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Progress in timing Resistive Plate Chambers
Blanco, A.; Carolino, N.; Correia, C. M. B. A.; Ferreira-Marques, R.; Fonte, P.; Gobbi, A.; González-Díaz, D.; Lopes, M. I.; Lopes, L.; Macedo, M. P.Timing RPCs are Resistive Plate Chambers made with glass and metal electrodes separated by precision spacers. Typical gas gaps are a few hundred micrometers wide. Such counters were introduced in 1999 and have since reached timing accuracies below 50 ps [sigma] with efficiencies above 99% for MIPs. Applications in high-energy physics have already taken place with several more under study. ; http://www.scienc...
Single-gap timing RPCs with bidimensional position-sensitive readout for very a...
Blanco, A.; Ferreira-Marques, R.; Finck, Ch.; Fonte, P.; Gobbi, A.; Policarpo, A.In this work, we report the development and performance of single-gap timing RPCs equipped with a 3 mm FWHM resolution bidimensional position-sensitive readout and reaching a timing resolution of 55 ps [sigma] at an efficiency of 75% for MIPs. These chambers are aimed to be applied in a multilayer geometry, forming small and very accurate TOF systems. The avalanche localization capability would provide informat...
Many particle theory for the luminescence, characterization and simulation of q...
Pereira Jr.,M.F.; Bernussi,A. A.; Carvalho Jr.,W.; Furtado,Mario T.; Gobbi,A. L.A photon Green's function theory is used to incorporate Bethe- Salpeter-like many body corrections in the the computations of nonlinear optical spectra of semiconductor quantum well laser materials. The numerical results presented reproduce several features found in the experimental characterization of the actual devices.
A large area timing RPC
Blanco, A.; Ferreira-Marques, R.; Finck, Ch.; Fonte, P.; Gobbi, A.; Policarpo, A.; Rozas, M.A large area Resistive Plate Chamber (RPC) with a total active surface of 160×10 cm2 was built and tested. The surface was segmented in two 5 cm wide strips readout on both ends with custom, very high frequency, front-end electronics. ; http://www.sciencedirect.com/science/article/B6TJM-44JHY5B-8/1/909cdae0fda12f2c09d271fc07f60f5b
Development of large area and of position-sensitive timing RPCs
Blanco, A.; Marques, R. Ferreira; Finck, Ch.; Fonte, P.; Gobbi, A.; Mendiratta, S. K.; Monteiro, J.; Policarpo, A.; Rozas, M.Resistive Plate Chambers (RPC) made with glass and metal electrodes forming accurately spaced gas gaps of a few hundred micrometers have reached timing accuracies below 50 ps [sigma] with efficiencies above 99% for MIPs. This type of detector, operating at atmospheric pressure with non-flammable gases, seems well suited for large TOF systems, providing performances comparable to the scintillator-based TOF techn...
Caracterização ultra-sônica de materiais ferroelétricos com estrutura perovskit...
Moreno-Gobbi,A.; Paolini,G.; Pérez,M.; Negreira,C. A.; Garcia,D.; Eiras,J. A.Atenuação e velocidade ultra-sônicas e, consequentemente, o módulo de Young de cerâmicas ferroelétricas com estrutura do tipo perovskita e tungstênio-bronze foram medidas entre 2,5 e 30 MHz, à temperatura ambiente, utilizando-se a técnica de pulso-eco. Composições com e sem chumbo foram testadas, mostrando que a presença do cátion Pb2+ representa fator importante no comportamento da atenuação. A dependência da ...
Size effects on the growth mode and roughness of sub-micron structures grown by...
Gutiérrez,H.R.; Cotta,M.A.; Nakaema,W.M.; Carvalho,M.M.G.de; Gobbi,A.L.We have observed changes in the morphology of InP films grown in epi-ready substrates and on patterns created by photo and plow-mode AFM lithography. These changes are attributed to different levels of contamination of the surface, which favor nucleation of clusters over a two-dimensional film for the lithography-processed surface. The area of nucleation is smaller than the dimensions of the patterns created by...
Strain and relaxation processes in In1-xGa xAs yP1-y/ InP single quantum wells ...
Bernussi,A.A.; Carvalho Jr.,W.; Furtado,M.T.; Gobbi,A.L.Strained and partially relaxed In1-xGa xAs yP1-y /InP single quantum wells (SQWs) with different cap layer thicknesses and biaxial strain values grown by low-pressure metalorganic vapor phase epitaxy (LP-MOVPE) were investigated by double crystal X-ray diffraction, photoluminescence microscopy (PLM) imaging and photoluminescence spectroscopy techniques. Our results indicate a significant improvement of the opti...
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