Simulations of antihydrogen

SNIC 2018/3-9


SNAC Medium

Principal Investigator:

Svante Jonsell


Stockholms universitet

Start Date:


End Date:


Primary Classification:

10302: Atom and Molecular Physics and Optics



The ALPHA antihydogen experiment was in November 2010 able to report the first successful attempt to catch antiatoms in a magnetic trap. This achievement, reported in Nature, has received a lot of attention, both in news media, popular since, and within the physics community. For example, Physics World listed this as the most important progress in Physics 2010, and the American Physical Society had in on its top ten list. More recently we made the first antimatter spectroscopy between hyperfine states of antihydrogen. The long-term goal of ALPHA and other antihydrogen experiments is to test fundamental symmetries of nature by comparing matter and antimatter atoms. Primarily, ALPHA aims at high-resolution spectroscopy of antihydrogen, for instance on the 1s-2s line which has been measured to an accuracy of one part in 10^14 in ordinary hydrogen. Another possibility is to compare the gravitational interaction of matter and antimatter. All studies of this sort require the antiatoms to be held in an atom trap for times long enough to perform the studies. This is a challenge since antimatter is destroyed when it meets ordinary matter. Therefore the atom trap consists of varying magnetic fields, where the atoms are confined near the minimum of the field. However, the trap is very shallow, antiatoms with an energy greater than about 0.5 Kelvin will escape from the trap. Since typical energies in the experiment are much higher than this, only a small fraction of the antihydrogen atoms created can actually be trapped. During 2016 we managed to do the first 1s-2s transitions. Behind this success was an increase in the trapping efficiency by about two orders of magnitude. This shows the importance of simulations of this type. However, as the experiments are being improved and new experiments starting, there is a need for continued numerical support. For the future I intend to focus on large scale simulations of antiprotons stopping in a positron plasma. Dynamics of trapped ground-state antihydrogen may also be studied. This is necessary to understand how the antiatoms react to applied fields, such as microwaves or lasers. Additionally, I perform calculations of antihydrogen and antiprotons interacting with ordinary atoms and ions. This is important since, even though one strives to create a good vacuum in the trapping region, there is always some background gas present.