Technical Design Report Super Fragment Separator

DRAFT
maintenance of the carbon or iron is possible with manipulators inside the hot cell.
With a total height of the whole plug of about 2.5 m and the largest beam catcher being 70 cm long
and 45 cm wide the total weight of the shielding bottle including the iron plug inside is about 35
tons.
The cooling water must be kept in a closed circuit as it becomes activated. The heat exchanger
capable of removing 60 kW and keeping the water at room temperature will be located at the top of
the shielding plug in the maintenance tunnel. The water pipes lead through the plug. The water is
not so much activated thus it is sufficient to place the heat exchanger behind an iron shielding of 10
cm thickness.
2.4.11.2 Degrader systems and ion-catcher
The degrader systems are key components for the isotopically pure in-flight separation. Their
effect and the ion-optical properties have been described in detail in ref. [58]. A newly implemented
feature is the slowing-down, thermalization and post-acceleration of exotic nuclei employing
a helium-filled stopping cell at the Low-Energy Branch. For this hybrid system, which will
combine the advantages of the in-flight separation and isotope-separation on-line, a monoenergetic
degrader system will be used. Existing techniques will be further developed and adapted to the
performance of the Super-FRS. This concerns mainly the mechanical dimensions and thermal
stress and radiation damage due to higher beam intensities. The numbers given in the following are
based on calculations assuming the separation of exotic nuclei ranging from 11 Li up to 232 Rn. The
range of specific kinetic energies and thicknesses is given in the following table.
Thickness
Energy range
in units of range
(MeV/u)
PF2 0.1 ... 0.5 1000 ... 1500
MF2 0.1 ... 0.5 500 ... 1000
MF11 0.1 ... 1.0 100 ... 500
Figure 2.4.116 shows the generic concept of the degrader systems to be used at the central focal of
the pre- and main-separator, PF2 and MF2, respectively, and at the final focal plane MF11 of the
energy buncher. The unit consists of several components fulfilling different purposes: a rotational
stage with two wedge-shaped disks of opposite rotation, thus allowing to vary the thickness continuously
along the dispersive direction (indicated by the angle α), and two wedges moving linearly
in opposite direction thus causing a continuously varying homogeneous thickness (d). In
addition to that, homogeneous or wedge shaped pieces of material can be added (not shown in the
figure) in order to provide larger thicknesses and/or angles.
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