Technical Design Report Super Fragment Separator

DRAFT
movable, but BC3 must be able to act like a slit to catch the primary beam also in cases where it is
less than 15cm way from the optical axis.
Figure 2.4.103: Trajectories of primary beams with different δp in steps of 2 % calculated with the ion-optical
program GICOSY [42]. The red rays represent possible separation scenarios for uranium beams and the
purple rays hold for lighter ions with Z < 9 to produce neutron-rich fragments. Note, due to the different scale
in longitudinal and transverse direction the angles are not conformally represented.
2.4.11.1.2 Separation of fragment beams
Many Monte Carlo simulations of the primary and fragment beam distributions using the code
MOCADI [6] were performed to make sure that the beam-catcher system is universal for exotic
nuclear beam experiments. A special challenge is to cope with heavy primary beams still carrying
electrons after penetration through the target. An example is presented in Figure 2.4.104, for a 238 U
beam after passing a 4 g/cm 2 lithium target at 1500 MeV/u. The Super-FRS is set to separate 132 Sn
fission fragments and the primary beam still populates mainly 3 charge states, 92+, 91+ and 90+.
In principle, an efficient separation scheme relies on a large Bρ difference between the primary
beam and the fragment beam, but in this case the beam catcher will reduce also the transmission of
the selected fragments.
Figure 2.4.104: Calculated beam spot of 238 U primary beam with three atomic charge states and of the
fragment beam 132 Sn set. The beam catcher is moved in from the left hand side to intercept the primary
beam.
111