High rate capability and radiation tolerance of the new CMS pixel detector readout chip PROC600

The first layer of the CMS Phase~1 pixel detector will be located at a distance of 3 cm from the interaction point. Pixel hit rates up to 600 MHz/cm$^2$ are expected at the instantaneous luminosity of $2 \times 10^{34}cm^{-2}s^{-1}$ foreseen by LHC in the coming years. The CMS Phase~1 pixel detector will be in operation until 2024/25 and the total fluence received by the first layer in its lifetime will reach $2-3\times 10^{15}n_{eq} / cm^2$ that corresponds to 0.8-1.2 MGy. A new readout chip, called PROC600, to be used for layer~1 modules has been designed at PSI. To validate robust and efficient operation of PROC600, it has been irradiated to doses ranging from 0.6 MGy up to 4.8 MGy. The chip performance before and after irradiation including the pixel hit efficiency will be presented.