Encontrados 17 documentos, a visualizar página 1 de 2
Status and outlook of the neutron time-of-flight facility n_TOF at CERN
Gunsing, F.; Abbondanno, U.; Aerts, G.; Alvarez, H.; Álvarez-Velarde, F.; Andriamonje, S.; Andrzejewski, J.; Assimakopoulos, P.; Audouin, L.The neutron time-of-flight facility n_TOF at CERN, fully operational since 2002, combines a high instantaneous neutron flux with high energy resolution. The wide energy range and the high neutron flux per time-of-flight burst result in a much enhanced signal to background ratio for neutron capture of radioactive isotopes and makes this facility well suited for the measurement of high quality neutron-induced rea...
Neutron reactions and nuclear cosmo-chronology
Mosconi, M.; Heil, M.; Käppeler, F.; Mengoni, A.; Plag, R.; Fujii, K.; Gallino, R.; Aerts, G.; Terlizzi, R.; Abbondanno, U.; Álvarez-Pol, H.The [beta]-decay of 187Re represents a suited cosmo-chronometer for the age of the r-process abundances, since the radiogenic part of the daughter isotope 187Os is defined by the difference between the solar 187Os abundance and s-process contribution to 187Os. The latter component can be determined via the s-process systematics based on the stellar neutron capture cross sections of 186Os and 187Os. The laborato...
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...
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 ...
Neutron capture cross section measurements for nuclear astrophysics at CERN n_TOF
Abbondanno, U.; Aerts, G.; Alvarez-Velarde, F.; Álvarez-Pol, H.; Andriamonje, S.; Andrzejewski, J.; Badurek, G.; Baumann, P.; Becvár, F.; Benlliure, J.A series of neutron capture cross section measurements of interest to nuclear astrophysics have been recently performed at n_TOF, the neutron spallation source operating at CERN. The low repetition frequency of the proton beam driver, the extremely high instantaneous neutron flux, and the low background conditions in the experimental area are optimal for capture cross section measurements on low-mass or radioac...
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...
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
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...
A study of ageing in timing RPCs
Lopes, L.; Ferreira-Marques, R.; Fonte, P.; Piedade, A. P.; Policarpo, A.The present study concerns the search for ageing effects in 0.3 mm gap timing RPCs. Counters were made with glass and aluminium electrodes and kept under a continuous gas flow of tetrafluorethane with 10% sulphur hexafluoride, 5% isobutane and water at 10% relative humidity. After 500 days of operation at the saturation current an accumulated charge of 800 mC was collected, equivalent to over 8 years of continu...
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