Analysis of different fused silica fibers irradiated in the LHC TAN during the 2023 Heavy Ion Run*

The Target Absorbers for Neutrals (TAN) in the CERN Large Hadron Collider (LHC) is one of the most irradiated regions in the accelerator during the data taking. The near future High Luminosity (HL) upgrade of the machine is expected to drastically increase the radiation challenges for detectors installed in the tunnel, including the ATLAS Reaction Plane Detector (RPD). The RPD uses fused silica fibers as both active Cherenkov radiator core and readout channel. Characterization of the performance of these fibers under radiation with conditions similar to those experienced during the LHC run is a must for the development of new RPD detectors for the HL-LHC era.

Our group is collaborating with the CERN FLUKA team to irradiate different fused silica fibers in situ at the LHC to identify the best candidate for the construction of the new RPD. A variety of fused silica-based fibers were installed in the LHC TAN behind the ATLAS RPD and irradiated during the 2023 Heavy Ion Run. After extraction, they were sent to the University of Illinois at Urbana-Champaign for analysis of their optical properties. In this contribution, I will present the status of the analysis of these fibers and outline what the next steps are towards the finalization of the R&D studies for the new generation of HL RPDs.