Apparatus for Trapping and Spectroscopy of Atoms

• Subject Area: Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas
• Term: Funded in 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 460938875

Our main goal is the laser spectroscopy of trapped hydrogen (H), deuterium (T), tritium (T) and lithium-6 and -7 (Li). These precise measurements with an accuracy of better than 1 kHz yield the isotope shift, which can be used to determine the difference of the nuclear charge radii.For tritium, this will lead to a 400fold improved value of the triton charge radius. For this, one needs cold, magnetically trapped T atoms. Hydrogen and Antihydrogen have already been trapped, and laser spectroscopy with the envisaged precision has been performed. The methods employed there, however, can not be applied to tritium. We therefore plan to cool and trap of H, D, and later T using an ultra-dense cloud of cold Li atoms, trapped in a magneto-optical trap (MOT).To this end, we have already built a MOT setup for Li and another apparatus which produces a cryogenic beam of H atoms. Both, cold Li and cold H can now be subjected to laser spectroscopy, using our existing laser systems.The main missing ingredient is a device for precise measurement and control of our lasers (frequency comb). This will enable us to find the well-known 1S-2S resonance in atomic hydrogen, and to optimize the H apparatus. Then we plan to embed the Li apparatus into our H apparatus, to be able to cool and trap the H atoms using the cold Li gas. We then plan to perform spectroscopy in H and D and, by comparison with the 100fold better measured literature values, study the systematic effects originating from our trap and the Li MOT. Finally, we plan to trap and measure T atoms, resulting in a 400fold improved charge radius of the triton.The requested frequency comb will also used at the Li MOT apparatus to measure the Li-6/7 isotope shift using cold Li for the first time, yielding superior precision. Finally, the frequency comb will help us calibrate a laser being developed for the laser spectroscopy of muonic hydrogen which should yield a 100fold improved value of the magnetic "Zemach"-radius of the proton.The overarching goal of all of these experiments in my group are the measurements of nuclear observables (charge radii, their differences, and magnetic radii) of the lightest nuclei using laser spectroscopy of light atoms.

• DFG Programme: Major Research Instrumentation
• Major Instrumentation: Gerät zum Fangen und zur Spektroskopie von Atomen
• Instrumentation Group: 5730 Spezielle Laser und -Stabilisierungsgeräte (Frequenz, Mode)
• Applicant Institution: Johannes Gutenberg-Universität Mainz
• Leader: Professor Dr. Randolf Pohl