The LIEBE high-power target: Offline commissioning results and prospects for the production of 100Sn ISOL beams at HIE-ISOLDE

With the aim of increasing the primary beam intensity in the next generation Radioactive Ion Beam facilities, a major challenge is the production of targets capable of dissipating high beam power, particularly for molten targets. In that context, a direct molten loop target concept was proposed for short-lived isotopes for EURISOL. The circulation of molten metal enables the production of droplets enhancing the radioisotope diffusion. The concept also includes a heat exchanger ensuring thermal equilibrium under interaction with high proton beam power. A target prototype, named LIEBE, has been designed and assembled to validate this concept in the ISOLDE operation environment. The project is now in an offline commissioning phase in order to confirm the design specifications before tests under proton beam. Successful outcome of the project can lead to new beams with great interest in nuclear structure and physics studies. In particular, investigations fall short in the region around the double magic isotope 100Sn at ISOL facilities because of the lack of a suitable primary beam driver and target-ion source unit for any of the present-day facilities. Achievable 100Sn beam intensities and purities are calculated with ABRABLA and FLUKA considering the use of a high power molten lanthanum target combined with molecular tin formation and a FEBIAD ion source. The presented option takes into consideration upgrade scenarios of the primary beam at ISOLDE, going from a 1.4  GeV–2 μA to a 2 GeV–4 μA pulsed proton beam.