Technical Design Report Super Fragment Separator

2.4.7 Vacuum
2.4.7.1 General layout
DRAFT
The high-intensity primary beams that will be delivered by SIS100/300 in the final stage of FAIR
require a special layout of the first section of the Super-FRS that contains the production target(s)
and the beam catchers. Following concepts developed at other radioactive-beam facilities (e.g. PSI,
TRIUMF-ISAC, RIKEN-RIBF and GANIL-SPIRAL), we will apply the ''plug'' concept in the
Pre-Separator up to PF1. This concept involves:
• a combination of beam-line inserts (targets, beam-catchers, slits, diagnostic detectors etc.)
with local mobile shielding that can be removed as one unit (''plug'');
• a compact shielding of the beam lines and vacuum chambers;
• vertical insertion of the plugs along rails into the vacuum chambers;
• vacuum seals and media connection in a moderate-radiation area above the local shielding
that can be serviced manually after shutdown.
Schematically, this concept is depicted for the production-target area in Figure 2.4.123. The
compact shielding reduces the shielding volume (and thus cost) and avoids air activation. Plugs can
be removed individually from their common vacuum chamber. The vacuum chamber itself can be
separated from the beam line by inflatable “pillow seals”. A similar scheme will be applied to the
beam-catcher modules which are located in the sections between the first dipole magnets and at the
Pre-Separator degrader unit.
The positions of the pillow seals in the Super-FRS are indicated by the positions 1 to 13 in Figure
2.4.88. Elastomer seals can not be used because of the radiation level in this area. A test stand to
measure the leak rate of a 200 mm pillow seal is shown in Figure 2.4.89.
The leak rate of the pillow seal was determined in dependence of the contact pressure and the
surface roughness of the seal and the counterplates, respectively. The best achieved leak rate so far
is approximately 3 × 10 -6 mbar·l/s.
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