The China Spallation Neutron Source (CSNS) probes material structure and dynamics across physics, chemistry and materials science. In time-of-flight experiments, a single measurement can generate billions of raw events, which must undergo complex corrections—absorption, multiple scattering, detector efficiency, background—before yielding scientific quantities such as diffraction patterns, pair distribution functions (PDF) or dynamic structure factors.
A team led by Rong Du at the Institute of High Energy Physics, Chinese Academy of Sciences, and the Spallation Neutron Source Science Center now reports RZera 3.0, a major upgrade of the Rongzai Era software first introduced for total scattering data reduction at CSNS.
The core innovation is a unified, modular dataflow architecture. Instead of the original "one-click" paradigm, the reduction pipeline is split into discrete modules that users can execute, inspect or bypass, with each step's output plotted to monitor its evolution—giving beamline scientists transparency and control while retaining a quick-reduction mode for routine users.
Three advances follow. First, for PDF analysis, RZera 3.0 integrates a Hermite function fitting method that exploits Hermite functions being eigenfunctions of the Fourier transform. Data from all detector groups are fitted simultaneously, each convolved with its own resolution function, producing a PDF effectively deconvolved from instrumental resolution and free of manual-stitching artifacts. Tests on a standard silicon sample achieved refinement quality comparable to a well-optimized conventional workflow (Rwp 12.54% versus 12.36%) while eliminating low-r oscillations and operator dependence.
Second, an automated attenuation correction algorithm for cylindrical sample cells accounts for the sample's attenuation of the cell's scattering at each detector pixel, based on a geometric scattering model and the Beer-Lambert law. Tests on the NIST SRM 640d silicon standard showed reduced Rietveld Rw values across low-, middle- and high-angle detector groups.
Third, RZera 3.0 extends beyond powder diffraction for the first time with a complete workflow for the high-energy direct geometry inelastic spectrometer (HD), China's first time-of-flight inelastic neutron scattering spectrometer. The workflow transforms raw events into the dynamic structure factor S(Q,E); a comparison of the same sample measured at CSNS-HD and ISIS showed excellent agreement.
RZera 3.0 is now deployed across the multi-physics, high-pressure and high-resolution powder diffractometers and the HD spectrometer, providing offline and online reduction through a consistent interface under a "unified architecture, specific instrument" design. Online tools include real-time data viewers, beam monitoring and an AI-based indexing tool for predicting crystal system, space group and lattice.
The authors note that RZera 3.0 has evolved from a single-instrument tool into a centralized platform serving a significant portion of the CSNS user community, with an open, modular framework designed for collaboration and future algorithm integration. Source code, user manual and test data are available at https://github.com/unitesc/RZera.
Method of Research
Computational simulation/modeling