Performance of thin planar n-on-p silicon pixels after HL-LHC radiation fluences

The tracking detector of ATLAS, one of the experiments at the Large Hadron Collider (LHC), will be upgraded in 2024–2026 to cope with the challenging environment conditions of the High Luminosity LHC (HL-LHC). The LPNHE, in collaboration with FBK and INFN, has produced $130\mu m$ thick $n-on-p$ silicon pixel sensors which can withstand the expected large particle fluences at HL-LHC, while delivering data at high rate with excellent hit efficiency. Such sensors were tested in beam before and after irradiation both at CERN-SPS and at DESY, and their performance are presented in this paper. Beam test data indicate that these detectors are suited for all the layers where planar sensors are foreseen in the future ATLAS tracker: hit-efficiency is greater than 97% for fluences of $\Phi \lesssim 7\times 10^{15}{n}_{\text{eq}}∕{\text{cm}}^2$ and module power consumption is within the specified limits. Moreover, at a fluence of $\Phi =1.3\times 10^{16}{n}_{\mathrm{eq}}∕{\mathrm{cm}}^2$, hit-efficiency is still as high as 88% and charge collection efficiency is about 30%.