Demonstrator system for the high-luminosity upgrade of the ATLAS hadronic Tile Calorimeter electronics

The ATLAS Tile Calorimeter (TileCal) is a hadronic sampling calorimeter made of steel tiles as absorber and plastic scintillating tiles as active medium. The scintillating tiles are read out by wavelength shifting fibers to photomultiplier tubes (PMTs). The analog PMT signals are shaped, conditioned, and then digitized every 25 ns before being sent off-detector. The high-luminosity upgrade to the LHC (HL-LHC) presents significant challenges for ATLAS and TileCal, including greater radiation exposure to the on-detector electronics and increased pileup from low momentum collisions affecting trigger selection performance. A full replacement of the on- and off-detector electronics for TileCal will take place in preparation for the HL-LHC program. in 2026. The new system is designed to digitize and transmit all sampled calorimeter data to the off-detector systems, where the data are stored in latency pipelines while quasi-projective digital trigger tower sums are formed and forwarded to the level-1 trigger. The design of the Phase-II system has included a long R&D program and extensive test beam studies. The design includes state of the art electronics with extensive use of redundancy and radiation tolerant electronic components to avoid single points of failure. Multi-Gbps optic links drive the high volume of data transmission and Field Programmable Gate Arrays (FPGAs) provide digital functionality both on- and off detector. A hybrid demonstrator prototype module, instrumented with new module electronics as well as interfaces for backward compatibility with the present system was assembled and inserted in ATLAS in June 2019 in order to gain experience in actual detector conditions. We present the current status and test results from the Phase-II upgrade demonstrator module running in ATLAS.