Technical Design Report Super Fragment Separator

DRAFT
Separation performance with two degrader stages
The two-stage system has several novel functions and features:
• reduction of the contaminants from fragments produced in the first degrader;
• optimization of the fragment rate on the detectors in the Main-Separator;
• introduction of another separation cut in the A-Z plane of the separated isotopes;
• Pre- and Main-Separator can ideally be used for secondary reaction studies if the separation
of the Pre-Separator is already sufficient.
Figure 2.4.9: Separation performance of the two-degrader method compared with a one-degrader setup,
for the 100 Sn example, taken from ref. [4].
The example shows the separation of 100 Sn produced by fragmentation of 124 Xe at 1000 MeV/u.
The large number of secondary fragments for a single degrader stage is illustrated by using the
Main-Separator only (gray boxes). The total amount of unwanted secondary fragments exceeds the
separated 100 Sn rate by a factor of 10 4 . In case the Pre-Separator is used in addition, only the few
primary fragments, marked with red boxes, are transported to the final focal plane.
The resulting Super-FRS system thus is a most powerful isotope separator and in addition a versatile
high-resolution spectrometer. This operation mode has been very successfully applied also
in several categories of experiments at the present FRS [1]. Several basic discoveries have been
made with the FRS as spectrometer, e.g., new halo properties, deeply pionic states in heavy atoms,
relation of fragmentation and EOS, new basic atomic collision properties at relativistic energies,
etc. Such achromatic systems are ideally suited for high-resolution studies independent of possible
energy fluctuations of the primary beam.
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