The first components are in: perfect single crystals lent to us kindly by the ILL. The Copper ones are made in-house at the ILL and the Germanium ones are available commercially. But then, they are so perfect that they reflect too few neutrons, so the trick is to make them less perfect. At the ILL they are pressed at high temperature to introduce a controlled ‘micro-cracking’. Like that the whole block will consist of many small perfect crystallites that have slight misorientations with respect to the original orientation. This mosaic spread increases the intensity by allowing a larger wavelength band to be reflected. Unfortunately this also increases the divergence of the reflected beam. Typical mosaic spreads are less than a half a degree, although for instance with graphite crystals you can have 2 or 3 degrees.
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With the detailed planning of the development project of the neutron diffractometer, we also need to know more precisely what the components will cost.
The two most demanding items on the list of instrument components are the neutron detector that needs a high spatial resolution and a monochromator with the right crystalite mosaic.
In a short visit to the ILL we have discussed the possibilities to develop a detector and a monochromator for our needs. On our side, we now need to see what part of that development can be done in-house at the university. This should then clarify how much budget we have to reserve for these components. The collaboration on the development has to be formally signed by both institutes.
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Tagged components, crystals, cu, diffraction, ge, ill, neutron, npm2, rrr, scattering, shopping, tests, tudelft