Prof. Stanisław Grzegorz Rohoziński – in memoriam

Stanisław Grzegorz Rohoziński was born on July 30, 1936 in Warsaw, although the family came from the distant borderlands – Żytomierszczyzna. His father, who was a colonel in the Polish Army, orphaned the family in December 1938. Grzegorz spent the difficult years of the war in Warsaw with his mother and three sisters. After the Warsaw Uprising, they were supposed to be deported to Germany, but they managed to escape from the transport and, as a result, the family spent the post-war years in Gdynia, where Grzegorz attended school […] He graduated from the Faculty of Mathematics and Physics of the University of Warsaw in 1958, writing his master’s thesis Two-photon annihilation of the electron-positron pair of any polarity under the supervision of Professor Józef Werle, while his PhD thesis entitled Green’s function methods in nuclear matter theory he defended  under the supervision of Professor Iwo Białynicki-Birula in 1966.   Already during his studies, on October 1, 1957 year, he became an employee of  Faculty of Physics , Warsaw University as a deputy assistant. He remained faithful to the Faculty, or more precisely to the Institute of Theoretical Physics, going through all levels of academic career, from the aforementioned deputy assistant, through the positions of assistant (since October 1, 1958), senior assistant (since October 1, 1960), assistant professor (October 1, 1966). r.), senior lecturer (1968-1974) and again assistant (1974-1983). In the years 1 September 1983 – 30 September 1990 he worked as an associate professor at the Institute of Theoretical Physics, and from 1 October 1993 he was employed as an associate professor. Grzegorz obtained the academic title of professor in 1991, and from October 1, 1993 he was employed as a full professor. He was not only an excellent physicist, but also a highly respected lecturer. He conducted a number of course lectures in various fields of theoretical physics, including numerous monographic lectures. However, he was above all an outstanding organizer – the community of the Faculty remembered him as an excellent deputy director (1987-1993) and then director of the Institute of Theoretical Physics (1993-2005).

In his scientific work, Grzegorz was an honest perfectionist. He solved successive problems of theoretical nuclear physics in depth and completely. His main research area was the collective excitation of atomic nuclei. In particular, he was interested in nuclear states characterized by quadrupole and octupolar shapes. He was the author of fundamental papers and review articles on complete solutions to quantum equations of motion for quadrupole shapes. In particular, the works discussed such motions not only in the language of nuclear models, but also with the use of their microscopic derivations. He concluded these works by presenting the first meaningful formalism describing quadrupole excitation of odd nuclei, where collective motion must be explicitly coupled with a spinor characterizing the odd particle state.

Grzegorz devoted a large part of his scientific activity to cooperation with experimentalists. His last published work is dated August 13, 2021 and deals with non-axial shapes in the recently measured states of an exotic samarium isotope with a mass number of 140. But in 1974 he formulated a model, recently called the “Warsaw solution” or “Warsaw model” interpreting the properties of collective quadrupole excitations nucleus at 50 <Z, N <82. His extraordinary character and the ability to patiently translate even the complex notions of the theory of nuclear structure made Grzegorz an excellent collaborator, friend and mentor of experimentalists. The latest joint work of the experiment and theory on the magnetic moment of chiral bands in the 128Cs nucleus is at the last stage before being sent to the editorial office.

Jacek Dobaczewski, Wojciech Satuła, Julian Srebrny