Collinear apparatus for laser spectroscopy overcomes systematic uncertainty limits
Collinear apparatus for laser spectroscopy overcomes systematic uncertainty limits lead image
Collinear laser spectroscopy is commonly used for characterizing the properties of short-lived exotic isotopes. However, its precision is limited by frequency and voltage measurements, as well as beam superposition and collisions with residual gas.
To overcome these limitations, König et al. employed a frequency comb – a device that connects laser frequencies with an atomic clock. Along with the use of two laser systems superimposed with the ion beam in opposition geometry, the group improved the precision of the experiments.
“We investigated singly-charged barium and calcium ions. These reached a so-far unprecedented accuracy for collinear measurements and even outperformed ion trap measurements on the dipole-allowed transitions in these ions, which allowed us to precisely test atomic theory,” said author Kristian König.
The high performance allowed them to measure the electrostatic potential used for accelerating the ion beam at the metrological level. Besides frequency measurements with the comb, the applied two-chamber pump-and-probe scheme ruled out systematic contributions and lead to an increase in accuracy by more than two orders of magnitude.
“Several approaches to employ the collinear technique for high-voltage measurements were realized before, but all were limited by systematic effects originating in the setup and the method,” said König. “Therefore, we have tried to design an improved system to overcome this.”
The authors look to further optimize the apparatus. They are developing a buffer-gas cooled laser-ablation source to widen the spectrum of available ion species. According to simulations, this source should further improve the quality of the beam.
Source: “A new Collinear Apparatus for Laser Spectroscopy and Applied Science (COALA),” by K. König, J. Krämer, C. Geppert, P. Imgram, B. Maaß, T. Ratajczyk, and W. Nörtershäuser, Review of Scientific Instruments (2020). The article can be accessed at https://doi.org/10.1063/5.0010903 .
