New Method to Measure the Relativistic Doppler Shift: First Results and a Proposal

The fast-atom-laser collinear beams technique has been used to measure the relativistic Doppler effect to an accuracy comparable to the best previous experiments (5 parts in ${10}^3$). Improved calibration data and a similar technique, but employing two lasers, is proposed, which should improve the test of time dilatation by at least another factor of 10.