Bonn 2020 – wissenschaftliches Programm

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HK: Fachverband Physik der Hadronen und Kerne

HK 1: Invited Talks I

HK 1.1: Preisträgervortrag

Montag, 30. März 2020, 11:15–11:45, H-HS X

50 Years of Online Optical Spectroscopy and Mass Spectrometry — •H.-Jürgen Kluge — GSI, Darmstadt — University of Heidelberg — Laureate of the Robert Wichard Pohl Prize 2020

Inspired by the observation of the parity violation in the fifties of the last century, Ernst Otten proposed and performed in 1970 at ISOLDE/CERN the very first online optical spectroscopy of short-lived isotopes at an accelerator facility. Neutron-deficient mercury isotopes were polarized by optical pumping by use of a spectral lamp. Its circular-polarized light was made tunable via the Zeeman effect by applying a magnetic field to the Hg discharge lamp. The resulting beta-asymmetry allowed to determine spin, moments, shape, and size. This led to the first observation of nuclear shape coexistence.

Before 1985, the binding energies or masses of radionuclides had been determined via observation of nuclear decays or reactions with often rather large uncertainties and were sometimes simply wrong. In 1985, ISOLTRAP was installed at ISOLDE, the very first online Penning trap facility for determining the masses of short-lived isotopes. Since then the atomic masses of over 400 radionuclides could be determined by ISOLTRAP with a relative uncertainty of 10-7 or better.

With the invention of tunable lasers by T. Hänsch in 1971 and the further development of ion traps, lasers, and spectroscopic methods, these atomic-physics methods have become workhorses for investigating nuclear ground state properties far from stability at accelerators world-wide.