Status of the focusing system in front of the Super-FRS target

Justus Liebig University, Giessen, GermanyThe design and layout of the focusing system before the Super-FRS target has been re fined and modifi ed from the preliminary studies presented in Refs. [1,2]. First one should note that the split-unit design, using Super-FRS and SIS100 superconducting quadrupoles, has been adopted. Certain quadrupoles within a unit may be switched off, depending on the magnetic rigidity. The modifications to the lattice have resulted from the request to add two steerer magnets, one vertical and the other horizontal, and a diagnostic chamber. In addition, the desire to make the cryostats for the triplets and dou-blet+steerers the same length (5.6 m, including flanges), has resulted in a further adjustment. The new layout with respect to the building is shown in Fig. 1. In the figure, the beam from the coupling line from the synchrotron enters from the left. The focusing system starts with a doublet of SIS100-type 130-mm radius quadrupoles. Then follow a doublet and two triplets of Super-FRS-type quadrupoles. The wall in front of the doublet+steerers will be thinner and located further upstream than shown in Fig. 1. Figure 1: Plan view of the doublets and triplets of the fo-cusing system with respect to the building walls and shielding. The cryostats for the Super-FRS type magnets are made transparent to show the magnets within. The two superferric steerer magnets TFF1KH02 and TFF1KV02, coloured in purple in Fig. 2, are placed either side of the quadrupole doublet TFF1QS04-05. They are similar to the steerer magnets in the Super-FRS: 500-mm effective length, 380-mm by 240-mm usable aperture. The spacing between the quadrupoles and the steerers is ar-ranged to fill a standard Super-FRS triplet cryostat. The diagnostic chamber will be approximately 500 mm long and located as indicated in Fig. 1. It could be instru-mented with, for example, a removable beam profiler and a viewing phosphor screen. Figure 2: Example ion-optics of the focusing system (“8Q” mode). Upper part: horizontal plane; lower part: vertical. The two unused quadrupoles are uncoloured. The 1