Cold SR atoms for an optical frequency standard

Sr-atoms are of special interest for an optical frequency standard since a large number of atoms can be cooled down efficiently to ultra-low temperatures in a magneto-optical trap (MOT). The ultra-narrow line on the forbidden ¹S₀ -> ³P₀ transition of ⁸⁷Sr (³P₀ natural lifetime is approx. 100 s), and the ability to interrogate Sr atoms in a perturbation free dipole trap promise un-precedented low inaccuracy level and relative frequency instability, well below 10^-15 tau^-1/2 . We will show the realization of an efficient atomic source of cold Sr atoms and the construction of an ultra-stable laser for the interrogation of the atoms.