HIE-ISOLDE HEBT beam optics studies with MADX

Beam design and beam optics studies for the HIE-ISOLDE transfer lines [1, 2] have been carried out in MADX [3], and benchmarked against TRACE 3-D results [4, 5, 6]. Magnet field errors and alignment imperfections leading to deviations from design parameters have been treated explicitly, and the sensitivity of the machine lattice to different individual error sources was studied. Errors of different types have been considered and their effects on the machine have been corrected [7]. As a result, the tolerances for the various error contributions have been specified for the different equipment systems. The design choices for the expected magnet field and power supply quality, alignment tolerances, instrument resolution and physical apertures were validated. The baseline layout contains three identical branch lines as presented in Fig. 1. The detailed beam optics study with MADX was carried out for the beam line XT01. The large energy range from 0.3 to 10 MeV/u requested for the experiments sets a number of challenging constraints on the beam optics design. The facility is optimized for energies 5.5 and 10 MeV/u. However, some experiments will be carried out at 0.3 MeV/u, where the beam emittance is rather large. Thus the beam transmission at the low energy of 0.3 MeV/u was studied in detail. The dependence of the beam transmission on the geometric beam emittance was investigated. Beam sizes at the target for different energies were estimated and compared with the design values for experiments. All simulations were done for a mass-charge ratio A/q=4.5, representing the most demanding beams for field specification. The methodology and results of the studies are presented. The study details and complementary material are documented in Appendix. MADX beam optics simulations are found on DFS [9].