ANL, Argonne, Illinois, USA
LSU, Baton Rouge, Louisiana, USA
Radioactive ion beams (RIB) at the Argonne Tandem Linear Accelerator System (ATLAS) are produced either from the in-flight method at 5-15 MeV/u for A < 30, or via reacceleration of fission fragments from the CAlifornium Rare Isotope Breeder Upgrade (CARIBU) at 4-10 MeV/u for 80 < A < 160. These RIB are typically accompanied by contaminant beams >100x more intense. The goal of this work is to develop a fast (>105 pps), compact (retractable from the beam line) particle detector capable of A and Z identification to enable accelerator optimization on the exact species of interest. The detector should have an energy resolution of ≤5% and be resistant to radiation damage. A gas ionization chamber supplemented with an inorganic scintillator was chosen as the basic conceptual design. GSO:Ce was chosen as the primary candidate scintillator due to a demonstrated energy resolution of ~3% for 15 MeV/u He and less irradiation induced performance degradation than other candidate materials.
ANL, Argonne, Illinois, USA
The efficient and rapid production of a high-quality, pure beam of highly charged ions is at the heart of any radioactive ion beam facility. An ECR charge breeder, as part of the Californium Rare Ion Breeder Upgrade (CARIBU) program at Argonne National Laboratory, was developed to fulfill this role. The charge breeding efficiency and high charge state production of the source are at the forefront of ECR charge breeders, but its overall performance as part of the accelerator system is limited by a pervasive stable ion background and relatively long breeding times. Steps have been taken to reduce the level of background contamination but have met with limited success. As such, an EBIS charge breeder has been developed and is now running in an off-line configuration. It has already demonstrated good breeding efficiencies, shorter residence times, and reduced background, and it is scheduled to replace the ECR charge breeder in late 2015. The resultant change in duty cycle and time structure necessitates changes to the overall facility operation. The experiences with these breeders their strengths, their weaknesses, and the possible paths to further improvement - will be discussed.
