Encontrados 11 documentos, a visualizar página 1 de 2
A low-mass neutron flux monitor for the n _TOF facility at CERN
Mastinu,P. F.; Abbondanno,U.; Aerts,G.; Alvarez,H.; Andriamonje,S.; Angelopoulos,A.; Assimakopoulos,P.; Bacri,C.O.; Badurek,G.; Baumann,P.; Becvár,F.A small-mass system has been developed for monitoring the flux of neutrons with energy up to 1 MeV at the new time-of-flight facility at CERN, n_TOF. The monitor is based on a thin Mylar foil with a 6Li deposit, placed in the neutron beam, and an array of Silicon detectors, placed outside the beam, for detecting the products of the 6Li(n, alpha)³H reaction. The small amount of material on the beam ensures a min...
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...
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...
Measurement of the n_TOF beam profile with a micromegas detector
Pancin, J.; Abbondanno, U.; Aerts, G.; Alvarez, H.; Andriamonje, S.; Angelopoulos, A.; Assimakopoulos, P.; Bacri, C.; Badurek, G.; Baumann, P.A Micromegas detector was used in the neutron Time-Of-Flight (n_TOF) facility at CERN to evaluate the spatial distribution of the neutron beam as a function of its kinetic energy. This was achieved over a large range of neutron energies by using two complementary processes: at low energy by capture of a neutron via the 6Li(n,[alpha])t reaction, and at high energy by elastic scattering of neutrons on gas nuclei ...
Perspectives for positron emission tomography with RPCs
Blanco, A.; Chepel, V.; Ferreira-Marques, R.; Fonte, P.; Lopes, M. I.; Peskov, V.; Policarpo, A.In this study, we address the feasibility and main properties of a positron emission tomograph (PET) based on RPCs. The concept, making use of the converter-plate principle, takes advantage of the intrinsic layered structure of RPCs and its simple and economic construction. The extremely good time and position resolutions of RPCs also allow the TOF-PET imaging technique to be considered. ; http://www.science...
High-resolution TOF with RPCs
Fonte, P.; Peskov, V.In this work, we describe some recent results concerning the application of Resistive Plate Chambers operated in avalanche mode at atmospheric pressure for high-resolution time-of-flight measurements. A combination of multiple, mechanically accurate, thin gas gaps and state-of-the-art electronics yielded an overall (detector plus electronics) timing accuracy better than 50 ps [sigma] with a detection efficiency...
Breakdown limit studies in high-rate gaseous detectors
Ivaniouchenkov, Yu.; Fonte, P.; Peskov, V.; Ramsey, B. D.We report results from a systematic study of breakdown limits for novel high-rate gaseous detectors: MICROMEGAS, CAT and GEM, together with more conventional devices such as thin-gap parallel-mesh chambers and high-rate wire chambers. It was found that for all these detectors, the maximum achievable gain, before breakdown appears, drops dramatically with incident flux, and is sometimes inversely proportional to...
Single-electron pulse-height spectra in thin-gap parallel-plate chambers
Fonte, P.; Ferreira-Marques, Rui; Peskov, V.; Policarpo, A.Single-electron pulse-height spectra were measured in 0.6 and 1.2 mm parallel-plate chambers developed for the TOF system of the ALICE/LHC-HI experiment. Mixtures of Ar with ethane, isobutane, and SF6 were studied. The observed spectrum shows a clear peak for all gases, suggesting efficient single-electron detection in thin parallel-plate structures. The pulse-height spectrum can be described by the weighted su...
A spark-protected high-rate detector
Fonte, P.; Carolino, N.; Costa, L.; Ferreira-Marques, Rui; Mendiratta, S.; Peskov, V.; Policarpo, A.We developed a very low resistivity RPC-type detector, the anode of which was a plate made from materials with resistivity up to 5×107 [Omega] cm, the cathode being a metallic mesh preceded by a drift region. ; http://www.sciencedirect.com/science/article/B6TJM-3WX21P9-J/1/b56046b528d4eca75db4fdb2995304b5
Rate and gain limitations of MSGCs and MGCs combined with GEM and other preampl...
Fonte, P.; Peskov, V.; Ramsey, B. D.We have studied the rate and gain limits of diamond-coated Microstrip Gas Counters (MSGCs) and Micro-Gap Counters (MGCs) when combined with various preamplification structures: Gas Electron Multiplier (GEM), Parallel-Plate Avalanche Chamber (PPAC) or a MICROMEGAS-type structure. Measurements were done both with X-rays and alpha particles with various detector geometries and in different gas mixtures at pressure...
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