The past two weeks at DESIREE have been dedicated to merged beam experiments with external users from Uppsala University. Just like the railroads, DESIREE is an infrastructure which strengthens connections within Sweden as well as to the world. We spoke with Paul Barklem and Jon Grumer about their experiments and their experience as theorists using a large experimental facility.

Paul Barklem and Jon Grumer take a look beneath the DESIREE storage rings.

Who are you; where are you from?

Paul Barklem and Jon Grumer, from Uppsala University, Sweden.

What is your research in general?

We do research on theoretical atomic physics with applications to astrophysics, especially stellar atmospheres. We apply our results to measuring the abundances of chemical elements in stars, which is important information in many astrophysical problems. For example we can study how the chemical elements have been produced, as well as how our galaxy, the Milky Way, formed.

How will your experiments at DESIREE further your research?

This week we are colliding positive lithium ions with negative heavy hydrogen (deuterium) ions. This process is important in interpreting lithium abundances in stars from spectra. The inferred lithium abundances in stars tell us about the lithium produced in the Big Bang, as well about how stars evolve. The comparison of our theoretical atomic collision calculations with experiment also tests our general understanding of such atomic processes, data for which are often needed in many parts of astrophysics.

Are there any unique capabilities of DESIREE that you are exploiting?

This will be the first time such an experiment has been performed at the low collision energies relevant in stellar atmospheres.

How do you find it to work at the infrastructure?

The staff are extremely friendly, helpful, and competent. As theorists, we are inspired by what has been achieved at DESIREE, and this motivates us to do more and better calculations.