Neutron detection in high γγ background using a micromegas detector

The ability of Micromegas to detect neutrons over a wide energy range has already been demonstrated. However, in some nuclear experiments or applications, neutrons come with high photon flux disturbing the detectors. A new project for nuclear waste characterization using photonuclear reactions is under development at the CEA. One of the ideas is to detect the prompt neutrons produced by these kinds of reactions, which are accompanied by a strong γγ flash. The micromegas detector has been chosen to detect these neutrons since it is quite insensitive to γγ-rays under certain conditions. The configuration of this detector will be presented and its γγ insensitivity demonstrated. Results from simulations and experiments will be shown.