Towards black body radiation shift uncertainty in optical lattice clocks at 10 −18 level at room temperatures

We present current status of work on blackbody radiation impact on ultra-narrow optical resonances. The emissivities of the most popular materials, which are used for construction of vacuum chambers, have been measured in the temperatures close to the room temperature. We have developed a new vacuum system designed exclusively for the emissivity measurements. We have measured the emissivity of samples made from different materials and with different finishing. This data has been also used to perform numerical simulation of temperature distribution of an optical clock vacuum set-up.