A large area Resistive Plate Chamber (RPC) with a total active surface of 160 Â 10 cm 2 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. A timing resolution between 50 and 75 ps s with an efficiency for Minimum Ionizing Particles (MIPs) larger than 95% was attained over the whole active area, in addition with a position resolution along the strips of 1.2 cm. Despite the large active area per electronic channel, the observed timing resolution is remarkably close to the one previously obtained (50 ps s) with much smaller chambers of about 10 cm 2 area. These results open perspectives of extending the application of timing RPCs to large area arrays exposed to moderate particle multiplicities, where the low cost, good time resolution, insensitivity to the magnetic field and compact mechanics may be attractive when compared with the standard scintillator-based Time-of-Flight (TOF) technology.
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 s 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 technology with significantly lower price per channel and being compatible with magnetic fields.In this work, we report recent developments of the timing RPC technology, including a large area counter (0.16 m 2 ) and smaller, position-sensitive, single-gap counters. The latter devices are aimed to be applied in small and accurate TOF systems using a multilayer structure.The large counter has shown a timing resolution between 50 and 75 ps s over the whole active area, with 96% efficiency and very small timing tails, along with a longitudinal position-resolution of 1.2 cm s: The single-gap counters had a timing resolution of 55 ps s and a bi-dimensional position-resolution better than 3 mm FWHM. It was calculated that a 4-layer configuration of such counters would yield a time resolution of 33 ps s essentially free from timing tails. r
En teoría del valor y en teoría normativa, es común considerar que lo positivo y lo negativo tienen la misma importancia. Algunas rechazan esta idea y consideran que lo negativo tiene mayor importancia. Aquí se presentarán algunos de los argumentos en favor de la asimetría. Tras esto, daré cuenta de los diferentes tipos de posiciones asimétricas defendibles. Explicaré cuáles son las características de cada teoría y qué puntos a favor y en contra de estas posiciones se pueden postular. Por último, consideraré que no hay razones para creer que haya una posición asimétrica claramente superior a las demás.
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