Towards a new test of time dilation [Elektronische Ressource] : laser spectroscopy on lithium ions stored at a velocity of 33.8 % of the speed of light / presented by Christian Novotny

Novotn

Sujets

• Physik

Informations

• Publié par: johannes_gutenberg-universitat_mainz
• Publié le: 01 janvier 2008
• Nombre de lectures: 6
• Langue: English
• Poids de l'ouvrage: 19 Mo

Extrait

Towards a new test of time dilation
Laser spectroscopy on lithium ions
stored at a velocity of 33.8 % of the speed of light

Dissertation
for the degree of
Doctor of Natural Sciences



submitted to the
Department of Physics, Mathematics and Computer Science
of the Johannes Gutenberg-Universität in Mainz







presented by
Dipl.-Ing. (FH) Christian Novotny
born in Hanau

Date: 29.08.2008




















Date of oral examination:
27.11.2008



ABSTRACT
In this thesis results towards a new test of time dilation given by the theory of special
relativity (SR) are presented. The performed experiment follows the measurement
principle of Ives and Stilwell which states: time dilation can be accurately tested by the
simultaneous measurement of the Doppler-shifts of a clock transition both with and
7 +against the clock’s motion. The clocks are Li ions which were stored at a velocity ()
of 33.8 % of the speed of light (c) in the experimental storage ring (ESR) at the
+Gesellschaft für Schwerionenforschung, Darmstadt. The used Li ions were in the
metastable ground state where they exhibit a strong electric dipole transition in the
optical region (548.5 nm ) and the hyperfine-structure allows optical double resonance
spectroscopy. By means of such a spectroscopy scheme the Doppler-shifts can be
measured without limitations from Doppler-broadening, caused by the velocity
distribution of the ions in a storage ring. Consequently, both time dilation as well as the
ion velocity can be extracted with high accuracy for a test of the predictions of SR.
A fluorescence detection system with two counter propagating laser beams (at
= 780 nm, nm = 386 ) which are aligned collinearly to the ion beam was set up. 1 2
To achieve a robust control of the laser frequencies required for the beam times, a
redundant system of frequency standards consisting of rubidium spectrometer, an iodine
spectrometer, and a frequency comb was developed. The laser setup includes adequate
frequency references for each laser and allows resonant (laser) excitation with and
against the flight direction of the ions. At the experimental section of the ESR, an
automated laser beam guiding system for exact control of polarisation, beam profile,
and overlap with the ion beam, as well as a fluorescence detection system were build
up.
During the first experiments, the generation, the acceleration and the lifetime of the
metastable ions were investigated at the GSI facility. Further the velocity of the stored
ion beam has been measured directly, for the first time, via the Doppler effect, and thus
the effective voltage of the electron cooler.
In the following step the first sub-Doppler spectroscopy signals from an ion beam at
33.8 %c could be recorded. Here, the excitation frequencies in the laboratory frame p,a
( )are shifted with respect to the rest frequencies of the ions by =

1± 1,2 p,a 1,2
when moving with =/c. If special relativity holds
=
, i.e. 1 2 a p
2 2 =1(1 ). In test theories hypothetical deviations from special relativity are
described by a series of parameters ( , , …) which are weighted by even powers of 2
. These Lorentz violations can be identified by a slightly modified time dilation factor
2 4 =
(1+ 2

+ ( + 2
)
+ ...). MS 2