The new CLAS12 spectrometer that will be installed in the Hall B is made of a forward detector for measuring the higher energy particles produced in the hard scattering of quarks inside the nucleon target and of a central detector for recoil particle measurements. The forward detector is based on a toroidal field and is divided in 6 azimuthal sectors. In its present configuration, it allows good identification of pions and nucleons. However, it is not able to correctly identify kaons in the range of momenta between 3 and 8 GeV/c. For this reason, the realization of a Ring Imaging CHerenkov (RICH) detector has been proposed by the INFN physicists. Such detector is basically composed of a radiator where the particles produce a cone of Cherenkov light, a gap where the photons propagate and an array of photodetectors. Since the opening angle of the cone depends on the speed of the particle, measuring the radius of the ring allows the identification of the particle itself. The constraints imposed by the geometry of CLAS12 forced to choose a hybrid configuration, in which part of the photons are directly detected, while part of them are detected only after a double reflection on a mirror system. Thus, depending on the number of reflections, the pattern of the photons measured by the photodetectors may show full circles as well as pieces of circles. The construction of one RICH sector is currently underway.
It uses a layer of aerogel of several squared meters and different thickness as radiator material, about 400 Multi-