Encontrados 24 documentos, a visualizar página 1 de 3
Accurate timing of gamma rays with high-rate Resistive Plate Chambers
Lopes, L.; Pereira, A.; Fonte, P.; Marques, R. FerreiraThe counting rate capability of RPCs is strongly conditioned by the availability of suitable resistive materials for the electrodes. For time-of-flight measurements in heavy-ion high-energy physics, the extension of the counting rate capabilities achievable with glass electrodes, around 2 kHz/cm2, to much higher values is of fundamental importance. To address this issue we developed single-gap tRPCs with electr...
Very high position resolution gamma imaging with resistive plate chambers
Blanco, A.; Carolino, N.; Correia, C. M. B. A.; Fazendeiro, L.; Ferreira, Nuno C.; Marques, M. F. Ferreira; Marques, R. Ferreira; Fonte, P.; Gil, C.In this study we present experimental results from a first prototype of a positron emission tomography system based on the resistive plate chamber (RPC) technology. The system is composed of two counting heads, each one containing 16 single-gap RPC detectors capable of detecting the photon interaction point in the transaxial plane. Uniformity studies were performed for image resolution and sensitivity, yielding...
Ceramic high-rate timing RPCs
Lopes, L.; Marques, R. Ferreira; Fonte, P.; Hennetier, L.; Pereira, A.; Correia, A. M. SousaFollowing some previous work, we report here considerable improvements on the counting rate capability of timing RPCs by the use of ceramic electrodes with a resistivity of 109 [Omega][dot operator]cm. The X-ray sensitivity of the detector depends linearly on the counting rate with a slope of 9% per 100 kHz/cm2, free from charge depletion effects, while keeping a timing accuracy, measured with 511 keV synchrono...
An analytical description of rate effects in timing RPCs
González-Díaz, D.; Fonte, P.; Garzón, J. A.; Mangiarotti, A.An analytical framework for describing the RPC behavior under high irradiation is proposed, including the effect of the fluctuations of the field. The description is compared with an equivalent MC and data for timing RPCs, showing good agreement. Moreover, the formalism allows to clearly identify the main variables ruling the process. ; http://www.sciencedirect.com/science/article/B6TVD-4KV4MR8-W/1/788b06292...
Spatial resolution on a small animal RPC-PET prototype operating under magnetic...
Blanco, A.; Carolino, N.; Correia, C. M. B. A.; Fazendeiro, L.; Ferreira, Nuno C.; Marques, M. F. Ferreira; Marques, R. Ferreira; Fonte, P.; Gil, C.It has been demonstrated in previous work that the RPC-PET technology is able to deliver radioisotope image resolutions approaching the physical limits of the PET principle. Here we study, by simulation, the effect of the magnetic field on the positron range to evaluate whether the spatial resolution of the RPC-PET could be improved by using an intense magnetic field. Six positron emitters of interest to small ...
The effect of temperature on the rate capability of glass timing RPCs
González-Díaz, D.; Belver, D.; Blanco, A.; Marques, R. Ferreira; Fonte, P.; Garzón, J. A.; Lopes, L.; Mangiarotti, A.; Marín, J.In this study, we demonstrate a strong influence of the working temperature on the counting rate capability of large-area timing resistive plate chambers (RPCs) incorporating industrial flat glass electrodes. The effect relies on the sharp dependence of glass resistivity on temperature, approximately one order of magnitude for each 25 °C, allowing a considerable extension of the counting rate capability merely ...
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...
A large area timing RPC prototype for ion collisions in the HADES spectrometer
Alvarez Pol, H.; Alves, R.; Blanco, A.; Carolino, N.; Eschke, J.; Ferreira-Marques, R.; Fonte, P.; Garzón, J. A.; González Díaz, D.; Pereira, A.We present a resistive plate chamber (RPC) prototype for time-of-flight measurements over large areas and at high occupancies, minimizing the inter-channel cross-talk. ; http://www.sciencedirect.com/science/article/B6TJM-4D75GPD-9/1/a6fe40c114a867a0f98e2fec0f133503
Development of high-rate timing RPCs
Lopes, L.; Marques, R. Ferreira; Fonte, P.; Pereira, A.; Peskov, V.; Policarpo, A.For many applications of RPCs to time-of-flight counters in heavy ion experiments the expansion to much higher values of the counting rate capability, so far limited to around 2 kHz/cm2 is of fundamental importance. To address this issue we developed single-gap timing RPCs with resistive electrodes made from a commercially available plastic material. Tests performed in photon beams yielded a time resolution aro...
Performance of shielded timing RPCs in a 12C fragmentation experiment
Alvarez Pol, H.; Alves, R.; Blanco, A.; Carolino, N.; Eschke, J.; Ferreira-Marques, R.; Fonte, P.; Garzón, J. A.; González Díaz, D.; Pereira, A.We show the feasibility of large area timing RPC detectors for experiments dealing with fragmentation-like primary interactions and/or high detector multiplicities, without significative degradation of the detector capabilities. The tested prototype is constituted by three independent cells placed into grounded aluminium boxes, which reduce the cross-talk to the level of 0.4%. Each box consists of a 4-gap glass...
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