Jan Nassalski 1944–2009
Jan Nassalski, a prominent figure in the deep inelastic scattering community, an ingenuous physicist and a dedicated teacher, passed away on 5 August.
Jan graduated from the physics department of Warsaw University in 1966. He started his scientific career at Warsaw University of Technology and in 1971 he joined the Institute of Nuclear Research (now the Soltan Institute for Nuclear Studies), where he later became scientific director. His research work centred on the physics of elementary particles of matter and their interactions and he collaborated with the Laboratory of High Energy Physics at JINR, the Rutherford Laboratory in the UK, and Fermilab. From the late 1970s, however, his research was concentrated at CERN.
His continuous participation in one of CERN's longest running experimental facilities started when he joined the European Muon Collaboration and in the early 1980s he set up a group in Warsaw to study the nucleon structure in deep inelastic muon scattering. He participated in the ground-breaking discovery in 1988 that the quark spins contribute little to the nucleon spin and he was a key contributor to the structure-function studies in the New Muon Collaboration, leading to the measurement that showed violation of the Gottfried sum rule.
In the 1990s Jan focused on high-precision experiments of the polarized structure of the nucleon. Under his leadership the Warsaw group contributed to the first test of the Bjorken sum rule by the Spin Muon Collaboration and he was essential in studies of gluon polarization in the nucleon by the COMPASS experiment – an important step in understanding the quark/gluon structure of matter. For his colleagues Jan was the reference point for all aspects of physics in the domain of deep inelastic scattering.
Jan's group from the Soltan Institute made successful contributions to the NA48 experiment at CERN, with read-out electronics for the liquid krypton calorimeter. The group was also active in physics analysis, leading some studies of rare kaon decays and precise measurements of fundamental properties of neutral mesons. In particular, Jan was one of the main authors of the precision measurement of the mass of the η.
In addition to his research, Jan was chair of the Programme Advisory Commission for High Energy Physics of the Scientific Council of JINR and he was a member of the Scientific Council at DESY. He also chaired the High Energy Physics Commission at the Polish Atomic Energy Council.
In his home country, Jan was tireless in his outreach activities, publishing widely in the Polish media. Whenever CERN launched a new outreach initiative, the uptake in Poland was phenomenal, and Jan's hand could be seen behind the success. For example, a CERN educational CD was distributed free with a popular science magazine, and more recently, Jan played a vital role in making CERN's high-school teacher programme a great success in Poland. He was particularly proud of this work and justifiably so.
Jan was a delegate to CERN Council from December 2004, representing his country's interests powerfully and with great conviction. Although softly spoken, he knew how to carry an argument. Yet even in the most heated of debates, he was a model of politeness and courtesy.
Thanks to his natural kindness and sense of humour, his infinite patience and above all his extreme rigour and great integrity, exchanges with Jan were of a high standard and rewarding. The quality and accuracy of his judgments always made them an irreplaceable reference. Particle physics has lost not only an excellent physicist, but also a true gentleman.
Jan was to all of us more than a colleague. We will greatly miss his perceptiveness and sensitivity as well as his advice, and remember him as a precious friend.
His colleagues and friends.