The next edition of the ISRS Workshop will be held at CERN on 29 November 2022, both "face-to-face" and virtually. The workshop aims to update the scientific community on the present status of the ISOLDE Superconducting Fragment Separator and discuss the physics and R&D program to be developed during the period 2022-2025.
The HIE-ISOLDE facility at CERN can accelerate more than 1000 isotopes of about 70 elements, at collision energies up to 8 MeV/A. The structure and dynamics of nuclear systems far from stability are being investigated by means of Coulomb barrier reactions, nucleon transfer, deep inelastic, and fusion-evaporation reactions. The ISRS collaboration has recently proposed the construction of a novel high-resolution recoil separator, the "ISOLDE Superconducting Recoil Separator" (ISRS). This instrument will extend the physics programme with the more exotic isotopes produced in the secondary target by means of focal-plane spectroscopy.
Fig. 1. HIE-ISOLDE post-accelerator and selected physics topics.
The physics program will entail the detection at ISRS of heavy recoils in coincidence with ions, gammas, and neutrons, making use of the existing detector setups such as the gamma detector array Miniball, the particle arrays GLORIA and T-REX, the neutron detector SAND, the multi-purpose reaction chamber SEC and the particle spectrometer ISS. The plans for a future extension of the experimental hall and the installation of the Storage Ring (TSR) will make experiments with stored secondary beams a reality, and the addition of the high resolving power ISRS spectrometer will make HIE-ISOLDE a unique facility worldwide. The new spectrometer will benefit from Coulomb dissociation, Multinucleon transfer reactions, Deep inelastic, Fusion evaporation, and Breakup reactions to produce nuclei in the energy levels of interest, more exotic even than the impinging radioactive beam, which will be studied by high-resolution focal plane spectroscopy.
The design of ISRS is based on a circular particle storage ring with four 90° bending magnets. When operating in the isochronous mode, the time-of-flight is a direct measurement of the M/Q ratio. Neighboring masses can be separated by a suitable RF system synchronized to the duty cycle, regrouping charge states of selected isotopes and removing the rest.
Fig. 2 Concept design of ISRS and main subsystems
ISRS will operate as an isochronous non-scaling fixed-field alternating-gradient (FFAG) system. The optical lattice allows the transportation and storage of an ion beam with large energy and momentum spread using fixed magnetic fields. Preliminary beam dynamics calculations predict large solid angles > 100 msr and momentum acceptances > 20% from 11Li to 234Ra @ 10 MeV/u, mass resolution better than 1/2000 and large storage efficiency ~ 100%. The ISRS ring uses 90° curved Multifunction Superconducting Canted-Cosine-Theta magnets (CCT) where magnetic fields are superimposed by nesting several tilted solenoids oppositely canted so that the required multipolar fields are produced in the same magnet. The present design has only four CCT units of 1 m radius curvature and 250 mm bore. The dipole field is 2.2 T with a peak field of 4 T, and three alternating quadrupoles with gradients of 13 T/m.
Project co-funded by the Grant PID2021-127711NB-I00 (Spain), the Recovery and Resilience Facility (Spain), and the European Union – NextGenerationEU.