROBA2 is an ESA micro-satellite that is being prepared for launch in 2009. Its primary goal is the demonstration of new technologies in the space environment. Its secondary goal is the exploitation of its scientific payload. PROBA2 carries an ambitious suite of both in-situ and remote sensing instruments for monitoring space weather, despite the modest onboard resources inherent to a micro-satellite. Both the spacecraft and the remote sensing instruments are largely developed within Belgium. In this paper we briefly overview the spacecraft and its payload. We focus on how the PROBA2 mission connects to the Belgian space weather community and pay particular attention on the detector technology demonstrated onboard PROBA2.status: publishe

EUV high resolution imager on-board Solar Orbiter: optical design and detector performances.

The EUV high resolution imager (HRI) channel of the Extreme Ultraviolet Imager (EUI) on-board Solar Orbiter will observe the solar atmospheric layers at 17.4 nm wavelength with a 200 km resolution. The HRI channel is based on a compact two mirrors off-axis design. The spectral selection is obtained by a multilayer coating deposited on the mirrors and by redundant Aluminum filters rejecting the visible and infrared light. The detector is a 2k x 2k array back-thinned silicon CMOS-APS with 10 µm pixel pitch, sensitive in the EUV wavelength range. Due to the instrument compactness and the constraints on the optical design, the channel performance is very sensitive to the manufacturing, alignments and settling errors. A trade-off between two optical layouts was therefore performed to select the final optical design and to improve the mirror mounts. The effect of diffraction by the filter mesh support and by the mirror diffusion has been included in the overall error budget. Manufacturing of mirror and mounts has started and will result in thermo-mechanical validation on the EUI instrument structural and thermal model (STM). Because of the limited channel entrance aperture and consequently the low input flux, the channel performance also relies on the detector EUV sensitivity, readout noise and dynamic range. Based on the characterization of a CMOS-APS back-side detector prototype, showing promising results, the EUI detector has been specified and is under development. These detectors will undergo a qualification program before being tested and integrated on the EUI instrument

VOLT Valve: Applying the Frugal Innovation in a Green Touchless Low-Tech Solution

In their innovative development strategy, the third world countries should escape the sheep-like behaviour by following the same pathway as the developed western countries. Because they don’t have the same historical, geopolitical and social factors. There's a lot of truth behind Bruce Lee's well-known quote: “Using no way as way; having no limitation as limitation” by using practical technique with flexibility and reliability instead of theoretical and rigid method. The Frugal Innovation is a good demonstration of this practical way with the ability to “do more with less” [1-2] by creating more business and social value while minimizing the use of diminishing resources such as water, energy and funding. Within this context, the aim of the VOLT valve, where VOLT is the abbreviation of “Valve Opening with Low Tech”, is to propose an autonomous, low tech, eco-efficiency and compact product. This innovation have five distinct aspects that can be resumed in two words, WLoG NoTS (Water, Low, Green, No Touch and Social Technology) which is reflecting a homophony with “ Have nots “ who need to meet their energy and water needs in a quick and smart way

Place de la splénectomie dans la prise en charge de l’hypertension portale non cirrhotique: à propos de 3 cas

L’hypertension portale non cirrhotique est une affection décrite pour la première fois par Guido BANTI en 1898 comme une affection associant une hypertension portale avec splénomégalie et anémie sur foie sain. Le diagnostic repose sur l’échographie abdominale, la splénoportographie et la biopsie hépatique. Le but de notre travail est d’évaluer la place de la splénectomie dans l’hypertension portale non cirrhotique à travers une étude rétrospective portant sur 3 malades dont 2 femmes et un homme pris en charge dans notre formation entre Janvier 2010 et Septembre 2016. Le diagnostic de l’hypertension portale idiopathique a été basé sur les critères suivants : une hypertension portale, la présence des varices oesophagiènnes avec une splénomégalie, l’absence de cirrhose ou d’autres affections hépatiques responsables de l’hypertension portale. La splénectomie a été réalisée chez les 3 malades. L’évolution après la splénectomie était marquée par la normalisation des signes cliniques, radiologiques et biologiques de cette affection, avec absence de récidive des varices oesophagiennes. La splénectomie associée à la ligature des varices oesophagiennes pourraient être suffisantes pour traiter ce syndrome et surtout ses conséquences sans avoir recours à une dérivation spléno-rénale