Fast Ionization Chamber and MicroMegas detector from the n_TOF experiment

An ionization chamber with fast timing properties was built at CERN for measuring fission cross-sections of minor actinides at the n_TOF neutron beam. The design of this chamber and of the front-end electronics was optimized to match the innovative features of the n_TOF facility, in particular the high instantaneous neutron flux and low background. Micromegas (Micro-MEsh Gaseous Structure) detectors are gas detectors consisting of a stack of one ionization and one proportional chamber. A micromesh separates the two communicating regions, where two different electric fields establish respectively a charge drift and a charge multiplication regime. The n_TOF facility at CERN provides a white neutron beam (from thermal up to GeV neutrons) for neutron induced cross section measurements.