First Elastic Scattering Measurement of ⁸Li on ²⁰⁹Bi at the Australian National University

Abstract

The effects of unusual structures of nuclei, such as neutron halos, on nuclear reaction mechanisms are not well understood, particularly at near barrier energies. Using the SOLEROO Radioactive Ion Beam facility at the Australian National University, below-barrier reactions with 8Li incident on 209Bi have been performed. Beam purities of about 95% are achieved by rejecting unwanted beam species using a solenoidal separator along with tracking and tagging the secondary beam with two parallel plate avalanche counters (PPACs) placed immediately after the solenoid. However, the radioactive ion beam exiting the solenoid is not parallel to the primary beam axis. To obtain a precise angular distribution of elastic scattering, the tracking facility is used to deduce the true scattering angle on an event-by-event basis. The elastic cross-section for 8Li on 209Bi is then extracted, verifying the capability of the facility to perform precise cross-section measurements.