Search

We present preparatory measurements for an improved test of time dilation at the experimental storage ring (ESR) at GSI in Darmstadt. A unique combination of particle accelerator experiments and laser spectroscopy is used to perform this test with the highest precision. 7Li+ ions are accelerated to 34% of the speed of light at the GSI Helmholtzzentrum für Schwerionenforschung and stored in the experimental storage ring. The forward and backward Doppler shifts of an electric dipole transition of these ions are measured with laser spectroscopy techniques. From these Doppler shifts, both the ion velocity β = ν/c and the time dilation factor [IMG] can be derived for testing Special Relativity. Two laser systems have been developed to drive the 3S1→3P2 transition in 7Li+. Moreover, a detector system composed of photomultipliers, both to monitor the exact laser ion beam overlap as well as to optimize fluorescence detection, has been set up and tested. We investigate optical-optical double-resonance spectroscopy on a closed Λ-type three-level system to overcome Doppler broadening. A residual, broadened fluorescence background caused by velocity-changing processes in the ion beam is identified, and a background subtraction scheme implemented. At the present stage the experimental sensitivity, although already comparable with previous measurements on slower ion beams at the TSR storage ring that led to [IMG] < 8.4 × 10-8, suffer from a poor signal-to-noise ratio. Modifications of the ion source as well as the detection system are discussed that promise to improve the sensitivity by one order of magnitude. Nous présentons des mesures préparatoires de la dilatation du temps à l'anneau de stockage d'ions lourds ESR au GSI de Darmstsdt. Nous utilisons une combinaison unique d'accélérateur de particules et de spectroscopie laser pour compléter ce test avec la plus haute précision. Des ions 7Li+ sont accélérés jusqu'à 34 % de la vitesse de la lumière au GSI Helmholtzzentrum für Schwerionenforschung et conservés dans son anneau de stockage (ESR). Nous mesurons par spectroscopie laser l'effet Doppler avant et arrière d'une transition dipolaire électrique dans ces ions. À partir de ces déplacements Doppler, nous pouvons obtenir la vitesse des ions β = v/c et le facteur de dilatation du temps [IMG] pour tester la relativité restreinte. Deux systèmes lasers ont été développés pour exciter la transition 3S1→3P2 dans le 7Li+. De plus, nous avons développé et testé un système de détection composé de photomultiplicateurs pour mesurer à la fois le chevauchement exact du faisceau d'ions et pour détecter la fluorescence optimisée. Nous analysons la spectroscopie à double résonance optique-optique sur un système fermé à trois niveaux de type Λ afin de contrebalancer l'élargissement Doppler. Nous identifions un fond élargi résiduel de fluorescence, causé par le changement de vitesse du faisceau d'ions et nous avons appliqué une procédure de soustraction du fond pour le contrecarrer. À cette étape-ci, notre précision expérimentale souffre d'un mauvais rapport signal sur bruit, même si elle est comparable à une mesure déjà effectuée avec des faisceaux d'ions plus lents à l'anneau de stockage TSR qui a donné une valeur [IMG] < 8.4 × 10-8. Nous proposons des modifications à la source d'ions et au système de détection qui promettent d'améliorer la sensibilité par un ordre de grandeur. [ABSTRACT FROM AUTHOR]

We present the concluding result from an Ives-Stilwell-type time dilation experiment using 7Li+ ions confined at a velocity of β = v /c = 0.338 in the storage ring ESR at Darmstadt. A A-type three-level system within the hyperfme structure of the 7Li+3S1 → 3P2 line is driven by two laser beams aligned parallel and antiparallel relative to the ion beam. The lasers' Doppler shifted frequencies required for resonance are measured with an accuracy of < 4 × 10-9 using optical-optical double resonance spectroscopy. This allows us to verify the special relativity relation between the time dilation factor y and the velocity β, γ√ 1 - β>2 = 1 to within ±2.3 × 10-9 at this velocity. The result, which is singled out by a high boost velocity β, is also interpreted within Lorentz invariance violating test theories. [ABSTRACT FROM AUTHOR]

We report on a new experimental approach for the Doppler correction of X-rays emitted by heavy ions, using novel metallic magnetic calorimeter detectors which uniquely combine a high spectral resolution with a broad bandwidth acceptance. The measurement was carried out at the electron cooler of CRYRING@ESR at GSI, Darmstadt, Germany. The X-ray emission associated with the radiative recombination of cooler electrons and stored hydrogen-like uranium ions was investigated using two novel microcalorimeter detectors positioned under 0 ∘ and 180 ∘ with respect to the ion beam axis. This new experimental setup allowed the investigation of the region of the N, M → L transitions in helium-like uranium with a spectral resolution unmatched by previous studies using conventional semiconductor X-ray detectors. When assuming that the rest-frame energy of at least a few of the recorded transitions is well-known from theory or experiments, a precise measurement of the Doppler shifted line positions in the laboratory system can be used to determine the ion beam velocity using only spectral information. The spectral resolution achievable with microcalorimeter detectors should, for the first time, allow intrinsic Doppler correction to be performed for the precision X-ray spectroscopy of stored heavy ions. A comparison with data from a previous experiment at the ESR electron cooler, as well as the conventional method of conducting Doppler correction using electron cooler parameters, will be discussed. [ABSTRACT FROM AUTHOR]