Laser-ionized Radioactive Ion Beams at Day 1 of ISOL@MYRRHA

ISOL@MYRRHA is an Isotope Separation On-Line (ISOL) facility, under construction at SCK CEN.

When bombarding hot target materials with 100 MeV protons, it produces, evaporates, ionizes and accelerates isotopes into Radioactive Ion Beams (RIBs), which can be used for fundamental physics, solid state research, medical developments,…

At the start of the facility, the isotopes will be ionized within a 'hot cavity' using either surface ionization or resonant laser ionization. In the last few years we focused on a better understanding of the plasma in this cavity when used as a surface ion source, and we improved an existing design using this understanding. However, factors that aid surface ionization, not necessarily help for ionization and extraction of laser-ionized isotopes. In fact, a surface-ionized background has shown on several occasions to be harmful to the production of such laser ions.

An interesting element to laser ionize in first experiments would be scandium. For example in nuclear spectroscopy, a precise measurement of octopole moments over a series of Sc-isotopes would increase our understanding of phenomena at play in the atomic core. ISOL@MYRRHA can, amongst other elements, aim to produce the relevant scandium isotopes, both neutron deficient and neutron rich, in its first days of operation. However, both the laser ionization efficiency and the purity of the resulting mass separated ion beam will suffer from easily surface-ionized isobars as K, Ca or simply from massively present Ti, a potential target material for making Sc-beams.

This PhD research aims at studying the production and then specifically the ionization and extraction into a beam of elements such as Sc, relevant for the future physics cases at ISOL@MYRRHA. From there the aim is to identify work points and to design and test solutions that deal with these.

This research is part of a collaboration between SCK CEN and CERN. The student will mainly work at SCK CEN in Mol with its recent test facilities, and occasionally at KULeuven. In addition, the student will go to CERN for extended periods and get first-hand experience at ISOLDE, one of the most renown and innovative operational ISOL facilities in the world.

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