International Conference on EXotic Atoms and Related Topics

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Earlier this month EXA2021 took place online and brought experts together from around the world to discuss the latest developments on EXotic Atoms (EXA) and related topics. Over 100 delegates participated in the weeklong event whereby invited speakers presented their R&D during plenary sessions. Poster sessions on the Thursday allowed 40 researchers to present and discuss their work with colleagues in individual breakout rooms.

EXA is a series of international conferences which takes place every 3 year with this edition taking place online and being organized by AVA Partner Stefan Meyer Institute (OEAW) for Subatomic Physics of the Austrian Academy of Sciences. The conference series focusses on muonic, pionic, kaonic, and antiprotonic atoms and related topics. AVA Coordinator Prof Carsten P Welsch (University of Liverpool) has been a member of its International Advisory Committee.

The scientific program comprised topics such as: Antihydrogen (CPT and gravity), Precision experiments with cold neutrons, Hadron physics with antiprotons, and Future facilities and instrumentation. The week opened with plenary talks including Is the proton charge radius puzzle solved (Prof Randolf Pohl) and Measurement of the positron fine structure (Prof David Cassidy). Talks on subsequent days focused on various topics such as Muon g-2 (Status of theory and experiment), Laser cooling of antihydrogen atoms (ALPHA collaboration), Measurements of hadron-hardon interactions (ALICE), and Low-energy kaon-nuclei interactions studies (experiments at DAΦNE and J-PARC). Slides of these and other talks can be found on the event’s website.

In one of the virtual poster rooms, AVA Fellow Markus Wiesinger presented his poster followed by a Q&A discussion with other EXA2021 participants.

A delegation from AVA also attended this conference and one of the Fellows, Markus Wiesinger, presented his work during the poster session. Markus, based at the Max Planck Institute for Nuclear Physics and a member of the BASE collaboration, has been working on advanced cooling techniques for protons and antiprotons in penning traps with the aim of improved measurements of the proton and antiproton magnetic moment. This was also the focus of his poster presentation Sympathetic Cooling of Single Protons (and Antiprotons), which is based on work recently published in Nature.

AVA Steering Committee member Prof Eberhard Widmann (OEAW) and Chair of EXA2021 said: “This instance of the EXA conference was special since – due to the Covid pandemic – it was held in an unusual format: not only was it accessible by video only, but we also decided to have just 4-5 talks a day to make it easier for participants from many continents to attend virtually. Likewise, the poster session was held remotely in parallel virtual rooms between which participants could freely move. It was the first time for us to use this format, and in my opinion, it was very successful as indicated by the number of participants, which was at the same level of previous in-person issues of EXA”.


The proceedings of the EXA2021 will be published in the European Physical Journal Web of Conferences: