A new measurement of the relativistic Doppler shift

Abstract

It is widely believed that laser techniques will make possible a new generation of interesting tests of the fundamental concepts underlying contemporary physical thought.Given the recent progress in laser frequency stabilization and in the achievement of ever higher spectral resolution, one may imagine laser devices ultimately serving as quantum frequency standards in a number of interesting and fundamental experiments. Several such experiments being actively considered are: more precise measurements of the gravitational redshift, more sensitive tests for spatial anisotropy, and frequency comparison experiments designed to look for a secular drift of the frequency ratio of atomic clocks based on different physical principles. But happily enough, sometimes the available techniques are sufficient to make interesting measurements even before the great Laser Millenium arrives. In this paper we report on our high precision measurements of the relativistic (or "transverse") Doppler effect using laser saturated absorption techniques on a high speed atomic beam. Previous optical measurements of the effect I have used comparable beam speeds, but have been limited by normal Doppler broadening to a few percent accuracy. The MSssbauer experiments 2 obtained similar accuracy by using very high spectral resolution, but were limited by the relatively low speed attainable with a mechanical rotor. Meson experiments 3 have wonderful v/c values, b~t extreme precision is hard to achieve in measuring the time of flight and the decay length. Our experiment is based on the observation that the particles observed in saturation spectroscopy are free of first-order Doppler shifts and broadening. The transverse effect, however, is more persistent. It *NRC-NBS Postdoctoral Fellow. "~Staff ~ember, Laboratory Astrophysics Division, National Bureau of Standards.

Missing Transverse-Doppler Effect in Time-Dilation Experiments with High-Speed Ions

“…It is noted that time-dilation predicted by special relativity (SR) has been verified with a number of experiments starting with the classical experiment using Hydrogen canal rays by Ives and Stilwell [2]. More recent experiments have evaluated the time-dilation effect by using Doppler-shifted lasers to excite transitions in highspeed Neon (Ne) and Lithium (Li) ions [1,3]- [6]. A challenge in using high-speed ions is the presence of substantial Doppler broadening, which is resolved by using two lasers with different Doppler shifts that affect ions at a unique speed.…”

Einstein’s time dilation and the relativistic Doppler shift: avoiding the pitfalls

“…Further experiments by the same experimentalists extended the tested range of velocities [3]. A remarkable improvement in prevision was reported by Snyder and Hall [25] by using narrow-band dye lasers and atom spectroscopy.…”

Lorentz violation in high-energy ions

“…For example, Doppler shift experiments such as the Ives-Stillwell experiment are sensitive to Lorentz violating terms in standard model extension [1,2]. This renews the interest in experiments on high-speed ions that check for Lorentz violations by experimentally measuring potential deviations in the time dilation predicted by special relativity [7][8][9][10][11].…”

“…More recent experiments [7][8][9][10][11] have evaluated the time-dilation effect by using Doppler-shifted lasers to excite transitions in high-energy neon (Ne) and lithium (Li) ions and then observe the emissions at high ion speeds-as high as v = 0.338c in [11].…”