Development of a high ion throughput laser ion source for medical isotope production

Resonance laser ionization does not only yield high efficiencies but also allows selective ionization of a specific element or isotope of interest. Currently, laser ionization is most commonly used in conjunction with a so-called hot cavity: a metal tube which is heated to temperatures of up to 2200 degrees Celsius. A drawback of this method is the efficiency of the cavity as a surface ion source. In some cases, when a sufficiently dense atomic vapor of a surface-ionizable species is present, the ion throughput limit of the hot cavity is reached, thereby inhibiting the survival and/or extraction efficiency of both laser and surface ions. While such limits are less often reached at existing on-line facilities such as ISOLDE, the gradual production and fast extraction cycle of offline facilities such as MEDICIS is more demanding in terms of required ion throughput. The project aims at investigating the limits of the existing hot cavity RILIS process to understand the factors that influence the ion throughput limit. The goal will be to make use of alternative geometries, materials or electrical fields to produce an ion source capable of significantly increased laser-ion throughput. The work will be carried out off-line and on-line with a special emphasis on efficiently extracting lanthanides which are of high interest for medical applications. The work may also include simulations of the electrostatic potentials which are present in the laser-atom interaction region and improvement of the confinement and extraction of laser ionized elements. Investigations of different types of ion sources, e.g. plasma ion sources used at ISOLDE, will also be an area of study.