Recent news

ERC Starting Grant for Alban Kellerbauer

Alban Kellerbauer has won a Starting Grant of the European Research Council in the fourth round of calls (StG 2010). The grant with a funding volume of more than 1.1 million euros over five years was awarded for the work on laser cooling of negative ions.
The European Research Council (ERC) was set up in 2006 to support investigator-driven frontier research. Its main aim is to "stimulate scientific excellence by supporting and encouraging the very best, truly creative scientists, scholars and engineers to be adventurous and take risks in their research." The scientists are encouraged to go beyond established frontiers of knowledge and the boundaries of disciplines. The ERC complements other funding activities in Europe such as those of the national research funding agencies, and is a flagship component of the 'Ideas Programme' of the European Union's Seventh Research Framework Programme (FP7).

Article on Os⁻ hyperfine structure spectroscopy published

The laser cooling of negative osmium will require the confinement of a cloud of Os⁻ ions in a Penning trap. In the strong magnetic field of the trap, the cooling transition line will split due to the Zeeman effect. The knowledge of the exact Zeeman structure is crucial, because it guides the choice of the sublevel used for cooling and determines whether the transition is closed or whether the excited state may decay to intermediate states, requiring a repumping laser. Since the Zeeman splitting depends on the angular momentum quantum numbers, we have measured the hyperfine structure of the bound–bound transition in two Os⁻ isotopes with a non-zero nuclear spin. This has allowed us to determine the previously unknown total angular momentum of the excited state and calculate the Zeeman structure of ¹⁹²Os⁻.


Reference: A. Fischer et al., “First optical hyperfine structure measurement in an atomic anion,” Phys. Rev. Lett. 104 (2010) 073004.

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Arne Fischer's graduate thesis submitted

With only one more exam to go, Arne Fischer is fast approaching the end of his graduate studies and the award of his Diplom degree. He today submitted his graduate thesis on the spectroscopy of the osmium anion, a major contribution to the first experimental results and the paper in which they are presented (see the previous News item). In his thesis, Arne details the design and construction of the collinear spectroscopy setup and his development of an electric-field detacher, with which the sensitivity of the apparatus was increased by about two orders of magnitude.

Reference: A. Fischer, “Laser spectroscopy on the negative osmium ion,” Diplom thesis, University of Heidelberg (2009).

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Article on Os⁻ spectroscopy published

With the long-term goal of laser cooling a negative ion for the first time, we have thoroughly investigated the only known electric-dipole transition in an atomic anion by collinear laser spectroscopy. A publication on the first results, concerning the transition frequency and resonant cross-section, has just appeared in Physical Review Letters. Using a unique combination of laser excitation and electric-field neutralization, we have improved the previous transition frequency measurement by more than a factor 100. Our value for the Einstein A coefficient is lower than previously found, suggesting that pre-cooling of Os⁻ to liquid-helium temperature may be required in order to achieve reasonable laser cooling times of a few minutes.


Reference: U. Warring et al., “High-resolution laser spectroscopy on the negative osmium ion,” Phys. Rev. Lett. 102 (2007) 043001.

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