Rostock 2019 – scientific programme

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A: Fachverband Atomphysik

A 6: Precision Spectroscopy of atoms and ions II (joint session A/Q)

A 6.5: Talk

Monday, March 11, 2019, 15:15–15:30, S HS 2 Physik

Determination of the electron affinity of astatine for IS615 — •David Leimbach — CERN, Geneva, Switzerland — Institut für Physik, Johannes Gutenberg-Universität, Mainz, Germany — Department of Physics, University of Gothenburg, Gothenburg, Sweden

Astatine is a purely radioactive and the rarest naturally occurring element on earth, exhibiting a number of short lived alpha emitting isotopes. E.g. one of the longer lived isotopes, 211At, is of special interest as an agent for targeted alpha therapy (TAT), a method of treating cancer directly at the location of a tumor with alpha emitting particles. On the other hand, the fundamental quantity of the electron affinity (EA) of astatine is not known. Together with the just recently measured first ionization potential (IP) this value is of importance to determine the unknown electronegativity of this element which could give valuable benchmarks for quantum chemical calculations predicting the chemical properties of this element and its compounds. In order determine the EA of radioisotopes via laser photodetachment, the Gothenburg Anion Detector for Affinity measurements by Laser PHotodetachment (GANDALPH) was built. Following the first ever measurement of the EA of a radiogenic isotope in 2016 [4], GANDALPH has recently received multiple upgrades to facilitate beam tuning and detection of low intensity (<1pA) ion beams. During an experimental campaign at CERN-ISOLDE in 2018, the GANDALPH beamline was used to successfully measure the EA of astatine. Experiment and results of these measurements will be presented and compared to expectations and recent theoretical calculations.