Optical Transmission Measurements of Fused Silica Materials Irradiated to MGy Scale at the CERN Large Hadron Collider*

The High-Luminosity (HL) upgrade of the CERN LHC will significantly increase its collision rate, giving rise to an extremely high-radiation environment that results in significant challenges for forward detectors, such as the Zero Degree Calorimeters (ZDCs) of the ATLAS and CMS experiments. Because they share the same radiation environment and technological challenges, the ATLAS and CMS ZDC groups formed the Joint Zero degree Calorimeter Project (JZCaP) to design and construct the new generation of ZDCs for the HL-LHC.  The Nuclear Physics Lab at the University of Illinois leads the JZCaP effort.

JZCaP is collaborating with the CERN BRAN and FLUKA teams to irradiate fused silica samples in situ at the LHC,  to identify radiation-hard fused silica materials that can be used as Cherenkov radiators in the HL-ZDC and HL-BRAN detectors.

LHC Run 3 provides a unique opportunity to test further the radiation hardness of fused-silica materials reaching unprecedented radiation levels. A variety of fused silica-based fibers and rods were installed in the LHC TAN, where the ZDC and the BRAN are located, to irradiate the materials and study their optical properties after Run 3 ends. In this talk, I will present the results of Run 2 irradiation studies and plans for Run 3 irradiation campaign.