  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 on beam before and after irradiation both at CERN-SPS and
at DESY, and their performances 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 $\Phi \lesssim 7\times10^{15}\rm{n_{eq}/cm^2}$ and
module power consumption is within the specified limits. Moreover, at a fluence
$\Phi = 1.3\times10^{16}\rm{n_{eq}/cm^2}$, hit-efficiency is still as high as
88\% and charge collection efficiency is about 30\%.
