Exploiting the potential of ISOLDE at CERN (the EPIC project)

The ISOLDE Facility at CERN is the world’s leading facility for the production of radioactive ion beams (RIBs) using the ISOL (Isotope Separation On-Line) method, providing RIBs at energies from 30 keV to 10 MeV/u for a wide variety of experiments. To improve on its capacity to deliver RIBs further from stability, the EPIC project takes full advantage of recent investments by CERN to upgrade the LHC injectors. In particular, the higher proton-beam intensity and energy from the new Linac4 and the PS-Booster upgrade would inevitably produce higher radioactive ion beam intensities further from stability. Sharing the proton-beam between two target stations that simultaneously feed the low-energy and high-energy beamlines will more than double the annual available beam time for experiments. To take further advantage of enhanced beam time, ISOLDE also aims to install a storage ring behind the HIE- ISOLDE post-accelerator to allow the storage of cooled exotic ion beams and thus opening up new possibilities in the fields of astrophysics, fundamental symmetry studies, atomic physics and nuclear physics. This paper outlines the EPIC proposal covering the essential requests for a complete upgrade of the ISOLDE Facility

Proceedings of the XVIIIth International Conference on Electromagnetic Isotope Separators and Related Topics (EMIS 2018), CERN, Geneva Switzerland, 16-21 September 2018

status: publishe

Arc Discharge Ion Source Development at CERN ISOLDE

Within a Marie Curie Early Stage Training project at CERN, a detailed study (experimental, analytical and numerical) of the standard ISOLDE FEBIAD ion sources has been done. A new theoretical model global source behavior could be inferred, based on the acquired experimental data. The source model already served to the development of two FEBIAD prototypes which improved the I+ ionization efficiencies for the noble gases by 5 to 20 times (depending on element) This development can now serve to future ion source optimizations, for specific user or facility requirements around the world, especially for the production of high intensity radioactive beams

Driver beam-led EURISOL target design constraints

The EURISOL (European Isotope Separation Online) Design Study is addressing new high power target design challenges. A three-step method [1] was proposed to split the high power linac proton driver beam into one $H^{-}$ branch for the 4 $MW_{b}$ [2] mercury target that produces radioactive ion beams (RIB) via spallation neutroninduced fission in a secondary actinide target and three 100 $kW_{b}$ $H^{+}$ branches for the direct targets producing RIBs via fragmentation and spallation reactions. This scheme minimises transient thermo-mechanical stresses on targets and preserves the cw nature of the driver beam in the four branches. The heat load for oxides, carbides, refractory metal foils and liquid metals is driven by the incident proton driver beam while for actinides, exothermic fission reactions are an additional contribution. This paper discusses the constraints that are specific to each class of material and the target design strategies

Design of a single magnet separator with mass resolving power mΔm≈20,000\frac{m}{\Delta m} \approx 20,000

ISOLDE at CERN is a leading radioactive ion beam facility. With its upgrade, the HIE-ISOLDE project, an increase in primary beam intensity and energy is envisaged and the aim is a significant increase in intensity of the exotic beams. The high resolution separator (HRS) after the upgrade is required to suppress contaminations almost completely when the masses differ to the beam of interest by Δm/m>1/20,000 . Here a 120° magnet with a bending radius of 1.25 m has been chosen. The magnetic rigidity is 0.625 Tm (B-field of 0.5 T) to allow for separation of molecules of up to a mass of 300 u. The magnet comprises a yoke in wedged H-type configuration for stability and precision and pole face conductors for focusing and compensation of aberrations. The concept was derived analytically, refined with the OPERA 2D software and tested with the ray-tracing module of OPERA 3D

Recent developments in production of radioactive ion beams with the selective laser ion source at the on-line isotope separator ISOLDE

The production of radioactive ionization laser ion source (RILIS) of ISOLDE on-line isotope separation facility was investigated. The RILIS setup included three dye lasers and ionization schemes which employ three resonant transitions were also used. The RILIS efficiency could be reduced by nuclear effects such as hyperfine splitting and isotope shifts. The off-line resonance ionization spectroscopy determined optimal three-step ionization schemes for yttrium, scandium and antimony and antimony. The results show that best ionization schemes of Y provided gain factor of 15 with respect to surface ionization. (Edited abstract) 8 Refs

On-line separation of short-lived beryllium isotopes

With the development of a new laser ionization scheme, it became possible to ionize beryllium efficiently in the hot cavity of the ISOLDE laser ion source. The high target and ion source temperatures enable the release of short-lived beryllium isotopes. Thus all particle-stable beryllium isotopes could be extracted from a standard uranium carbide/graphite target. For the first time the short-lived isotopes /sup 12/Be and /sup 14/Be could be identified at an ISOL facility, /sup 14/Be being among the most short-lived isotopes separated so far at ISOLDE. The release time from the UC/graphite target was studied with several beryllium isotopes. Profiting from the element selectivity of laser ionization, the strong and isotopically pure beam of /sup 12/Be allowed to determine the half- life to T/sub 1/2 /=21.34(23) ms and the probability of beta-delayed neutron emission to P/sub n/=0.48/sub -0.10//sup +0.12/(23 refs)