Conceptual design of ISOL@MYRRHA 

The scenario is to operate MYRRHA and ISOL@MYRRHA in parallel, which requires a continuous beam splitter. A fraction of up to 5% of the main beam (corresponding to up to 200-μA average current) will be delivered to ISOL@MYRRHA in a pulsed mode with high repetition rate (up to 250 Hz).

ISOL@MYRRHA will follow closely the RIB-production schemes that are developed and successfully used at the ISOLDE-CERN and TRIUMF facilities. It will be equipped with ruggedized target-ion source systems that allow the use of a selection of target materials, including actinide targets, which can withstand the high proton-beam power without compromising the reliability, the longevity, the diffusion and effusion properties, and the yield of particular radioactive isotopes.

Three types of ion sources are foreseen for selective ionization of the products: the hot-surface ion source, the resonant ionization laser ion source (RILIS), and the electron cyclotron resonance ion source (ECRIS). Additional purification occurs by mass separation after extracting the ions over a potential difference of up to 60 kV forming the radioactive ion beam.

In order to make effective use of the beam time, the parallel multi-users aspect of ISOL@MYRRHA is an important issue in the design study. Since a high-resolution mass separator prevents the use of different beams at the same time, a pre-separator with low mass resolution is considered. In this way, one could envisage a scenario in which the low mass isotopes (8Li) are used for solid-state physics in parallel with an experiment using heavier nuclei.

Moreover, the pre-separation avoids a too intense RIB loading of the RFQ cooler and buncher, which allows a high-quality low-emittance beam. As a result, the high-resolution magnet can be maximally exploited with a mass-resolving power M/ΔM in the order of 104.

Proton-beam duty cycle