Probing the structure of short-lived nuclei with single-nucleon transfer reactions is a key focus of existing and emerging radioactive-ion-beam facilities. In this scenario, the reactions are performed in inverse kinematics where conventional approaches typically suffer from poor resolution due to significant kinematic compression. The HELIOS spectrometer at Argonne National Laboratory sidesteps the kinematic-compression problem by transporting the outgoing ions in the strong, homogeneous magnetic field of a large-bore superconducting solenoid. These ions follow helical trajectories before returning to the magnetic axis, where their energy, position, and time-of-flight are measured---the latter providing automatic, energy independent, particle identification via the cyclotron period of the ion. At Argonne, light radioactive ion beams are produced via the ‘in-flight’ technique giving access to neutron-rich and deficient sd-shell nuclei and beyond. For heavier nuclei, the new CARIBU facility will provide re-accelerated Cf fission fragments for use in transfer reactions. In conjunction with HELIOS, this opens up many exciting opportunities. An overview of the HELIOS spectrometer will be presented along with results from the first measurements with light- and medium-mass beams. The latest prospects for a HELIOS-like spectrometer at a European ISOL facility will be discussed.
