Irena — Tools for analysis of small-angle scattering data

Irena is a set of tools for data manipulation and analysis of small-angle scattering (SAXS, SANS, USAXS, USANS) and powder diffraction (XRD, WAXS) data. It is mostly used for analysis of data in materials science, chemistry, polymers, metallurgy, physics, and other systems of typically solid or liquid samples. It addresses complex systems with size distributions, hierarchical structures, diffraction peaks, etc.

Irena also contains a simple X-ray and neutron reflectivity tool (for more complex systems use Motofit) and a set of tools for bioSAXS users — it can use its own tools or gnom from the ATSAS package to generate PDDF. More bioSAXS tools may be added.

Irena requires the commercial package Igor Pro 9.0x or 10.x from Wavemetrics, Inc.

Prefer Python? pyIrena is a Python package for macOS, Windows, and Linux — a conversion of the Irena tools using Anthropic Claude, verified against Irena. More details here.

Current version and installation

Current version: 2.75, released 6/21/2026 (June2026 release). Current beta version: n/a.

Igor Pro 9.05 and 10.x

Additional downloads

• Test data for the YouTube channel tutorials: Size Distribution tool test data; for other tools, browse the ExampleIgorExperiments folder.
• User form factors for the Modeling tool: download the ones you need from this GitHub location. If you develop one and can share it, please send it to the author to be included.

Older Igor versions (no development anymore)

• Igor 8.x — use release June2025 with GithubInstaller v1.17.
• Igor 7.08 — obsolete; please upgrade Igor Pro. If you must stay on 7.08, use GithubInstaller v1.10 and install version 2.69 (February2020 release) — higher versions are not tested in Igor 7.08 and may not work. Check the YouTube channel for instructions.

What is included

Analysis tools

• Unified fit
• Modeling — direct modeling of SAS from up to 10 populations on up to 10 data sets at once. Selection of form factors and structure factors, Unified fit, mass or surface fractal, and diffraction peaks.
• Size distribution — using Maximum Entropy, TNNLS, and Regularization
• Guinier-Porod model
• Fractal model — combination of mass and surface fractals
• X-ray and neutron reflectivity — using Parratt's recursive method
• Small-angle diffraction tool — up to 6 diffraction peaks
• Powder diffraction peak fitting tool (WAXS)
• System-specific models — Debye-Bueche; Ciccariello-Benedetti; Teubner-Strey; Hermans, Modified Hermans, and Unified Born Green (correlated lamellae systems)
• Pair distance distribution function (PDDF, P(r))
• Hermans orientation parameter — see e.g. Macromolecules 2004, 37, 5327–5336, formula 1
• Visualization tools — Mass Fractal Aggregate: 3D Monte Carlo shape reconstruction
• bioSAXS analysis — basic/simple fits (Guinier, Porod, ...); PDDF/molecular weight using GNOM and other tools

Support tools

• Data import — from ASCII & XML (CanSAS XML) files
• Data export — to ASCII or NXcanSAS (data only) files
• HDF5 Browser —  copy data between HDF5 files and HDF5 file and Igor experiment
• Data plotting — 2D, 3D, can create movies of plots
• Data manipulation — merging of two overlapping data sets (SAXS curves from different distances, etc.); subtract, scale, multiply, etc.
• Scattering contrast calculator — including anomalous effects using Cromer-Liberman code
• Desmearing — using the Lake method
• Data "mining" tool, metadata browser, etc.
• Scripting tool — runs Unified fit, Modeling II, Plotting tool, and Size distribution automatically on multiple data sets
• bioSAXS support — import simple ASCII; average multiple measurements; subtract buffer and scale; concentration extrapolation tool

For a more detailed description, see the Irena introduction.

Documentation and help

• On-line manual — read it in your web browser: http://saxs-igorcodedocs.readthedocs.io
• Wiki — for the Irena and Nika packages on the GitHub repository. Questions of general importance may already be answered there.
• Help movies — try my YouTube channel
• Igor Pro help — check the Wavemetrics YouTube channel
• Mailing list — to be informed about Irena updates and to ask about SAXS/SANS analysis problems, join the irena_users group
• Workshops — since 2012 we organize 1–3 workshop sessions per year at the APS on the use of the Irena and Nika packages. The next workshop is being considered.
• E-mail the author a question

Disclaimer

This set of macros is being developed for use on any SAS data. Their use by anyone for open science is free of charge. If you want to use them for proprietary work, please contact the author for permission. There are no warranties with respect to the functionality of these macros; please verify all results by independent methods.