Manifestations Scientifiques

Laser Isotope Separation revisited – radioisotope purification by resonance ionization mass spectrometry at Mainz University

by Prof. Klaus Wendt

Europe/Paris
Description

Aside of the on-going development of on-line laser ion sources world-wide, resonance ionization mass spectrometry (RIMS) has demonstrated its great versatility in the field of radioisotope separation and ion beam purification. This is based on the suitability and reliability of state-of-the-art solid state laser systems, which were specifically developed and adapted for this task. The application primarily profits from the universality of the RIMS technique, the high overall efficiency of the ionization process and the unrivaled suppression of isobaric and other background in the final badge. For complete elimination of isobaric interferences and disturbances from neighboring isotopes specific techniques of ion source operation or ion-beam gating are presently developed e.g. at the on-line facitilies ISOLDE.
The RISIKO laser mass separator at Mainz University is used as ion source development set-up and off-line radioactive ion beam facility. Permanently ongoing are laser spectroscopic activities in atomic spectra of e.g lanthanides, actinides or other purely radioactive elements. These studies are the basic prerequisite for the application at on-line radioisotope production plants, in laser-based ultratrace analysis of radiotoxic contaminations or for preparation of the generation of nuclear-medical species, e.g., at CERN-Medicis [1]. On top of that a number of applications in isotope purification for fundamental and applied research are carried out In the field of long-lived radioisotopes, which are accessible at RISIKO.
One example of specific radioisotope purification concerns the isotope 163-Ho and its efficient implantation into the magnetic metallic calorimeter chips of the ECHo project for determination of the neutrino mass [2]. Purification of the isotope 53-Mn, delivered from beam dump recovery as part of the Meancorn project of PSI [3], is carried out for supporting lifetime measurements of this extremely long-lived isotope. A further activity concerns a radiometrical clean implantation of the isotope 225-Ra as standard for the PTB.
Advances and limitations of the RIMS technique in respect to this specific application and concerning the spectroscopic background, the laser and ion source design and optimization will be discussed.
[1] R. M. dos Santos Augusto et al., CERN MEDICIS – A New Facility, Appl. Sci. 4, 265-281 (2014)
[2] L. Gastaldo et al., The electron capture in 163Ho experiment – ECHo, Eur. Phys. J. Special Topics 226, 1623–1694 (2017)
[3] R. Dressler et al., MeaNCoRN – Measurement of Neutron capture cross sections and deter- mination of half-lives of short-lived Cosmogenic Radio-Nuclides, https://www.psi.ch/lrc/meancorn