Experiments towards optical nuclear spectroscopy with thorium-229 [Elektronische Ressource] / Kai Zimmermann

Experiments TowardsOptical Nuclear SpectroscopyWith Thorium-229Von der Fakult¨at fu¨r Mathematik und Physik derGottfried Wilhelm Leibniz Universit¨at Hannoverzur Erlangung des GradesDoktor der NaturwissenschaftenDr. rer. nat.genehmigte DissertationvonDipl.-Phys. Kai Zimmermanngeboren am 25. Dezember 1976 in Berlin2010Referent: PD Dr. Ekkehard PeikKorreferent: Prof. Dr. Ernst RaselTag der Promotion: 10.06.2010Abstract229Thediscoveryofthelow-lyingisomericnuclearstateof That7.6±0.5eVabovethe ground state opened a new field of research as a bridge between nuclear andatomicphysics. Sinceindirectγ-spectroscopytechniqueswereappliedfordetectionof the isomeric state, the direct observation of the nuclear photon emission is still229mpending. This thesis describes the steps towards the direct observation of Th.Thefirstconductedexperimentsexaminemeasurementsofatomsintheisomeric229m 233state Thbeingproducedintheα-decayof U.Recoilatomswereejectedfrom233a thin U source, accumulated in an absorber and analyzed for the emission ofUV and VUV photons. No evidence for the decay of the isomeric state was found.The observed background signal has been identified as Cherenkov radiation.The main part of this thesis describes the setup of a linear Paul trap with a high4 +storage capacity that has been built and loaded with more than 8?10 Th ionsusing laser ablation loading.