Neutron Scattering

corrections for the ideal case can easily be performed . The example is given for the case
of coherent scattering and spin-incoherent scattering . From the flipping ratio of non-spin
flip scattering to spin-flip scattering from either a purely coherent scatterer or a purely
incoherent scatterer the polarization factor of the experimental set-up can be determined .
One should note that multiple scattering may alter the expected ideal final polarization as
soon as spin-flip processes are involved . Silice from polarization analysis the information
on both scattering channels is available, the possible corrections for multiple scattering
are more reliable as compared to unpolarized experiments .
coherent scattering
spin-incoherent scattering
magnetic scattering
I_ 9 - 2 (I+_ - I+
2(I1 + -II++ ) -'
I
N
C
N
i
i
i i
i
i
i
i
Figure 4 .5 :
1 0 1 0 1
P P P
Non-ideal experimental conditions for polarization analysis shown for coherent,
spin-incoherent and paramagnetic scattering .
The polarization factor of the instrument,
P < Pideat = 1, can be determined from the flipping ratio SF:NSF for a coherent scatterer,
and one can extrapolate to the ideal conditions .
Furthermore, one should mention the possible interference of nuclear and magnetic
scattering amplitudes ; an example will be given below . The interference properties are
especially of importance for polarizers . Since coherent nuclear scattering is only observed
in non-spin flip scattering, the interference terni cancels as well for the spin-flip scattering .
In general, for studies of more complex magnetic systems, e .g. with with non-collinear,
chiral structures or excitations, interference of nuclear and magnetic interference a complete
vector polarization may be necessary [2, 3] . Therefore one has to determine the 3 x 3
Matrix given by the incident and final polarization vector .
4- 1 1