Neutron scattering is an integral part of scientific research as it enables the measurement of materials properties by studying the interaction of neutrons with the nuclei of atoms in materials. One prominent scattering technique is neutron reflectometry, which is routinely used to non- destructively measure the depth profile of thin film materials. Unfortunately, these measurements are complicated, and interpretation can be challenging as complex mathematical modeling is required to correlate the data to meaningful metrics. Despite the criticality of this modeling, the relative rarity of neutron sources has hindered the maturation of modeling software packages used to interpret neutron data. While powerful, current modeling software suffers from a lack of mature graphic user interface and other User Interface/User Experience tools that would make it more accessible to both neutron scientists at large and the broader scientific community. While the value of modern modeling tools cannot be understated, a lack of a mature, usable interface and installation package means many users find it difficult if not impossible to utilize without prior knowledge of setting up a software environment or utilizing a command line interface. In this SBIR Phase I, a robust open-source graphical user interface will be developed in the Python programming language around the Refl1D base code. This user interface will be designed to streamline the modeling process, while clearly exposing all the tools and features the software has to offer. The package will also include in-software documentation that will lead users through the tool sets available. Once developed, it will be packaged for use with Windows, Mac, and Linux platforms, further extending the accessibility of the software and increasing the chances of widespread user adoption. The single-click installer will eliminate the need for users to configure their Python interpreter and libraries to conform to the needs of Refl1D. Finally, the application will be hosted on an open source platform in order to enable quick accessibility and user feedback. One of the primary focuses of this work is to emphasize the features that are of most value to the neutron reflectometry user. First, a data reduction panel will be developed so that users can import, aggregate, process, and normalize the data. Once the data is reduced, it can be modeled in a "model development" panel. This panel will provide several features critical to data analysis, including model building, fit parameter development, fit method selection and local/remote processing. The panel will then provide real-time feedback to the user as the modeling process is carried out. In a subsequent SBIR Phase II, the base functionality of Refl1D will be expanded with the integrated of other reflectometry tools into the main software package. This will provide users with a "one stop shop" for all their data processing and modeling needs, and significantly reduce scientists' time and efforts between data acquisition and publication.
