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{{Short description|Physicist in exp. nuclear physics}}
{{Draft topics|biography|physics}}
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[[File:Bild-HG-Foto-Hirch-2023.jpg|thumb|Photo of Hans Geissel]]
[[File:Bild-HG-Foto-Hirch-2023.jpg|thumb|Photo of Hans Geissel]]

Revision as of 11:15, 6 December 2023

Photo of Hans Geissel

Hans Geissel (born May 13, 1950 in Alsfeld) is a German experimental physicist who studies the atomic and nuclear interaction of energetic heavy ions with matter. In particular, his research focuses on the discovery of new isotopes and the investigation of their properties. Geissel was an adjunct professor at the II Institute of Physics at JLU Giessen (emeritus 2015)[1] and was head of the FRS / Super-FRS department at the GSI Helmholtz Centre for Heavy Ion Research in Darmstadt, where he is now a Helmholtz Professor.[2]

Biografy

Hans Geissel studied physics at the Justus Liebig University of Giessen in Gießen. In his diploma thesis, which was supervised by Prof. Dr. Gottfried Münzenberg, he worked on the development of time-of-flight detectors as part of the construction of the heavy-ion separator SHIP in the newly-founded research center GSI in Darmstadt. His doctoral thesis (supervisor: Prof. Dr. Peter Armbruster) concentrated on the study of atomic interactions and the slowing-down of heavy ions in matter in the energy range up to 10 MeV/u, which was available at the UNILAC for all projectiles up to uranium for the first time.

From 1982-1984, Hans Geissel worked as a post-doctoral student at the Canadian institute AECL in Chalk River (Ontario) in the field of solid-state physics. In the group of Prof. Dr. William Lennard, he carried out several experiments on a research reactor and smaller ion accelerators.

Construction of the fragment separator FRS at GSI

Back in Germany at GSI in 1984, his major research activity was the design, calculation and construction of the projectile fragment separator FRS with G. Münzenberg and the GSI infrastructure as part of the SIS-ESR project.[3]

Generation and investigation of new atomic nucleis

Geissel has performed outstanding research at GSI's FRS for over three decades, in particular on the production and investigation of new, unstable isotopes.[4] In 1999, GSI was awarded the 7th SUN-AMCO Medal of the IUPAP for its contributions to the production and mass determination of heavy nuclei, which Hans Geissel and Sigurd Hofmann accepted on behalf of the research center.[5] Since 2012, Hans Geissel has held the world record with the discovery of more than 280 new isotopes.[6]

The first proton-halo nucleus and 2-proton radioactivity are examples of important discoveries made with the FRS and its detector systems. New heavy neutron-rich isotopes are of great importance for the detailed understanding of the element synthesis in stars. With the FRS branch in combination with the storage and cooler ring ESR, several hundred new ground-state masses were measured for the first time and the new β−-decay mode into bound atomic states was investigated. Pioneering experiments with the FRS-ESR combination were led by Hans Geissel for more than ten years. The third FRS branch provides relativistic exotic projectile beams to the large detector systems LAND and ALADIN, where new nuclear properties have been discovered by applying full kinematic measurements of all nuclear reaction products.

Since the FRS is also a high-resolution magnetic spectrometer, it has been used to investigate new properties in the field of atomic collisions of relativistic heavy ions. These studies are directly related to the new results of Hans Geissel’s doctoral thesis and the AECL experiments in the low-energy range. The experimental results at relativistic velocities clearly show strong deviations from the widely-used Bethe theory.[7] Precise data on atomic interactions are also required for tumor therapy with ions and other applications. In the early 1990s, Hans Geissel was also strongly involved in the development of positron-emitting beams for the irradiation of tumor patients. An important milestone in Hans Geissel's scientific work was the experimental discovery of deeply-bound pionic states in heavy atoms (Pb, Sn). Hans Geissel and his colleagues in international research teams in France, Japan, Canada and the USA have contributed to an improved understanding of both the atomic and nuclear interaction of energetic ions with matter. The successful experiments with the FRS will be extended to higher rates and accuracies in the near future with the Super-FRS[8] currently under construction.

Work in Education

Since 1985, Hans Geissel has supervised many generations of diploma, master and doctoral students, most of which were carried out at the Justus-Liebig University in Giessen. He habilitated in 1994 in the physics department at his alma mater in the 2nd Physics Institute (headed by Prof. Dr. Volker Metag at the time) and has since been part of the IONAS Group, which was founded in 2000. In keeping with his spirit, cutting-edge research using large-scale experimental equipment and the training of students are inseparable.

Awards

References

  1. ^ "II. Physikalisches Institut: AG Scheidenberger". uni-giessen.de. Retrieved 2023-08-12.
  2. ^ a b "Website of the FRS-Group". gsi.de. Retrieved 2023-08-12.
  3. ^ H. Geissel, P. Armbruster, K. H. Behr et al.: The GSI projectile fragment separator (FRS): a versatile magnetic system for relativistic heavy ions. In: Nuclear Instruments & Methods in Physics Research B 70(1-4), S. 286–297 (1992). doi:10.1016/0168-583X(92)95944-M
  4. ^ H.Geissel, Gottfried Münzenberg, K. Riisager: Secondary Exotic Nuclear Beams. In: Annual Review of Nuclear and Particle Science 45(1), S. 163–203 (1995). doi:10.1146/annurev.ns.45.120195.001115
  5. ^ "Report to the 1999 General Assembly for 1996-99". iupap.org. C2. Commission on Symbols, Units, Nomenclature, Atomic Masses and Fundamental Constants (SUNAMCO). Retrieved 2023-11-18.
  6. ^ He is the researcher with the most co-authorships in articles that detect a new isotope, with 277 co-authorships/isotopes as of 2022. See Michael Thoennessen. "Top 1000 (co)authors 2022" (PDF). Retrieved 2023-08-12. In 2012, he topped the list for the first time[1] with 272 co-authorships. For the criteria used, see Discovery of Nuclides Project.
  7. ^ H. Geissel, H. Weick, C. Scheidenberger et al.: Experimental studies of heavy-ion slowing down in matter. In: Nuclear Instruments & Methods Physics Research B 195, S. 3–54 (2002). doi:10.1016/S0168-583X(02)01311-3
  8. ^ H.Geissel, H. Weick, M. Winkler et al.: The Super-FRS project at GSI. In: Nuclear Instruments & Methods in Physics Research B 204, S. 71–85 (2003). doi:10.1016/S0168-583X(02)01893-1
  9. ^ "Membership Awards". gsi.de. Retrieved 2023-11-06.
  10. ^ Justus-Liebig-University Giessen (2010-07-28). "Ehrendoktor für Prof. Dr. Hans Geissel". Retrieved 2023-06-30.
  11. ^ Michael Thoennessen (2012). "Table of top 1000 (co)authors". Retrieved 2023-08-12.
  12. ^ "Auszeichnung der Foundation for Polish Science for Prof. Hans Geissel". idw. Justus-Liebig-Universität Gießen. 2020-02-09. Retrieved 2023-06-30.
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