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In this work we have investigated the functioning of high resistivity amorphous silicon and silicon-rich nitride layers as a protection against discharges in Micro-Patterned Gaseous Detectors (MPGDs).When the anode is protected by a high resistivity layer, discharge signals are limited in charge. A signal reduction is expected when the layers are too thick; simulations presented in this paper indicate that layer supto 10 mm thick can be applied without significantly degrading the detector performance. Layers of amorphous silicon and silicon-rich nitride have been deposited on top of Timepix and Medipix 2chips in GridPix detectors; with this, chips survive naturally occurring as well as intentionally produced discharges.
Comment: 15 pages, 9 included postscript figures, 5 separate jpeg figures, submitted to Nucl. Instr. and Meth. A. A complete postscript version with high resolution figures 1, 3, 11, 12 and 14 can be found at http://www.nikhef.nl/~i06/RandD/final/letter4.ps
The GridPix detector is an assembly of a TimePix pixel chip, covered with a layer of silicon rich silicon nitride (SiRN) as protection against discharges, an integrated MPGD grid (InGrid), a drift gap and a cathode plane. GridPix detectors have been tested using a test beam at DESY. Measurements have been performed on single electron efficiency, time walk and robustness against discharges. Gossip is a GridPix detector with a drift gap of ~1mm. The concept is to replace the silicon in vertex detectors by ~1mm of gas. Gossip has been tested in a test beam at CERN and preliminary results are in agreement with simulations. DICE is a GridPix detector with a drift gap of ~2cm and is used for nuclear research at the TU Delft. DICE also has been used as reference detector for testing Gossip detectors in a test beam.
A GridPix detector is a gaseous detector capable of detecting single primary electrons from ionising particles. Such a detector consists of a pixel chip as active anode covered with a thin layer of silicon rich silicon nitride (SiRN) for protection against discharges. A layer of 8 JlIl1 SiRN, and according recent tests even 4 JlIl1, is sufficient to protect against discharges. The effect of the thickness of the SiRN layer on the operation of a detector has been determined. Time walk effects due to pixel electronics response time and gas gain statistics cause errors in drift time measurements thereby worsening the resolution in the drift direction. Simulations and measurements have been performed to determine how much time walk can be compensated for. GridPix detectors are high resolution low mass detectors that measures track segments ...
Marfan syndrome (MFS) is a connective tissue disorder with major features in cardiovascular, ocular and skeletal systems. Recently, diagnostic criteria were revised where more weight was given to the aortic root dilatation. We applied the revised Marfan nosology in an established adult Marfan population to define practical repercussions of novel criteria for clinical practice and individual patients. Out of 180 MFS patients, in 91% (n = 164) the diagnosis of MFS remained. Out of 16 patients with rejected diagnosis, four patients were diagnosed as MASS (myopia, mitral valve prolapse, borderline non-progressive aortic root dilatation, skeletal findings and striae) phenotype, three as ectopia lentis syndrome and in nine patients no alternative diagnosis was established. In 13 patients, the diagnosis was rejected because the Z-score of the...
In this work we have investigated the functioning of high resistivity amorphous silicon and silicon-rich nitride layers as a protection against discharges in Micro-Patterned Gaseous Detectors (MPGDs). When the anode is protected by a high resistivity layer, discharge signals are limited in charge. A signal reduction is expected when the layers are too thick; simulations presented in this paper indicate that layers up to 10 μm thick can be applied without significantly degrading the detector performance. Layers of amorphous silicon and silicon-rich nitride have been deposited on top of Timepix and Medipix2 chips in GridPix detectors; with this, chips survive naturally occurring as well as intentionally produced discharges. © 2010 Elsevier B.V. All rights reserved.
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