Professor Marian Mięsowicz (1907-1992)

Prof. Marian Mięsowicz was born in the city of Lvov on November 21,1907, and died in Cracow on April 5, 1992. He read Physics at the Jagiellonian University (UJ) in Cracow and graduated in 1930 with a PhD degree for his thesis entitled "On Short and Slowly Damped Electromagnetic Waves".

In 1934, as an assistant of Professor Jeżewski in the Physics Department at the Cracow University of Mining (now AGH), Marian Mięsowicz started off an independent and pioneering research on hydrodynamics of liquid crystals. His works showed that nematic liquid crystals exhibited at least three viscosities, depending on the mutual orientation of the flow and the average molecular orientation. He carried out the first accurate determination of anisotropic viscosities and introduced viscosity coefficients known in the scientific literature as the Mięsowicz coefficients. His works had strong impact on further development of dynamical theory of nematic liquid crystals and are widely recognized as fundamental for contemporary investigations in this field.

At the end of 1930s, Marian Mięsowicz took a scientific interest in nuclear physics. He built an electronic apparatus with Geiger-Mueller counters for studies of cosmic rays. Mięsowicz was interested in the studies of the penetrating component of cosmic rays. The counter telescope was to be placed in a stratospheric balloon. The launch of the balloon was to take place in a valley in the Polish Tatra mountains. Unfortunately, while filling the balloon with hydrogen there was a sudden explosion, and as a consequence, the balloon burnt up. Luckily, the apparatus survived but further plans were interrupted with the outbreak of the Second World War. In 1948 Prof. Mięsowicz began to build an experimental apparatus to study extended air showers in the Salt Mine in Wieliczka near Cracow. The measurements deep undeground confirmed the observation of a penetrating component of cosmic rays and a presence of weakly ionizing isotropic component strongly absorbed by lead, which was attributed to the natural radioactivity of the surrounding medium, opposite to the postulated interpretation of interactions of neutrinos. This observation initiated a collaboration with geologists and a development of Polish nuclear geophysics. This correct interpretation was a great success of the Cracow group. A manuscript of the paper was sent to Physical Review and published in 1950. This publication, cited many times in journals and books, was a cornerstone of a broad international collaboration set up by the Cracow high energy physics community, a collaboration continued up to the present time.

After finishing the studies in Wieliczka Prof. Mięsowicz decided to change the experimental technique and to use nuclear emulsion for investigation of cosmic ray interactions by studying electromagnetic showers of very high energy, of the order of 10^12 eV. The inconsistency of the energy spectrum of electron pairs with the Bethe-Heitler prediction was noticed. This was the first experimental observation of the coherence effect predicted by Landau-Feinberg-Pomeranczuk theory. Another new electromagnetic effect, predicted by the Soviet physicist Chudakov, was also observed: a reduction of ionization at the origin of very high energy electron pairs. Studies of electromagnetic cascades led to an observation of jets, an effect of multiparticle production in interactions with emulsion nuclei. Systematic studies of the observed collisions showed an evidence of correlated particles, "clusters", called by G. Cocconi "fire-balls" and led to the formation of the "fire-ball model". Looking back one could say that it was the first attempt to separate from the large number of produced particles groups of correlated particles: jets. Another observation based on nuclear interaction of cosmic rays, a deficit of the number of secondary particles produced in the collisions in comparison with the predictions from the model of internuclear cascade, led to a concept of noninteracting fireball or as it was called later, "a formation zone". The multiparticle production in nuclear interactions became a "Cracow topic", still carried on by both experimentalists and theoreticians.

Prof. Mięsowicz played an important role in the organization of science in Poland. He was elected a member of the Polish Academy of Sciences (PAN), of which he was vice-president in 1969-1977. In 1989 he was elected a member of the resuscitated Polish Academy of Arts and Sciences (PAU). In 1972-1980 he was a member of Polish Parliament. Professor Mięsowicz was a laureate of several prestigious Polish prizes such as the State Prize of the First Degree (1964), the Special State Prize (1979) and the Alfred Jurzykowski Prize in New York. He was awarded the honorary doctoral degrees by the Jagiellonian University and the AGH University of Science and Technology.

His deep interest in physics, a courage and vision to go to new physics fields and experimental techniques as well as his great personality strongly influenced the development of high energy physics in Poland. He was also one of the most instrumental persons in starting a successful international collaboration of Polish high energy physicists.

Grazyna Nowak,

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