References - Bogoliubov Laboratory of Theoretical Physics - JINR

he joined the group of prof. Przemys̷law Iwo Zieliński at the Institute of Nuclear Research
(now the So̷ltan Institute for Nuclear Studies). During early years, in the 60’s and
70’s, he collaborated with physicists from University College London, Dubna, Rutherford
Laboratory and Fermilab.
Since 1981 Jan participated in a series of experiments at CERN with muon beams
(EMC, NMC, SMC and COMPASS) using deep inelastic scattering to study the internal
structure of the nucleons. In the early 80’s he set-up a group of Polish physicists involved
in the muon experiments. Jan participated in the ground-breaking discovery of the EMC
that the quark spins contribute little to the nucleon spin (coined as ’the nucleon spin
crisis’). He was a key contributor to the precise studies of the structure functions by the
NMC, resulting among others in observation of symmetry breaking in unpolarised parton
distributions for non-strange sea quarks, seen through the violation of the Gottfried sumrule.
Since the 90’s he focused on high precision experiments of the spin structure of
the nucleon. He was co-author of the first experimental test (SMC) of the Bjorken sum
rule and of the results on the gluon polarisation in the nucleon (COMPASS) measured
independently in the production of open charm and in the high-pt hadron pair production.
Jan Nassalski’s group from the So̷ltan Institute for Nuclear Studies also successfully
contributed to the NA48 experiment at CERN dedicated to studies of the CP violation
in decays of K 0 mesons.
Jan’s scientific output consists of about 200 publications in international scientific journals
and of numerous conference presentations. In 2005 professor Nassalski was awarded
in Poland with Golden Order of Merit.
He was a devoted guide of younger colleagues in their scientific growth. In Poland
he was tireless in outreach activities popularizing science and was publishing widely in
Polish media. He gave interviews to journalists and helped them to reach interesting
places and information. He participated in conferences for school students and teachers
and supported the organization of such events. The educational exhibition on the LHC,
circulating in Poland, was created with his essential contribution. He played a vital role
in making the CERN’s high school teacher program a great success in Poland. He was
particularly proud of this work, and justifiably so.
Those people who met him could agree that he was a man of great integrity, rigorous
in thinking and clear communicator. Although softly spoken, he knew how to carry
an argument. Polite and with a natural kindness and sense of humour he was a true
gentleman. Physics was his great passion, but not the only one. He was fond of various
outdoor activities in the country, at the forests or in the mountains.
We will remember Him as as an excellent physicist and a good friend.
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