Implementation of cross correlation for energy discrimination on the time-of-flight spectrometer CORELLI

Abstract

1 This article will form part of a virtual special issue on advanced neutron scattering instrumentation, marking the 50th anniversary of the journal.Keywords: neutron diffraction; energy discrimination; cross-correlation technique; time-of-flight neutron beamlines.Implementation of cross correlation for energy discrimination on the time-of-flight spectrometer CORELLI The CORELLI instrument at Oak Ridge National Laboratory is a statistical chopper spectrometer designed and optimized to probe complex disorder in crystalline materials through diffuse scattering experiments. On CORELLI, the high efficiency of white-beam Laue diffraction combined with elastic discrimination have enabled an unprecedented data collection rate to obtain both the total and the elastic-only scattering over a large volume of reciprocal space from a single measurement. To achieve this, CORELLI is equipped with a statistical chopper to modulate the incoming neutron beam quasi-randomly, and then the cross-correlation method is applied to reconstruct the elastic component from the scattering data. Details of the implementation of the cross-correlation method on CORELLI are given and its performance is discussed.

Experimental signatures of a three-dimensional quantum spin liquid in effective spin-1/2 Ce2Zr2O7 pyrochlore

“…Diffuse neutron scattering. Diffuse neutron scattering experiments were performed on a 2.3 g floating-zone-grown Ce 2 Zr 2 O 7 single crystal using the elastic diffuse scattering spectrometer, CORELLI, at the Spallation Neutron Source, ORNL 56 . The sample was aligned in the (h, h, l) scattering plane on an oxygen-free copper holder and the temperature was regulated using a 3 He inset.…”

Machine-learning-assisted insight into spin ice Dy2Ti2O7

“…One piece of crystal with the mass ≈ 200 mg was aligned in the (111) plane for the neutron investigation at the single crystal diffuse scattering spectrometer CORELLI at the Spallation Neutron Source, Oak Ridge National Laboratory. The crystal was prepared as a sphere to minimize absorption corrections and demagnetization corrections.CORELLI is a time-of-fight instrument where the elastic contribution is separated by a pseudostatistical chopper[27]. The crystal was rotated through 180 degrees with the step of 5 degree horizontally with the vertical angular coverage of ±8 degree (limited by the magnet vertical opening) for survey on the elastic and diffuse peaks in reciprocal space.…”

Ultrafast calculation of diffuse scattering from atomistic models

“…In each case, I(G) was calculated using the FFT, and I(Q) was then estimated using Eqs. (13) and (44)- (46). The corresponding cutoff functions are shown in figure 1(d)iii and 1(d)iv.…”

“…In the context of sampling theory, Eqs. (12) and (13) are known as the Whittaker-Shannon interpolation formulae. They show that the scattering intensity can, in principle, be reconstructed at any wavevector Q, given only its samples at the supercell Bragg positions {G}.…”

“…I first recall that I(Q) can, in principle, be calculated at any wavevector Q given only its samples at the supercell Bragg positions {G}, by applying the Whittaker-Shannon interpolation formulae, Eqs. (12) and (13). Consequently, I(G) can be calculated using the FFT and then resampled to obtain I(Q) on a fine grid.…”