ISIS SANS suite Q-range
24 Sep 2019



Q range for SANS suite instruments at ISIS Neutron Source




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How to choose the Q-range

When choosing your Q range, think also about flux and statistics. Since the neutron flux decays with the inverse of the square of the distance, it will be 9 times higher using 4m sample-detector-distance setup, comparing with 12m setup. Additionally, at 12m setup, we have to use a narrower wavelength range in time of flight mode, which will decrease statistics at low Q. This will be more important for weakly scattering samples. See more about statistics ​scrolling down.


** Merging low and high angle bank; ^extended Qmax​ up to 1 Å-1, using offset det (other scales can be probed by using SESANS).

Q-range vs Statistics

The graph below is a comparison of the scattering from the same sample (our polymer blend standard GDW20) using 12m and 4m sample-to-detector distances at SANS2D beamline. The Q-range improves at 12m setup, and the statistics improve at 4m setup.



Combining FRONT and REAR detectors

The graphs below are showing the superimposition of the scattering intensity recorded by FRONT and REAR detectors at SANS2D beamline. The front detector is used for expanding the Q-range when there is a smooth overlap region between both detectors. MANTID data reduction will merge both intensities generating one only final curve.


Contact: Cavalcanti, Leide (STFC,RAL,ISIS)