Laser photodetachment of radioactive 128I−. (31st August 2017)

• Record Type: Journal Article
• Authors: Rothe, Sebastian; Sundberg, Julia; Welander, Jakob; Chrysalidis, Katerina; Goodacre, Thomas Day; Fedosseev, Valentin; Fiotakis, Spyridon; Forstner, Oliver; Heinke, Reinhard; Johnston, Karl; Kron, Tobias; Köster, Ulli; Liu, Yuan; Marsh, Bruce; Ringvall-Moberg, Annie; Rossel, Ralf Erik; Seiffert, Christoph; Studer, Dominik; Wendt, Klaus; Hanstorp, Dag
• Is Part Of: Journal of physics. Volume 44:Number 10(2017:Oct.)
• Publication Date: 2017-08-31
• Subjects: ISOLDE -- electron affinity -- iodine -- photodetachment; Nuclear physics -- Periodicals; Particles (Nuclear physics) -- Periodicals; Physique nucléaire -- Périodiques; Particules (Physique nucléaire) -- Périodiques; Kernfysica; Elementaire deeltjes; 539.7
• DOI: 10.1088/1361-6471/aa80aa
• Languages: English
• ISSNs: 0954-3899

Abstract

Abstract: The first experimental investigation of the electron affinity (EA) of a radioactive isotope has been conducted at the CERN-ISOLDE radioactive ion beam facility. The EA of the radioactive iodine isotope 128 I ( t 1/2 = 25 min) was determined to be 3.059 052(38) eV. The experiment was conducted using the newly developed Gothenburg ANion Detector for Affinity measurements by Laser PHotodetachment (GANDALPH) apparatus, connected to a CERN-ISOLDE experimental beamline. 128 I was produced in fission induced by 1.4 GeV protons striking a thorium/tantalum foil target and then extracted as singly charged negative ions at a beam energy of 20 keV. Laser photodetachment of the fast ion beam was performed in a collinear geometry inside the GANDALPH chamber. Neutral atoms produced in the photodetachment process were detected by allowing them to impinge on a glass surface, creating secondary electrons which were then detected using a channel electron multiplier. The photon energy of the laser was tuned across the threshold of the photodetachment process and the detachment threshold data were fitted to a Wigner law function in order to extract the EA. This first successful demonstration of photodetachment at an isotope separator on line facility opens up the opportunity for future studies of the fundamental properties of negatively charged radioactive isotopes such as the EA of astatine and polonium.