PPT Slide
Experiments with liquid jets
The extremely high induced activity levels may well provide the overriding reason for the use of a mercury jet target.
The specific activity is greatly reduced compared to a fixed target (the �band-saw� target is somewhere between the two).
In addition, as proposed by Helge Ravn, the mercury would be distilled to remove most non-volatile spallation products. Volatile products would also be removed from the target area into filters or tanks.
Remember that the tungsten shield around the target must absorb 10 times the beam power in the target itself. A beam dump incorporated into this shield would resemble a spallation or transmutation source target - i.e. another liquid metal system (possibly Hg).
For these reasons we decided to re-construct the Hg jet target.
(gallium/tin and gallium/indium room-temperature liquid metals have been studied. They both have undesirable wetting properties (at least for lab tests) and the former produces an oxide scum)