DCS Instrument Performance



Beam Intensity as a function of wavelength and resolution

DCS neutron beam intensity (n/s) as function of wavelength The figure on the left shows the measured neutron intensity (neutrons per second) with all choppers running at 20000 rpm, as a function of neutron wavelength and resolution mode. The sharp dips in the beam intensity at 3.35 Å and 6.70 Å are respectively due to (004) and (002) Bragg reflections in the pyrolytic graphite filter.
The graphite filter is used to eliminate high energy neutrons (for a detailed explanation, please look at the reference The optical filter of the disk chopper spectrometer at NIST JRD Copley and JC Cook (2000) Physica B 283 386-388).
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DCS neutron beam intensity (n/s) as function of wavelength A detail of the short wavelength region is shown.

Energy resolution as a function of wavelength

DCS Energy resolution as a function of wavelength The lines show the calculated FWHM energy resolution for elastic scattering at a chopper speed of 20000 rpm. The points are measured values of the resolution. The lines represent power law fits to the measurements.
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Elastic Scattering Vector, Q, as a Function of Wavelength

Elastic scattering vector, Q, as a function of wavelength The figure on the left shows the upper and lower limits, as well as some intermediate values for the elastic scattering vector as a function of wavelength.
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