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 30kV 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 finite element method (FEM) thermal-electric calculations and chemical equilibrium simulation using the Gibbs energy minimization method. The new setup provides a much improved selectivity in laser ionization versus interfering surface ionization of 2700(500) and a superior overall efficiency of 41(5) \, \textrm{%} for the ion-implantation process.
@article{arxiv.1809.01358,
title = {Optimization of a laser ion source for $^{163}$Ho isotope separation},
author = {Tom Kieck and Sebastian Biebricher and Christoph E. Düllmann and Klaus Wendt},
journal= {arXiv preprint arXiv:1809.01358},
year = {2019}
}