On 09/21/11 16:28, Sean Seaver wrote:
Dear Rex,
1. What are the limits to data set completeness imposed by a Laue experiment
versus those of monochromatic data collection?
Laue allows for a greater number of Bragg reflections to be measured compared
to monochromatic data collection over a give time period. The limiting factor
in neutron crystallography in regards to data completeness is predominately
collection time and instrumentation (detector size).
With X-rays, Laue diffraction leads to some systematic overlap as
reflections from different wavelengths fall on the same detector
position, and this cuts into completeness.
With neutrons, it is possible to use a time-resolved detector such that
all events are time-stamped, and the reflections from lower energy
neutrons do not overlap with those of higher energy neutrons (neutrons
having measurable mass, and thus noticable velocity differences). I
know that this is possible, I do not know whether it is commonplace.
See, for example:
Protein crystallography with spallation neutrons: the user facility at
Los Alamos Neutron Science Center (2004) P. Langan, G. Greene & B.P.
Schoenborn, J. Appl. Cryst. 37(1) 24-31.
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All Things Serve the Beam
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David J. Schuller
modern man in a post-modern world
MacCHESS, Cornell University
[email protected]
