Study of nuclear reactions with intense, high-purity, low-energy radioactive ion beams using a versatile multi-configuration dual superconducting-solenoid system

A new device (TwinSol) installed at the Nuclear Structure Laboratory at the University of Notre Dame implements a pair of large-bore 6 T superconducting solenoids for producing relatively pure, high-intensity beams of exotic light nuclei at low-energies (10–80 MeV). Typical beams include 8Li and 6He (T1/2<1 s). The device efficiently produces, collects and focuses beams onto (or implants into) suitable target foils and test materials. The system uses various combinations of the following detection schemes: XY position sensitive gas counters for time-of-flight and ion ray-tracing; multiple stacks of silicon surface barrier detector telescopes mounted at various angles on a rotating table; 2D position-sensitive silicon detectors (PSDs) for high precision angular measurements; multi-annular, multisectored “CD” detectors for large solid angle (nearly 2π in lab frame), high-collection efficiency (multi-hit) particle detection; and ion-implanted stacks of target foils for off-line detection. Also available are a set of HPGe detectors which will be implemented upon completion of a low-background gamma cave. TwinSol represents an advancement in the application of large-bore superconducting magnet technology, capable of running in persistent mode for weeks without liquid helium (LHe) refill or measurable degradation of magnetic field (<0.1%).