Speaker
Description
The dual radiator Ring Imaging Cherenkov (dRICH) detector is part of the particle identification system in the forward (ion-side) end-cap of the ePIC detector and complements the forward time-of-flight system and calorimetry.
The dRICH is required to provide continuous hadron identification from ~3 GeV/c to ~50 GeV/c, and to supplement electron and positron identification from a few hundred MeV/c up to about 15 GeV/c. Such an extended momentum range imposes the use of two radiators, gas and aerogel, with a common imaging system to ensure compactness and cost-effectiveness. The selected reference gas radiator is hexafluoroethane (C2F6), which matches the requirements being characterized by refractive index n = 1.00086 at STP and excellent chromatic dispersion. The aerogel radiator is a amorphous solid network of SiO2 nanocrystals whose density is tuned to get a refractive index of n = 1.026 at 400 nm wavelenght.
The dRICH has to provide open acceptance in the ePIC forward pseudo-rapidity range 1.5 - 3.5. To achieve proper light focalization within the due volume, the dRICH active area is curved and located behind the shadow of the barrel detector support, close to the ePIC solenoid coils. In this region, the ~1T strong and not-uniform ePIC magnetic field imposes the use of unprecedented detectors (SiPM). The dRICH is a ring-shaped detector, with a length of 1.27 m and a diameter of 3.6 m. In order to minimize the material budget, both the structure and the mirrors are made of composite materials.
During the R&D phase, the dual radiator principle and the single component performance have been validated. In this presentation, the status of the project will be presented. The design and technological choices will be discussed together with the results obtained by laboratory characterization of the component demonstrators and beam tests of the evolving prototypes.
