Neutron Scattering

elated values for the FRJ-2 reactor in Jülich for comparison are (ah,, = 2 - 10 14 n/cm2s at 23
MW .
sion
th ~f rI°i~f r
fL~lll[ 3fl
cI f e.
'21'.ctP_:
rlr.4t tttfa ui 1Y4r
f.=l ,;.f
1ii :td, -< 1-
i ius.f -t r s ip 1,
Figure 2 .5 : Schematic presentation of the fission and spallation process .
In the spallation process highly energetic protons which are typically at energies of about
1GeV hit a target of heavy nuclei like tungsten or tantalum . The proton excites the heavy
nucleus strongly and in the event in the order of 20-25 neutrons are evaporated from such a
nucleus . The energies of the spallation neutrons are typically in a range from several MeV up
to hundreds of MeV. Other than a research reactor, a spallation neutron source can easily be
operated in a pulsed mode, where a pulsed proton beam hits a target . At the spallation source
ISIS at the Rutherford Laboratory for example, the repetition frequency amounts to 50Hz . In
2-7