XXIII Nuclear Physics Workshop in Kazimierz Dolny to commemorate Professor Janusz Wilczyński

XXIII Nuclear Physics Workshop Marie & Pierre Curie is an annual meeting of scientists involved in research on structure and decays of atomic nuclei organized by the Theoretical Physics Chair at Physics Faculty of the Maria-Curie Skłodowska University (UMCS) in Lublin. This year event was held between September 27 and October 2, 2016 in Kazimierz Dolny. Several tens of scientists from all over the world attended.

NCBJ co-organized this year event to better commemorate work and achievements of Professor Janusz Wilczyński, a world-class expert in nuclear physics. As one of the most outstanding nuclear physicists in Poland he actively participated in numerous research projects accomplished in Poland, initially at the Jagiellonian University in Cracow and in Joint Institute for Nuclear Research in Dubna (Russia), then in Institute for Nuclear Physics (IFJ PAN) in Cracow. From 1980 he was employed by Institute for Nuclear Problems in Świerk, later NCBJ.

The solemn commemorative session held on October 2 was chaired by Professor Krzysztof Pomorski from UMCS. Professor Angelo Pagano from INFN (Catania, Italy) gave the “Janusz Wilczyński: Time scale of nuclear reactions from deep inelastic to projectile-target fragmentation” speech. Professor Rafał Broda from IFJ PAN gave the “Janusz Wilczyński: wisdom and imagination in physics” speech.

Professor Adam Sobiczewski from NCBJ recalls Janusz Wilczyński: Wilczyński’s characteristic feature was that he usually provided very ambitious, original and creative interpretations to experimental results. The interpretations were aimed to better explain mechanisms of heavy-ion reactions. For example, analysing cross sections for creation of compound nuclei he proposed an idea of the “contact force” as some attractive force acting when nuclei surfaces are in touch. The performed droplet-model-based evaluations gave very good results for the critical angular momenta. The “contact force” idea was a starting point for the “proximity force“ ( potential) generalization done later in Berkeley by W.J. Świątecki and his co-workers. That latter concept has been widely used in contemporary nuclear physics up to these days. Professor Wilczyński’s interpretation of the deeply inelastic scattering reaction on the ground of the classical deviation function for the case of some non-conservative forces was also very innovative and creative. That interpretation made possible to tightly relate dissipation of relative movement kinetic energy with deflection angle. A 2D chart invented by Wilczyński was very helpful here. It presented double differential cross section vs. energy and exit angle for the given reaction product. Te chart is known in scientific literature as the “Wilczyński’s chart”. Many experimental data he brought back from his numerous stays abroad (ZIBJ, Dubna, 1963-66 and 1967-72; Niels Bohr Institute, Copenhagen 1972-74; Institute de Physique Nucleaire, Orsay 1976; Kernfysisch Versneller Instituut, Groningen, 1977-79 and 1989-91; National Superconducting Cyclotron Laboratory in East Lansing and  Lawrence Berkeley National Laboratory in Berkeley, 1984-86  was analysed home. Many of his papers are now included to the canon of physics of the reactions with heavy ions. He published more than 160 papers cited more than 3,500 times. The current value of the Hirsch index is 31. A significant fraction of the papers was co-authored by his spouse, Professor Krystyna Siwek-Wilczyńska. His language was simple, accessible yet very precise. He was awarded with numerous awards, prizes and honourable mentions, including Polish Physical Society (PTF) award (1976), ZIBJ Dubna Scientific Council award (1976), National Council for Peaceful Utilization of Atomic Energy award (1978), Golden Cross of Merit (1989), the Wojciech Rubinowicz PTF award (1992), Knight's Cross of the Polonia Restituta Order (2015).

Prof. Wilczyński was among Polish nuclear physicists most renown in the world. He passed away on October 22, 2015 in Warsaw. Till the very end of his life his mind was clear, he was working with his wife and a PhD student on their last paper.

Bronisław Komorowski, the then President of the Republic of Poland awarded him in 2015 with Knight's Cross of the Polonia Restituta Order. Since for health reasons he was not able to come in person to collect the order, now Professor Krzysztof Kurek, NCBJ Director General, solemnly handed it to Professor Krystyna Siwek-Wilczyńska, the widow.