Tuning the Superconducting Linac at Low Beam Intensities

The ANU Heavy Ion Accelerator Facility (HIAF) is comprised of a 15 MV electrostatic accelerator followed bya superconducting linac booster. Employment of double terminal stripping allows the system to accelerate beams with mass up to 70 amu. The disadvantage of double terminal stripping is low beam intensity of few particle nanoamps delivered to the linac. One of the linac set up procedures developed at ANU utilises a U-bend at the end of the linac. One special wide Beam Profile Monitor (BPM) is installed after the 90 degree magnet. The technique allows correct setting of phase by observing the displacement of beam profile versus phase shift of the last phase locked resonator. In this paper, a simple method has been proposed to improve sensitivity of a commercially available BPM for efficient operation with low beam intensities. Verification of BPM with enhanced sensitivity is accomplished during routine linac operations and it is supplemented by longitudinal phase space simulations.This work has been supported by Australian Federal Government Superscience/EIF funding under the NCRIS mechanism