Technical Design Report Super Fragment Separator

DRAFT
Figure 2.4.111: Energy deposition per volume in the carbon and iron part of the beam catcher along the
primary beam direction by a 1.5 GeV/u 238 U beam calculated with PHITS [41]. For the sake of clarity the
V-shaped opening of the beam catcher was replaced by a simple block of graphite.
There can be cases where not all high intensity components of the primary beam or fragments can
be stopped in front of the degrader at PF2. This contribution should stay on a level of less than 1 %
of the full intensity of the primary beam to cause no damage for the degrader. However, the subsequent
superconducting magnets have to be protected. Depending on the position and the energy
loss in the degrader the magnetic rigidity of this beam can vary a lot in the second half of the
Pre-Separator. Figure 2.4.112 shows possible trajectories and corresponding options for the beam
catcher locations. At least after the slit at PF4 the total intensity must be reduced to an equivalent of
10 9 uranium ions at 1 GeV/u. Like in the first half it is possible to find a setting of slits in which the
beam is always dumped in a dedicated beam. Some of them need to be movable because they may
otherwise restrict the fragment transmission. The construction of these beam catchers, however, is
much simpler than in the first half of the Pre-Separator. Indeed they can be adopted from the
present FRS slits.
From Figure 2.4.111 with the condition of 100 times less incoming beam intensity, it follows that
the slits must have a thickness of about 30 cm iron. As these slits are not radiated very often higher
density material (tungsten alloys) may also be used without suffering from activation problems.
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