Dr. Johann Zmeskal

Hannes Zmeskal passed away on July 23, 2024 after a short severe disease. With Hannes we lose an unparalleled experienced researcher in the field of exotic atoms and experimental low-energy hadron physics. His work manifested in many important publications. He was a driving force in experiments on muon/pion experiments and low-energy kaon nuclear physics. His success in acquiring third party funding is remarkable – he was principal investigator in projects of the Austrian Science Fund and in the European research activities like Strong2020.
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I know him since 1980 when I joined a research group at Paul Scherrer Institute (SIN at this time) in Switzerland.  Johann Zmeskal was a specialist of all kind of cryogenic targets and detector systems used in experiments on muon catalyzed fusion, the nuclear  fusion is resulting from the strong binding of 
two deuterons or deuteron-triton using a negatively charged muon which is released after the fusion process with a high probability and can start another fusion cycle. The finding of hyperfine effects in the molecular formation was topic of his PhD work - a big success and it is published in Phys. Rev. A.
He was member of many Collaborations like SIDDHARTA, ASACUSA and PANDA. In the PANDA experiment he contributed to the target system from the beginning but he was also working on the time-of-flight system. Due to his experience in cryogenic and ultrahigh vacuum systems he contributed to low-energy antiproton physics in experiment at the antimatter facility of CERN.
He was a leading figure in the experiments DEAR, SIDDHARTA and SIDDHARTA2 at Laboratori Nazionali di Frascati of INFN from the beginning of the electron-positron collider DAFNE operation.
Hannes Zmeskal was finally co-spokesperson of the very successful SIDDHARTA2 experiment on kaonic deuterium which is after the kaon-hydrogen experiment a key experiment to study the strong interaction at lowest energies  in an exotic atom with strangeness.
Hannes Zmeskal with his patient, kind and optimistic nature was always a calming pole in any of his many experiments. It has to be highlighted that Hannes was an extremely good mentor for a new generation of researchers.
Loved by all who knew him, he will be missed.

Johann Marton