Advanced Photon Source

An Office of Science National User Facility

Irena: Small-Angle Scattering Data Analysis

Modeling of three concentrations of nearly monodispersed suspension of silica particlesIrena is a tool suite for analysis of both X-ray and neutron small-angle scattering (SAS) data. It runs within the commercial Igor Pro framework to bring together a comprehensive suite of tools useful for investigations in materials science, physics, chemistry, polymer science and other fields. In addition to Guinier and Porod fits, the suite combines a variety of advanced SAS data evaluation tools for the modeling of size distribution in the dilute limit using maximum entropy and other methods, dilute limit small-angle scattering from multiple non- interacting populations of scatterers, the pair-distance distribution function, a unified fit, the Debye–Bueche model, the reflectivity (X-ray and neutron) using Parratt’s formalism, and small-angle diffraction. There are also a number of support tools, such as a data import/export tool supporting a broad sampling of common data formats, a data modification tool, a presentation-quality graphics tool optimized for small-angle scattering data, and a neutron and X-ray scattering contrast calculator. These tools are brought together into a single software suite with consistent interfaces and functionality. The suite allows robust automated user comment recording and saving of parameters during export.

Distribution & Impact

Irena can be freely downloaded as described at the package home page. To run Irena, one must also install the commercial Igor Pro software package, version 6.x. Note that a fully functional 30 day demo version is available from the Wavemetrics web site and is sufficient for testing use of Irena package.

Irena YouTube training video screen shotA manual of over 160 pages is distributed with the software or is available for download from the web site.Instructional movies are available on YouTube.Irena courses, presented by Irena author Jan Ilavsky are presented at the APS and at facilities around the world (list of past courses.) Users are encouraged to register for the mailing list.

The primary Irena reference [Ilavsky, J., & Jemian, P. R. (2009). Irena: tool suite for modeling and analysis of small-angle scattering. Journal of Applied Crystallography, 42(2), 347-353. DOI: 10.1107/s0021889809002222] has been cited over 342 times and there are 218 registered users (both as of February 2015).

Irena is used as the primary support tool package at the APS USAXS instrument (9ID) as well as many other SAXS and SANS instruments around the world.


Funding Source

This project has been produced using operational funding from the APS, contract DE-AC02-06CH11357.


Please cite

Ilavsky, J., & Jemian, P. R. (2009). Irena: tool suite for modeling and analysis of small-angle scattering. Journal of Applied Crystallography, 42(2), 347-353. DOI: 10.1107/s0021889809002222

Irena has grown in size and complexity over the last 15 years and reached mature state, where more additions would make it more difficult to use. Therefore we do not expect major growth and additions. A number of small modifications and improvements are in progress at this time. But since Irena is open source (source code is distributed to users and compiled by Igor Pro locally), users are encouraged to extend the capabilities and contribute them to the community.