Optimization of a laser ion source for 163Ho isotope separation

To measure the mass of the electron neutrino, the "Electron Capture in Holmium-163" (ECHo) collaboration aims at calorimetrically measuring the spectrum following electron capture in ¹⁶³Ho. The success of the ECHo experiment depends critically on the radiochemical purity of the ¹⁶³Ho sample, which is ion-implanted into the calorimeters. For this, a 30 kV high transmission magnetic mass separator equipped with a resonance ionization laser ion source is used. To meet the ECHo requirements, the ion source unit was optimized with respect to its thermal characteristics and material composition by means of the finite element method thermal-electric calculations and chemical equilibrium simulation using the Gibbs energy minimization method. The new setup provides an improved selectivity of laser ionization vs interfering surface ionization of 2700(500) and an overall efficiency of 41(5)% for the ion-implantation process.

Production and separation of 163Ho for nuclear physics experiments

This paper describes the production and chemical separation of the ¹⁶³Ho isotope that will be used in several nuclear physics experiments aiming at measuring the neutrino mass as well as the neutron cross section of the ¹⁶³Ho isotope. For this purpose, several batches of enriched ¹⁶²Er have been irradiated at the Institut Laue-Langevin high flux reactor to finally produce 6 mg or 100 MBq of the desired ¹⁶³Ho isotope. A portion of the Er/Ho mixture is then subjected to a sophisticated chemical separation involving ion exchange chromatography to isolate the Ho product from the Er target material. Before irradiation, a thorough analysis of the impurity content was performed and its implication on the produced nuclide inventory will be discussed.