22 documents found, page 1 of 3

Contributo para a identificação dos processos responsáveis pela composição das ...

Hydrogeochemical study of thermo-mineral waters in Lisbon region (Portugal) : c...

Contributo para a identificação dos processos responsáveis pela composição das ...

Neutron capture cross section measurements for nuclear astrophysics at CERN n_TOF

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...

Performance of shielded timing RPCs in a 12C fragmentation experiment

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 large area timing RPC prototype for ion collisions in the HADES spectrometer

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

An RPC-PET prototype with high spatial resolution

A small positron emission tomography system, based on the timing RPC technology has been built and tested. This first prototype is aimed at validating the expectations, derived from simulations, of a very high spatial resolution, which could be of value for the imaging of small animals. The system is composed of two counting heads, able to measure the photon interaction point in two dimensions, the transaxial d...

Measurement of the n_TOF beam profile with a micromegas detector

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 ...

Progress in timing Resistive Plate Chambers

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.sciencedir...

A study of ageing in timing RPCs

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...