Isolde Superconducting Recoil Separator (ISRS)

The HIE-ISOLDE facility at CERN accelerates over 1000 isotopes from around 70 elements, reaching collision energies up to approximately 10 MeV/A, making it an excellent platform for exploring nuclear theories through optimal (N, Z) combinations. The ISRS collaboration has proposed constructing a new high-resolution recoil separator called the “ISOLDE Superconducting Recoil Separator” (ISRS), aiming to expand the physics program to study more exotic isotopes generated in the secondary target. This involves combining focal plane spectroscopy with particle and photon detection using various detectors at HIE-ISOLDE.

2. PHYSIS PROGRAM

Various reaction mechanisms can be employed to investigate nuclear structure and reactions of exotic nuclei. Transfer reactions in inverse kinematics have high cross sections at HIE-ISOLDE beam energies. Fragment angular distributions are highly sensitive to nuclear wave-function details like energies, angular momenta, and spectroscopic factors. They can, for instance, help study the evolution of nuclear structure and reactions relevant for nucleosynthesis around closed shells N ≈ 82 and N ≈ 126. Multinucleon transfer processes through deep inelastic, quasi-elastic, and quasi-fission reactions can produce significant levels of interest in exotic nuclei, including regions near the drip line around 78Ni and the N = 126 closed-shell region, which are crucial for studying shell-quenching and the astrophysical r-process. Charge-exchange reactions enable the investigation of spin and isospin excitations, the structure of particle-hole states, and scalar and isovector components of nuclear matrix elements relevant for nuclear beta decay, thus connecting strong and weak interactions. Fusion-evaporation reactions can yield very exotic residues, and the ISRS spectrometer provides an opportunity to perform lifetime measurements with plungers. Both direct and inverse kinematics with light or heavy targets will be used, necessitating the spectrometer’s ability to rotate to cover a range from zero to typical heavy-ion grazing angles (∼50° – 70° Lab).