On Sunday, July 5, 2026, Jan Hladký died at the age of 91, shy of his 92nd birthday. A physicist who devoted nearly seven decades to science, he made his mark on the international history of particle physics through his discoveries.
Jan Hladký spent his entire scientific career at the Institute of Physics. He joined it in 1957 as a student in the Cosmic Ray Laboratory in Prague's Karlov and on Lomnický štít, led by P. Chaloupka and part of the cosmic ray group of Prof. V. Petržílka. He helped build cosmic ray detectors, take regular readings from them, and analyze the resulting data — spending long stretches of time on Lomnický štít itself, often in harsh weather conditions.
The journey to Dubna and first scientific awards
After this stage of his career, he turned to particle physics using accelerators. Despite difficulties with his security clearance, caused from 1953 onward by the secret police's interest in him, he was able to travel to the Joint Institute for Nuclear Research (JINR) in Dubna near Moscow in 1963.
There, at the Laboratory of High Energies, he earned the rank of Candidate of Sciences. He took part in several experiments that contributed to the development of particle physics at the time, including the discovery of a new decay of the φ meson into electron-positron pairs and of a new charmed baryon, Λc. He also studied K meson regeneration at what was then the world's largest accelerator, at the Institute for High Energy Physics in Serpukhov.
After returning from Dubna, he led a group of electronic experiments in the High Energy Physics Department at the Institute of Physics and served as a member of the Electronic Experiments Committee under JINR's Scientific Council for High Energies. For his contribution to the discoveries made in JINR experiments, he received the JINR First Prize in Dubna (1969), the Prize of the State Committee for Discoveries under the USSR Council of Ministers (1972), and the Prize of the Czechoslovak Academy of Sciences (1975).
The H1 and ALICE experiments
From 1987, he was a member of the H1 experiment at DESY in Hamburg. He contributed to the development and construction of detectors and later helped build new apparatus for H1. He co-authored numerous results published in international scientific journals, and was also a principal and co-investigator on ČSAV and GAČR grants supporting the H1 experiment.
After the H1 experiment concluded and the HERA accelerator at DESY ended operation, Jan Hladký joined the ALICE experiment at the LHC at CERN, which studies collisions of protons and heavy ions.
Teacher, artist, and author
Doc. Hladký also taught at the Faculty of Mathematics and Physics of Charles University and at the Faculty of Nuclear Sciences and Physical Engineering of the Czech Technical University, where he lectured on particle physics and detector technology.
His interests extended well beyond science. His drawings, made on the spot at prestigious physics conferences, became a graphic feature of numerous conference proceedings. His exhibitions of artwork at scientific institutions were also well received.
In 2018, he published a book, Paměti kosmika (Memoirs of a Cosmic-Ray Researcher), with the Academia publishing house, in which he recounted the history of high-energy particle physics research and the development of international collaboration.