Transverse emittance systematics measured for heavy-ion beams at ATLAS

The horizontal and vertical beam emittances and ellipse parameters are determined at the ATLAS superconducting heavy-ion linac by the well-known method of measuring the beam width at a profile monitor downstream of a quadrupole magnet as a function of the magnet current. Typically six base-to-base beam widths are measured and used in a least-squares fit to an algebraic expression for the three unknown ellipse parameters. The algorithm was derived from the first order matrix equation for the beam sigma matrix transform through the quadrupole singlet and. Drift to the profile monitor. To date the emittances of five beams from ¹²C⁴⁺ to ²³⁸ U²⁶⁺ have been measured at the entrance of the Positive-ion Injector Linac, yielding normalized values mostly in the range of 0.25-0.30 π mm-mr. These measurements will be extended systematically to several locations to identify possible sources of emittance growth and to develop more systematic beam tuning procedures