Piccolo Micromegas: First in-core measurements in a nuclear reactor

An Accelerator Driven System (ADS) consists in the coupling of an accelerator with a nuclear reactor. Such systems will need neutron detectors working in a wide energy range and insensitive to X- and γ -rays. Micromegas technology has been proposed to achieve this goal. The ability of Micromegas to detect neutrons over a wide energy range has already been demonstrated and this detector is, under certain conditions, insensitive to γ -rays. A new Micromegas neutron detector called Piccolo Micromegas has been designed to get integrated neutron fluxes on different energy domains. For the first time, Piccolo Micromegas has been placed in the core of a nuclear reactor at Casaccia in Italy. The configuration of the detector will be presented as well as its functioning and the reasons of its insensitivity to γ -rays. The results of the operation of the detector will also be shown for low reactor power to high reactor power and some improvements will be suggested.