GIF$++$: The new CERN Irradiation Facility to test large-area detectors for HL-LHC

The high-luminosity LHC (HL-LHC) upgrade is setting a new challenge for particle detector technologies. The increase in luminosity will produce a higher particle background with respect to present conditions. In order to study performance and stability of detectors at LHC and future HL-LHC upgrades, a new dedicated facility has been built at CERN: the Gamma Irradiation Facility (GIF++). The GIF++ is a unique place where high energy charged particle beams (mainly muons) are combined with gammas from a 14 TBq 137Cesium source which simulates the background expected at the LHC experiments. Several centralized services and infrastructures are made available to all the LHC detector community for facilitating the different R&D programs.