Abstract
The ALPHATRAP experiment at the Max-Planck Institute for Nuclear Physics in Heidelberg aims at probing the validity of quantum electrodynamics in extremely strong electromagnetic fields. To this end, ALPHATRAP will determine the value of the magnetic moment, or the g-factor, of the electron bound in highly charged ions. Quantum electrodynamics predicts this value with extraordinary precision. As the bound electron in highly charged ions is exposed to the strongest fields available for high-precision spectroscopy in the laboratory, reaching up to 1016 V/cm in hydrogenlike lead 208Pb81+, a comparison of the theoretical prediction with a measured value can yield the most stringent test of the Standard Model in strong fields. The targeted precision of eleven digits or more can be achieved by storing single highly charged ions in a cryogenic Penning trap, where its eigenfrequencies can be determined with ultra-sensitive electronics to highest precision. Additionally, the spin state can be non-destructively determined using the continuous Stern–Gerlach effect, allowing spectroscopy of the Larmor precession. ALPHATRAP is constructed to enable the injection and the storage of externally produced ions. The coupling to the Heidelberg EBIT gives access to even the heaviest highly charged ions and thus extends the available field strength by more than two orders of magnitude compared to previous experiments. This article describes the technical architecture and the performance of ALPHATRAP and summarises the experimental measurement possibilities.
Highlights
The Standard Model (SM) of physics describes the interactions of particles via the four fundamental forces – electromagnetic, weak and strong interaction as well as gravitation
As the bound electron in highly charged ions is exposed to the strongest fields available for high-precision spectroscopy in the laboratory, reaching up to 1016 V/cm in hydrogenlike lead 208Pb81+, a comparison of the theoretical prediction with a measured value can yield the most stringent test of the Standard Model in strong fields
The Alphatrap experiment is a next-generation setup aiming to probe the boundaries of validity of quantum electrodynamics and the Standard Model of Physics in the strongest fields
Summary
The Standard Model (SM) of physics describes the interactions of particles via the four fundamental forces – electromagnetic, weak and strong interaction as well as gravitation. By measuring the magnetic moment in different charge states of one isotope, it becomes possible to largely cancel the influence of the nucleus and to compare the measurement with the most precise quantum-electrodynamical calculations [11] This will yield a unique opportunity to perform the most sensitive test of the validity of the SM in extremely strong electromagnetic fields. A nuclear magnetic resonance measurement [14] yielded a new value for the nuclear magnetic moment of bismuth, which recovered consistency with theory, at the cost of a larger uncertainty This yields a further strong motivation to further investigate the HFS in heavy HCI with higher precision, and to perform direct measurements of the nuclear magnetic moments, which would eliminate the major source of uncertainty from the BS-QED test. Precision is an important contribution for other precision tests of the SM with atomic systems
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
