Encontrados 42 documentos, a visualizar página 1 de 5
Characterization of an energy dispersive X-ray fluorescence imaging system base...
Silva, A. L. M.; Azevedo, C. D. R.; Oliveira, C. A. B.; Santos, J. M. F. dos; Carvalho, M. L.; Veloso, J. F. C. A.An Energy Dispersive X-ray Fluorescence (EDXRF) imaging system based on a Micropattern Gas Detector has already shown good results for di erent applications. An X-ray tube, a pinhole camera and a Micro-Hole and Strip Plate (MHSP) based detector are the main components of the experimental system. The detector uses an MHSP in a Xe atmosphere at 1 bar, acting as a photon counting device, i.e., it is capable to rec...
Comparative studies of MSGC and GEM for photon and electron detection at ambien...
Mir, J. A.; Conceição, A. S.; Maia, J. M.; Veloso, J. F. C. A.; Santos, J. M. F. doshttp://www.sciencedirect.com/science/article/B6TJM-4TN0KR6-4/2/96e0a99e3367107c66c9d9bbccd7e9db
Efficient ion blocking in gaseous detectors and its application to gas-avalanch...
Lyashenko, A.; Breskin, A.; Chechik, R.; Santos, J. M. F. dos; Amaro, F. D.; Veloso, J. F. C. A.http://www.sciencedirect.com/science/article/B6TJM-4T8HH99-2/2/f970f5561a88e355e57ce6de077a59fa
The Photon-Assisted Cascaded Electron Multiplier Operation in CF _4 for Ion Ba...
Amaro, F. D.; Veloso, J. F. C. A.; Santos, J. M. F. dos; Breskin, A.; Chechik, R.; Lyashenko, A.The operation of the recently introduced photon assisted cascaded electron multiplier (PACEM) in CF4 is investigated. The PACEM uses the VUV scintillation produced in the electron avalanches of the first multiplier of the cascade to transfer the signal to the subsequent ones. The VUV scintillation induces the emission of a large number of photoelectrons from a Csl photocathode placed on the top-surface of the s...
PACEM: a new concept for high avalanche-ion blocking
Veloso, J. F. C. A.; Amaro, F. D.; Azevedo, C. D. R.; Santos, J. M. F. dos; Breskin, A.; Lyashenko, A.; Chechik, R.We present the Photon-Assisted Cascaded Electron Multiplier (PACEM) as a potential alternative for ion back-flow suppression in gaseous cascade electron multipliers. Using a Micro Hole and Strip Plate-Gas Electron Multiplier (MHSP-GEM) configuration, the number of ions flowing back to the scintillation region is about 1.5 ions per primary electron at an optical gain of 6.5 and a drift field of 0.1 kV/cm, and ab...
Further studies on the gain properties of a Gas Electron Multiplier with a Micr...
Mir, J. A.; Stephenson, R.; Rhodes, N. J.; Schooneveld, E. M.; Luz, H. Natal da; Veloso, J. F. C. A.; Santos, J. M. F. dos; Azevedo, C. D. R.A Gas Electron Multiplier with Micro-Induction Gap Amplifying Structure (GEM-MIGAS) is formed when the induction gap of the GEM is set between 50 and 100 [mu]m using kapton pillars spaced at regular intervals. This configuration combines the properties of a GEM and Micromegas, allowing operation in tandem to generate high charge gains. We measured the essential operational parameters of this system using argon-...
A simple X-ray position detection system based on a MHSP
Luz, H. Natal da; Veloso, J. F. C. A.; Santos, J. M. F. dos; Mir, J. A.A simple system for position detection based on a Micro-Hole and Strip Plate (MHSP) using a resistive charge division method was implemented. A thin resistive layer of about 100 [Omega] between each strip (top surface) and between each anode strip (bottom surface) allows us to obtain the actual position in both orthogonal directions. The readout electronics uses only two preamplifiers, a sum and a divider circu...
Micro-hole and strip plate-based photosensor
Freitas, E. D. C.; Veloso, J. F. C. A.; Breskin, A.; Chechik, R.; Amaro, F. D.; Ferreira, L. F. Requicha; Maia, J. M.; Santos, J. M. F. dosThe performance of a new VUV photosensor, based on an micro-hole and strip plate (MHSP) electron multiplier with a CsI photocathode deposited on its top electrode, is described. This photosensor presents gains above 104 when operating in an Ar-5%Xe gas mixture at 1 atm. Although the gain of a single MHSP is not sufficient for efficient detection of single photons, this simple UV photosensor may be useful for th...
Micro-Hole and Strip Plate (MHSP) operation in CF4
Luz, H. Natal da; Mir, J. A.; Veloso, J. F. C. A.; Santos, J. M. F. dos; Rhodes, N. J.; Schooneveld, E. M.The Micro-Hole and Strip Plate (MHSP) is a hybrid electron multiplier which combines the working principles of a Gas Electron Multiplier (GEM) and a Micro-Strip Gas Counter (MSGC). The compact double stage electron multiplication processes found in the MHSP enables the realisation of higher gas gain than the lone GEM operation. Thermal neutron detection using gas detectors involves the use of gas with another s...
High-rate operation of the Micro-Hole and Strip Plate gas detector
Veloso, J. F. C. A.; Caldas, C. C.; Oliveira, C. A. B.; Azevedo, C. D. R.; Santos, J. M. F. dos; Breskin, A.; Chechik, R.We report the performance of the Micro-Hole-and-Strip-Plate (MHSP) operated in xenon, under high-flux irradiation of a 30-kV X-ray Cu-tube. Stable operation in pulse-counting mode for gas gains above 104 was measured up to counting rates of 5×105 Hz/mm2. A gain variation of less than 5% was observed for gains of 104, while the energy resolution for 8-keV X-rays degrades from ~16% to ~18%. No visible degradation...
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