Helmut Paul

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Helmut Paul (2014)

Helmut Paul (born November 4, 1929 in Vienna , † December 21, 2015 in Linz ) was an Austrian nuclear and atomic physicist . As a full professor of experimental physics, he taught at the University of Linz from 1971 until his retirement in 1996. He was rector of the university from 1974 to 1977.

Life

Helmut Paul was born in Vienna in 1929 as the only child of Hans and Ilona Paul (née Just). Both parents came from a middle-class background. The father worked in the accounting and finance department of Siemens, the mother was initially a housewife and later an interpreter at the American embassy in Vienna.

Helmut Paul was a very good student, and it became clear early on that he was gifted with mathematics. The high school years, partly in Berlin, partly in Gmunden, ended in Vienna with the Matura in 1947. Paul began studying physics and mathematics at the University of Vienna in autumn 1947 . His math teachers included the world-famous mathematicians Johann Radon and Edmund Hlawka ; there were also friendly relations with Radon and his family. His physics teachers in Vienna included Hans Thirring , Felix Ehrenhaft and later the nuclear physicist Berta Karlik .

Paul spent the academic year 1950/51 on a scholarship from the US State Department at the Graduate School of Purdue University in Lafayette , USA. Paul wrote a master's thesis on the probability of Geiger counters responding to gamma radiation and was able to complete this academic year with a Master of Science degree. The supervisor of this thesis, Professor Rolf M. Steffen, informed Paul that he would like to supervise him as a doctoral student.

In the spring of 1952 Paul was back at Purdue University, this time for his doctorate (Ph.D.), which he completed in December 1954 with a thesis on the weakening of the gamma-gamma angle correlation in the radioactive decay of the atomic nucleus of a hafnium Isotopes due to the time-varying fields in liquid solutions, depending on the temperature. After returning to Vienna, Paul was given a part-time position at the Institute for Radium Research at the Academy of Sciences , which was headed by Professor Karlik. This position was also very important for Helmut Paul personally. He got to know and love Professor Karlik's secretary, Maria Elisabeth Mathis. Helmut Paul and Elisabeth Mathis got engaged in December 1956, and the wedding took place in June 1957. The marriage produced three children.

In October 1957, Helmut Paul took up a Ford Foundation scholarship at CERN in Geneva , which Berta Karlik had given him. At CERN, the first particle accelerator, the synchrocyclotron , had just gone into operation, and Paul was able to participate in the first experiment that was carried out with this device. It was about the search for the rare decay of the charged pion into an electron and a neutrino ; the decay was detected with a probability of 0.012% relative to the normal decay in muon and neutrino.

After two very fruitful years in Geneva, Paul went to Purdue a third time, this time as a visiting professor on behalf of Professor Steffen. There he studied a beta-gamma angle correlation. In the meantime, a new research center in Seibersdorf near Vienna has been set up in Austria, at which close specialist colleagues from the Radium Institute (Rupert Patzelt) and the 2nd Physics Institute of the University of Vienna (Peter Weinzierl) worked; Weinzierl offered him a position in Seibersdorf, and Paul accepted. Paul worked at the Seibersdorfer Zentrum from October 1960 to March 1971, interrupted by a fourth stay in America, this time at the Brookhaven National Laboratory on Long Island (1965/66).

In Seibersdorf, Paul had a magnetic interimage beta spectrometer available. With this he measured the shapes of beta spectra . But most of all, he examined the spectrometer itself to show that the shapes measured were not caused by errors in the instrument. A major part of his work was a project to measure the angular correlation in the beta decay of the neutron , a difficult project that dragged on for years and was finally ended when Paul was no longer in Seibersdorf.

In Brookhaven Paul tried to detect a possible mixture of parities in an excited state of the radioactive atomic nucleus of a hafnium isotope, which would be expressed in a small circular polarization of the emitted gamma radiation. The result was negative: no circular polarization was found. In addition, Paul published a comprehensive work on the forms of beta spectra, which he had already started in Seibersdorf.

In 1970 Paul received a call to the young university for social and economic sciences (from 1975: Johannes Kepler University) Linz for the newly established full professorship for experimental physics. Paul had the chance to participate in the planning for the furnishing of the newly constructed physics building before he took up his professorship. Since there had not yet been an experimental chair, everything (teaching, workshop, electronics, etc.) had to be rebuilt.

He took up his professorship on April 1, 1971. Soon a particle accelerator for 700 keV protons was purchased (later also a tandem accelerator ), and atomic physics experiments were carried out in collaboration with O. Benka, D. Semrad, A. Kropf and others. In order to make the Linz group internationally known, workshops were organized on Paul's initiative, initially three on the ionization of inner atomic shells using light ions. A table of the cross sections for K-shell ionization by light ions created by Paul and J. Muhr and O. Bolik is available on the Internet.

After Paul's interest had turned to the braking power of charged particles in matter (stopping power), he again initiated three international workshops on this topic, which D. Semrad, P. Bauer, R. Golser and other employees had been intensively concerned with for a long time.

In July 1995 the “Sixteenth International Conference on Atomic Collisions in Solids” took place in Linz, with Paul as Chairman; D. Semrad, P. Bauer, O. Benka acted as editors of the conference proceedings.

