Figure 2
Experimental neutron reflectivities plotted as a function of
for: the control sample (
), the specimen broken at a stress intensity factor
(zone 1, ●) and for the specimen broken at a stress intensity factor
(zone 2, blue squares). We have superimposed to the experimental curve corresponding to the control sample the theoretical Fresnel reflectivity curve (red plain line) as well as the result of the second order Born approximation (red dashed dotted line). The experimental results corresponding to zone 1 and zone 2 are fitted using Eqs. (
3,
5,
6), and are fitted by a dashed green line and a black dashed dotted line, respectively. The best fits correspond to
,
and
in zone 1, and
,
and
in zone 2. Inset: Contour lines of the fit root-mean square error in the plane (
,
) in zone 2, showing that while the combination
is rather well pinned down by the fit,
is a “soft” direction. The relative experimental rms error per point is 0.075, whereas the minimum relative error achieved by the fit is 0.06.
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