Test beam results of irradiated modules for the CMS Phase-2 upgrade equipped with HPK planar pixel sensors and RD53B-CMS readout chips

The upcoming High-Luminosity running phase of the LHC will require a complete replacement of the current tracking system in the CMS experiment. With the planned integrated luminosity of up to 4000 fb−1 to be delivered to the experiments, the innermost layers of the CMS Inner Tracker (IT) will face particle fluences of up to a non-ionizing energy loss (NIEL) of Φeq = 3.5 × 1016 cm−2. Through an extensive R&D program involving multiple vendors, several pixel sensor options have been thoroughly evaluated, considering different pixel pitches and sensor cell designs. Recently, the final choices have been made. All layers, except the innermost layer of the barrel section of the IT, will be equipped with planar n-in-p sensors featuring an active thickness of 150μm and pixel pitches of 25 × 100μm2. During the initial phase of the sensor qualification campaign, the sensors were coupled with demonstrator chips (RD53A), and the modules were exposed to fluences of up to Φeq = 2.0 × 1016 cm−2, undergoing comprehensive testing at both CERN and DESY test beam facilities. In 2023, single chip assemblies, along with the first full modules incorporating the final, full-size prototype readout chip (RD53B-CMS) irradiated up to Φeq = 1.0 × 1016 cm−2, have become available and were tested at DESY. In this article, an overview of the preliminary test beam results will be provided. The studies will cover hit efficiency, spatial resolution, and noise hit occupancy for both non-irradiated samples and irradiated assemblies. The preliminary findings are in line with previous results obtained with RD53A assemblies. The measurements described in this contribution paved the way for the submission of the final readout chip and kickoff batches for planar production sensors for the Inner Tracker that have been launched recently.