Technical Design Report Super Fragment Separator

DRAFT
Figure 2.4.79: Total Neutron Flux (all energies) per incident particle in the target area of the Super-FRS
(detector positions at z = -55 cm and z = -110 cm, target at z = 0 cm, beam collimator starts at z = 30 cm).
The values are given for 1500 MeV/u 238 U ions hitting a 4 g/cm 2 carbon target. The material of the target
chamber and nearby shielding is iron, the outside is concrete.
2.4.6.1 Diagnostics target area and beam catchers
For the target and beam catcher area it is foreseen to have a safety interlock on the nominal beam
position on target and beam catcher to avoid damage to any component in the high radiation areas.
It is clear, especially for the short extraction with 50 ns pulses, that any detector material or foil will
fail if hit by the full beam intensity. Therefore, contact-free measurement methods have to be used.
Target monitor
For the beam spot on target monitoring an optical imaging technique in the infrared spectrum is to
be developed together with the target types. As the camera has to be placed a reasonable distance
from the target to avoid radiation damage, a fibre or mirror optics has to be developed. The camera
images are than analyzed using standard methods.
Another interesting method to visualize and monitor the beam spot on the target makes use of the
surrounding residual gas. The induced fluorescence in the residual-gas volume may be used to
deduce the profile of the incoming beam. This method has been successfully applied (Figure
2.4.80) at the UNILAC at GSI [20]. For application to the Super-FRS a camera and image intensifier
have to be placed in safe distance from the target and a suitable telescope or fibre optics has to
be developed.
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