AN IMPROVED TEST OF RELATIVISTIC TIME DILATION WITH FAST, STORED IONS

A precise, laser-spectroscopic test of time dilation in special relativity has been performed with fast ions stored in the heavy-ion storage ring TSR in Heidelberg. At a velocity of 6.4% of the speed of light, the Doppler-shifted frequencies of a transition in 7Li+ have been measured in forward and backward direction. First results confirm relativity and set an improved limit of 2.2 x for deviations from the Lorentz factor 7 s ~ = 1/J1 v2/c2. Ongoing improvements will tighten the limit further. Preliminary investigations indicate that Doppler-type experiments can have unique sensitivity for testing Lorentz/CPT-violating extensions of the Standard Model.