High efficiency laser resonance ionization of plutonium

Three-step resonance photoionization spectra of plutonium have been studied with Ti:Sapphire lasers for the development of efficient laser ionization schemes for ultra-trace analysis of Pu isotopes by resonance ionization mass spectrometry. We observed eighteen intermediate excited states of even parity in the energy range 35568–36701 $${\text {cm}}^{-1}$$ cm - 1 , thirteen of them have not been previously documented, and a larger number of high-lying excited states and autoionizing states of odd-parity between 48238 and 49510 $${\text {cm}}^{-1}$$ cm - 1 . Three-color, three-photon ionization schemes via six intermediate states were evaluated under similar ion source operating conditions. This led to a highly efficient three-step scheme with an overall ionization efficiency of $$51.1 \pm 1.3\%$$ 51.1 ± 1.3 % , which is an order of magnitude improvement over the previously reported ionization efficiency for Pu.

Recent developments in resonance ionization mass spectrometry for ultra-trace analysis of actinide elements

Resonance ionization mass spectrometry is an efficient tool to detect minute amounts of long-lived radio-isotopes in environmental samples. Applying resonant excitation and ionization with pulsed laser radiation within a hot cavity atomizer enables the sensitive detection and precise quantification of long-lived actinide isotopes. Due to the inherently element selective ionization process, this method ensures ultimate suppression of contaminations from other elements and molecules. The characterization of in-source resonance ionization of the actinide elements U, Th, Np, and Am using a compact quadrupole mass spectrometer (QMS) setup are discussed.

Production, isolation and characterization of radiochemically pure 163Ho samples for the ECHo-project

Several experiments on the study of the electron neutrino mass are based on high-statistics measurements of the energy spectrum following electron capture of the radionuclide 163Ho. They rely on the availability of large, radiochemically pure samples of 163Ho. Here, we describe the production, separation, characterization, and sample production within the Electron Capture in Holmium-163 (ECHo) project. 163Ho has been produced by thermal neutron activation of enriched, prepurified 162Er targets in the high flux reactor of the Institut Laue-Langevin, Grenoble, France, in irradiations lasting up to 54 days. Irradiated targets were chemically processed by means of extraction chromatography, which allowed separating the formed Ho from the 162Er target-material and from the main byproducts 170Tm and 171Tm, which are co-produced in GBq amounts. Decontamination factors of >500 for Er and of >105 for Tm and yields of 3.6·1016 and 1.2·1018 atoms of 163Ho were obtained, corresponding to a recovery yield of 95 % of Ho in the chemical separation. The Ho-fraction was characterized by means of γ-ray spectrometry, Inductively-Coupled-Plasma Mass Spectrometry (ICP-MS), Resonance Ionization Mass Spectrometry (RIMS) and Neutron Activation Analysis (NAA). In this process, the thermal neutron capture cross section of 163Ho was measured to σHo-163 to Ho-164m= (23±3) b and σHo-163 to Ho-164g= (156±9) b for the formation of the two isomers of 164Ho. Specific samples were produced for further purification by mass separation to isolate 163Ho from the Ho-isotope mixture, as needed for obtaining the energy spectrum within ECHo. The partial efficiency for this second separation step is (32±5) %.