Tuesday 3 May 2011, 3.15PM
Speaker(s): Dr Ben Kay, Dept of Physics
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. Conventional approaches of measuring the outgoing ion as a function of laboratory angle unavoidably result in poor resolution due to significant kinematic compression.
The HELIOS spectrometer, recently developed at Argonne National Laboratory, avoids these complications 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 provides automatic particle identification being the cyclotron period of the ion. Measuring the energy as a function of distance from the target side steps the kinematic compression problem.
An overview of the HELIOS spectrometer will be presented, along with results of the first (light) radioactive-ion-beam experiments, and the initial exploration of transfer reactions with heavy stable beams. Future prospects will be discussed including the possibility of a HELIOS-like spectrometer for a European ISOL facility.
(image shows a schematic of the HELIOS spectrometer)