Speaker
M. Sabaté-Gilarte
(CEA/CERN/Universidad de Sevilla)
Description
The neutron time-of-flight (n_TOF) is a neutron beam facility at the European Organization for Nuclear Research (CERN), mainly dedicated to measure neutron-induced cross sections for nuclear technology, astrophysics and basic nuclear physics applying the time of flight technique. A proton beam with momentum of 20 GeV/c is produced in the PS at CERN and impinging on a cylindrical lead target. By spallation processes a large number of neutrons are generated. Neutrons fly 185 m in a horizontal direction through an evacuated beam tube until they reach the first experimental area, EAR1, as well as 20 m in the vertical direction, 90 º, to reach EAR2.
MicroMegas detector systems are used at n_TOF for monitoring purposes, i.e., to characterize the neutron flux of the facility. In particular the energy dependence of the neutron flux is important for cross section measurements. The absolute level of flux is determined by a reference cross section. While for fission or charge particles neutron induced reaction, a ratio cross section is obtained respect to a standard reference. For the new EAR2 the expected count rate is 100 times higher as compared with EAR1. Therefore, a new design based on microbulk technology was developed to minimize in-beam material that contributes to the background. The Anode electrode was segmented in four pads to reduce the capacitance of the detector and the count rate with respect to the MESH electrode.
