Helmut Paul was born in 1929 as child of Hans and Ilona Paul (née Just) in
Vienna. Both parents were of middle class origin. The father was employed in the accounting and financial sector of the
Siemens company, the mother worked first in the household and later as an interpreter in the American Embassy in Vienna. Helmut Paul was an excellent pupil, and it became soon apparent that he was gifted in mathematics. He received his secondary education (Gymnasium) partly in Berlin, partly in Gmunden, Upper Austria, and got his Matura (Abitur) in Vienna in 1947. Paul began the study of physics and mathematics at the
University of Vienna in the fall of 1947. Among his professors in mathematics were the world-renowned mathematicians
Johann Radon and
Edmund Hlawka; there were friendly private relations to Radon and his family. Among his professors in physics in Vienna were
Hans Thirring,
Felix Ehrenhaft and later the nuclear physicist
Berta Karlik. Paul spent the year 1950/51 with a fellowship from the
US State Department at the Graduate School of
Purdue University in
Lafayette, USA. After returning to Vienna, Paul obtained a half time position at the
Institute for Radium Research, Vienna, of the
Austrian Academy of Sciences, which was directed by Professor Karlik. This employment was of great significance for Paul privately as well: He met the secretary of Professor Karlik, Maria Elisabeth Mathis (1931 - 2008), and fell in love with her. After two very fruitful years in Geneva, Paul went a third time to Purdue, this time as a visiting professor, supplying for Professor Steffen. There he studied a beta-gamma angular correlation. In the meantime, a new nuclear research center was established in
Seibersdorf near Vienna, where close colleagues from the
Radium Institute (Rupert Patzelt) and the 2nd Physics Institute of Vienna University (Peter Weinzierl) were active. Weinzierl offered him a position in Seibersdorf, und Paul accepted. An essential part of his work was devoted to the measurement of the electron-neutrino angular correlation in
neutron decay, a difficult project that went on for years and was finally concluded when Paul was no longer at Seibersdorf. In Brookhaven, Paul attempted to find a possible
parity admixture in an excited state of a radioactive
hafnium isotope, which would manifest itself by a small
circular polarization of the emitted
gamma radiation. The result was negative: there was no circular polarization. While at Brookhaven, Paul also published a summarizing article on the shapes of beta spectra which he had already begun at Seibersdorf. In 1970, Paul received a call to the young
University of Social Sciences, Economics and Business in
Linz (from 1975: Johannes Kepler University of Linz) for the newly established chair of Experimental Physics. Paul had the chance to cooperate in the planning of his professorship even prior to beginning his office. Since no chair for experimental physics had existed before, everything had to be built up from scratch (teaching, laboratories, electronics, mechanical workshop). Paul started his professorship on 1 April 1971. Soon an electrostatic
particle accelerator for 700 keV protons was installed (later also a
tandem accelerator), und in collaboration with O. Benka, D. Semrad, A. Kropf and others, atomic physics experiments were started. To make the Linz group internationally known, Paul started to organize international workshops: at first three on theories of
ionisation of inner
atomic shells. A table of cross sections for K shell ionisation by light ions, established together with J. Muhr and O. Bolik, resp., is available in the Internet. Later, Paul's interests turned toward the
stopping power of matter for charged particles, a subject on which D. Semrad, P. Bauer, R. Golser and other coworkers had already worked intensively for some time. He initiated again three international workshops on this theme. In Juli 1995, Paul's group initiated the Sixteenth International Conference on Atomic Collisions in Solids in Linz, with Paul as Chairman; D. Semrad, P. Bauer and O. Benka were editors of the conference volume. The years in Linz were a very successful time for Paul. Apart from teaching and research, Paul's managing qualities were appreciated and asked for. Paul's equilibrated and confidence-inspiring personality He was co-author of several reports of the
International Commission on Radiation Units and Measurements (ICRU) and of a report of the
International Atomic Energy Agency. Even after his retirement from active university duty in 1996, Paul received invitations to specialized conferences abroad, notably to the USA (last time 2012), but also to Brazil (2011). In 1990, Paul began to establish a collection of all published Stopping Power Data for light
Ions, with many graphical displays, and to install it in the Internet. In the meantime he has extended this collection to all positive ions, and he kept it updated till his death. It was important to him to compare these data statistically with various theories, in order to judge the quality of the data (and of the theories). His private interests included extended travels, the participation in a church choir and work on the genealogy of his family. == Selected publications ==