The years in Linz were a very successful time for Paul. In addition to teaching and research, Paul's management skills were also valued and in demand. Paul's even-tempered and trustworthy personality contributed to Paul becoming a Senator in 1972. In 1973 he was elected dean of the natural science and technology faculty, and in 1974 he was elected rector of the university - for three years until 1977. In 1985 he was re-elected dean for two years.

After his retirement in 1996, Paul's interest also turned to medical-physics topics. He co-authored several reports from the International Commission on Radiation Units and Measurements (ICRU) and a report from the International Atomic Energy Agency . Even after his retirement in 1996, Paul received invitations to give lectures at specialist conferences abroad, particularly in the USA (most recently in 2012), but also to Brazil (2011).

In 1990 Paul began to build up a collection of all published brake loss data for light ions , with numerous graphical representations, and to put it on the Internet. He extended the collection to include all positive ions and kept it up to date until his death. It was important to him to statistically compare these data with different theories in order to be able to assess the quality of the data (and the theories). His private interests included traveling extensively, participating in a church choir, and working on a family genealogy.

Works (selection)

Web links

Individual references, comments

  1. a b c d e Mitio Inokuti: Helmut Paul, a happy physicist , Nuclear Instruments and Methods B 115 (1996) xiii
  2. a b c d Helmut Paul: My Life as a physicist September 22, 1998, added August 12, 2006 and August 16, 2013, accessed May 2, 2017.
  3. T. Fazzini, G. Fidecaro, AW Merrison, H. Paul, AV Tollestrup: Electron Decay of the Pion , Physical Review Letters 1 (1958) 247. doi : 10.1103 / PhysRevLett.1.247
  4. J. Ashkin, T. Fazzini, G. Fidecaro, AW Merrison, H. Paul, AV Tollestrup: The Electron Decay Mode of the Pion , Il Nuovo Cimento Ser. X, 13 (1959) 1240
  5. Helmut Paul: Beta-Gamma Directional Correlations in the Decay Sb 124 → Te 124 , Physical Review 121 (1961) 1175
  6. ^ H. Paul: Instrumental distortion of beta spectra measured in an intermediate-image spectrometer , Nucl. Instrum. Methods 37 (1965) 109
  7. R. Dobrozemsky, E. Kerschbaum, G. Moraw, H. Paul, C. Stratowa, P. Weinzierlberg, Electron-neutrino angular correlation coefficient a Measured from free-neutron decay , Physical Review E 11 (1975) 510. doi : 10.1103 / PhysRevD.11.510
  8. The ASTRA reactor in Seibersdorf
  9. ^ Helmut Paul: Shapes of Beta Spectra , Nuclear Data A2 (1967) 281
  10. ^ Proc. Workshop on Theories of Inner Shell Ionization by Heavy Particles, Nucl. Instr. and Meth., Linz, Austria, May 17-19, 1979, 169 (1980), p. 249
  11. ^ Proc. Second Workshop on Inner Shell Ionization by Light Ions, Nucl. Instr. and Meth., Linz, Austria, March 12-14, 1982, 192 (1982), p. 1
  12. ^ Proc. Third Workshop on Inner Shell Ionization by Light Ions, Nucl. Instr. and Meth., Linz, Austria, August 4-5, 1983, 232 (1984), p. 211
  13. ^ Cross Sections for K-Shell Ionization by Light Ions
  14. ^ Proc. Workshop on Stopping Power for Low Energy Ions, Linz. Austria. September 20-21, 1984, Nucl. Instr. and Meth. B 12 (1985)
  15. ^ Proc. Second Workshop on Stopping Power for Low Energy Ions, Linz, Austria, September 18-19. 1986. Nucl. Instr. and Meth. B 27 (1987) 249
  16. ^ Proc. Gmunden Workshop on Aggregation and Chemical Effects in Stopping, Nucl. Instr. and Meth. B 93 (1994)
  17. ^ Sixteenth International Conference on Atomic Collisions in Solids , Nucl. Instr. Methods 115 (1996) Issues 1-4, Pages 1-608
  18. Paul H., Jäkel O., Geithner O .: The influence of Stopping Powers upon Dosimetry for Radiation Therapy with Energetic Ions , Advances in Quantum Chemistry (2007) Vol. 52, pp. 289-306
  19. ^ H. Paul: On the Accuracy of Stopping Power Codes and Ion Ranges Used for Hadron Therapy , in: Dzevad Belkic (Ed.): Theory of Heavy Ion Collision Physics in Hadron Therapy, Adv.Quantum Chem., Vol. 65 (2013 ), pp. 39-59, Elsevier / Academic Press
  20. Stopping of Ions heavier than Helium , ICRU Report 73, Journal of the ICRU (2005)
  21. M. Berger, H. Paul: Stopping powers, ranges and straggling , Chapter 7 of "Atomic and molecular data for radiotherapy and radiation research", IAEA-TECDOC-799 (1995)
  22. Stopping Power for Light Ions: Graphs, Data, Comments and Programs
  23. Helmut Paul: Comparing experimental stopping power data for positive ions with stopping tables, using statistical analysis , Nucl. Instr. Methods B 273 (2012) 15
  24. Helmut Paul's Genealogy ( Memento of the original from December 22, 2015 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. @1@ 2Template: Webachiv / IABot / andreas_paul.public1.linz.at