Shift of the Cs hyperfine transition frequency due to thermal radiation: experimental verification

Summary form only given, as follows.It was observed that thermal radiation emitted from a black surface surrounding the atomic beam of a caesium atomic clock leads to a decrease of the clock transition frequency when the black surface is heated to about 470 K. The magnitude of the observed effect is in agreement with previous theoretical predictions at the level of the present stage of the evaluation of the experimental data.