This last section of the 590 MeV High Intensity Proton Beam Channel is 17 m long and consists of
2 quadrupoles, 1 bending magnet (switch yard for SINQ) used as vertical steering
magnet, 1 horizontal steering magnet, 2 pairs of profile monitors, 1 current
monitor, 4 collimators and a beam dump (see Fig.1, 57
kB). Target E adds 8.5 mrad ( 1 )
to the divergence of the beam. The aperture (24 cm inside the quadrupoles) is
large enough to allow the beam via intermediate waists to grow to a diameter of
4= 40 cm in both directions at the location of
the beam dump ( Fig.2: 13 kB ) .
As can be seen from Fig. 1 the different components are arranged as vertically
removable blocks with up to 2 meters of iron shielding on top of them and their
vacuum chambers connected together with a total of 24 inflatable cushion sealings
( see Fig. 3, 51 kB). (Well visible on this picture
are the two concentric inflatable cushions of one side made out of steel foil with
a grove in between for differential pumping.) This concept has been developed at
PSI by H. Frei et al.
2 and 3 are elliptical (vertical half axis = 80 mm, horizontal half axis =
40 mm) and conical (vertex at the location of Target E) to bring the losses
in the quadrupole duplett (QHG21/QHG22) to a reasonable value. Collimators 0
and 1 protect the mirror plates of the neighboring half quadrupoles for the
secondary beam lines. All collimators are made out of copper and are water
The sum of all proton losses along the first 10 m of this section are 43 %.
(With the target E length
reduced from 60 mm to 40 mm these losses are only 30 %).
Collimator 1 and 2 and the 3 first sections of the beam dump have electrically
insulated electrodes (MHB's, 4 thin nickel foil segments each) fastened to it
to detect - position sensitive - the amount of protons dumped on them. The stopping
of a large amount of protons (~ 20 %) in the collimators produces a considerable halo,
which does not matter to much, if the beam is not deflected with the bending magnet
(AHL) towards SINQ, because in this region all components are radiation
hardened. In case one component here goes defective, it may be removed and
repaired by remote handling (repair work takes place in a special hot cell in the ATEC region).
For the transportation of the highly activated components like targets,
collimators and beam dump segments an iron shielded bottle is available.
Last updated by
Urs Rohrer on 27-Mar-2006