Th-234: Lise Meitner and Internal Conversion and Otto Hahn – Nuclear Isomerism and the role of isomeric nuclei in nuclear condensed matter physics

Dr. Mahnke Heinz-Eberhard

email: mahnke@helmholtz-berlin.de ,    

webpage: https://www.helmholtz-berlin.de/pubbin/vkart.pl?v=ozx;sprache=en

Abstract:

More than hundred years ago, Lise Meitner and Otto Hahn intensively studied the decay of Th-234, working in close cooperation. While Otto Hahn discovered nuclear isomerism, Lise Meitner studied electrons closely related to the gamma transitions following the transformation of Th into Pa. Both, nuclear isomerism and the internal conversion process, had strong impact in the use of nuclear isomers in the so-called nuclear condensed matter physics.

Thirty years later, with their successful application of nuclear magnetic resonance NMR to investigate the structure of atoms in liquids and solids, Felix Bloch and Edward Mills Purcell (Nobel prize 1952) opened new ways to study local aspects in solids via the hyperfine interaction of a nuclear moment with extra-nuclear fields. While for roughly half the elements no appropriate nuclei are available because of either spin-zero or spin-1/2 nuclei, respectively, one finds nuclei in isomeric states with spins suitable not only for magnetic dipole but also for electric quadrupole interaction almost over the whole periodic table. The development of adequate techniques to study hyperfine interactions like Mössbauer spectroscopy, Perturbed Angular Distribution and/or Correlation, and radiation-detected-NMR adapted to the various half-lives of the isomers lead to the field of nuclear solid-state physics. Due to its very nature, the restricted range of the hyperfine interaction in combination with the high sensitivity for detecting nuclear radiation, materials studies using isomers are ideal to investigate local structures on highly isolated atoms in solids with extremely low concentrations.

Among the key words for topics in solid-state physics are fullerenes (e.g. F-19), point defects in metals and insulators (e.g. Cd-111 and Sn-119), charged defect centers in semiconductors (e.g. Cd-111), local magnetic moments (e.g. Fe-54), surface structures using conversion electron Mössbauer spectroscopy (e.g. Fe-57), where the study of the hyperfine interaction of isomeric nuclei greatly contributed to an improved understanding. In return, the advanced understanding of extra-nuclear fields in solids resulted in reliably determining nuclear moments by measuring the hyperfine interaction, thus contributing to key issues in nuclear structure like high-spin isomers (in e.g. Gd-147, Rn-211 and Rn-212).

Bio:

Dr Mahnke is honorary professor of the Physics Department at Freie Universität Berlin. He was a senior scientist at HZB (Helmholtz-Center Berlin for materials and energy) and visiting professor at C2RMF (Centre de recherche et de restauration des Musées de France) of the Palais du Louvre in Paris (until 9/2009).

Starting with basic research in nuclear physics and solid state physics using nuclear techniques (especially in connection with ion beams) he moved into interdisciplinary research on our cultural heritage using ions and x-rays from synchrotron sources applied e.g. to the investigation of stained glass.

His recent interest is to virtually unfold / unroll papyri by tomographic techniques to get access to the hidden texts. His activities focus on the promotion of interdisciplinary research on cultural heritage, best manifested by his successful incorporation of this field into the highly prestigious conference Gordon Research Conference organized by the GRC, with the first conference successfully held in 2012, running biennially since then. He was the physics partner in the ERC starting grant “ELEPHANTINE – Localizing 4000 years of cultural history. Texts and scripts from Elephantine island in Egypt” (PI V. Lepper) from 2015 to 2022. He presently is a fellow of the Einstein Center Chronoi (Project “Folded Time – Ink in Time”). Heinz-Eberhard Mahnke initiated the new theatre play KERNFRAGEN – Gedenken an Lise Meitner (Core Issues – in memoriam Lise Meitner) and organized and coordinated the open lecture series on Lise Meitner at the FU Berlin during the winter semester 2018/19.

Affiliations

(1) Ägyptisches Museum und Papyrussammlung SMB SPK – Fellow Einstein Center Chronoi (Project “Folded Time – Ink in Time”)

(2) Freie Universität Berlin, FB Physik, Arnimallee 14, D-14195 Berlin,

(3) Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, D-14109 Berlin,