Special Particle and Astroparticle Physics Seminar

Resonance ionization laser spectroscopy: from nuclear structure to a cure for cancer

Thomas Cocolios

KU Leuven

The use of resonance ionization for the production and purification of radioisotopes is regularly used for trace analysis [1] and has also been studied in the past for isotope enrichment [2]. At Isotope Separation On Line (ISOL) facilities, such as TRIUMF ISAC or CERN ISOLDE, this technique is used to selectively enhance the yields of a chosen element and sometimes even provides isomeric separation [3-4].

Beyond its power for production or separation, resonance ionization can also be used to study the hyperfine structure and isotope shifts of atomic transitions, contributing to searches for new physics in atoms and molecules [5], or the study of nuclear observables in a nuclear-model-free approach [6]. Different conditions have to be met in order to reach the required resolution, and CERN ISOLDE has a wide array of facilities to address these varying needs, between the Resonant Ionization Laser Ion Source (RILIS) and the Collinear Resonance Ionization Spectroscopy (CRIS) experiment.

Parasitically to CERN ISOLDE, a new facility called MEDICIS (MEDical Isotopes Collected from ISolde) has recently been started, which aims at producing radioisotopes for medical research [7]. Given that we have up to now identified >3,000 different radioisotopes, isn't it striking that only a handful are used for medical applications? One of the reasons for this situation is that without demand, there is no supply of new isotopes, while so long as those new isotopes are not available, no research can be made. By providing these isotopes “free of charge�” to research teams, CERN MEDICIS aims at breaking this conundrum and seeds the research on new radioisotopes, which can then hopefully be used in pairs for targeted molecular imaging followed up by treatment, using different isotopes from a single element. This combination of diagnostics & therapy, called theranostics, should lead to greater accuracy in patient selection and adapted patient care, often referred to as personalized medicine.

After briefly introducing resonance ionization, I shall present a few recent highlights from the RILIS and CRIS collaborations in the mercury region [8] and indium isotopes [9]. I will then describe how resonance ionization is key in the medical radioisotope production scheme at CERN MEDICIS while describing the current status of this new facility.

References:

[1] J. Levine et al, Int J of Mass Spec 288 (2009) 36.
[2] V.S. Lethokov & C.B. Moore, Sov J Quant Elec 6 (1976) 129.
[3] J. Van Roosbroeck et al, Phys Rev Lett 92 (2004) 112501.
[4] I. Stefanescu et al, Phys Rev Lett 98 (2007) 122701.
[5] M.S. Safronova et al, Rev Mod Phys 90 (2018) 025008.
[6] P. Campbell, I.D. Moore & M.R. Pearson, Prog Part Nucl Phys 86 (2016) 127.
[7] R.M. dos Santos Augusto et al, Appl Sci 4 (2014) 265.
[8] B.A. Marsh et al, Mercurial nuclei get back in shape, accepted for publication in Nature Phys.
[9] R.F. Garcia Ruiz et al, High-precision multi-photon ionization of
accelerated laser-ablated species, accepted for publication in Phys Rev X.