ALPHATRAP

For the measurement of the g-factor of the electron in extremely heavy ions, a novel cryogenic Penning trap, called ALPHATRAP, is currently set up at MPIK. It features an access to the Heidelberg EBIT [1], which can deliver even the heaviest highly charged ions up to ²⁰⁸Pb⁸¹⁺. With these systems it becomes possible to probe QED at the boundary of our knowledge in the most extreme fields. The ions are transported via a beamline including ion-optic elements and diagnostic stations to ALPHATRAP. There, the trap region is surrounded by a liquid-helium cryostat to provide a cryogenic environment. To ensure sufficient vacuum conditions for the storage of highly charged ions despite the connection to the room-temperature vacuum, a cryogenic vacuum valve is developed to cut the beamline off the trap setup.

Besides mechanical differences due to the open system most technical elements can in principal be adopted from the Mainz setup. However, adjustments are necessary for several issues. For instance, the higher charge states of the ions lead to a corresponding systematic shift of the ion frequencies due to the image-charge effect and, thus, a larger trap diameter is needed compared to the Mainz-trap. Another example is the even more complex and extensive detection system, which is currently under development.

Figure 1: The new ALPHATRAP setup. Ions can be injected from the Heidelberg HD-EBIT via a beam-port from the top. The design is based on the Mainz apparatus, but numerous improvements and new technologies have been implemented.

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References

[1]	Optimization of the charge state distribution of the ion beam extracted from an EBIT by dielectronic recombination
	J. R. Crespo López-Urrutia, J. Braun1, G. Brenner, H. Bruhns, A. Lapierre, A. J. González Martı́nez, V. Mironov, R. Soria Orts, H. Tawara, M. Trinczek and J. Ullrich
	Rev. Sci. Instrum. 75, 1560 (2004)

ERC Advanced Grant

This project receives funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme under grant agreement No 832848 - FunI .