NCNR Reflectometry Software

NCNR has a number of programs to aid in reflectometry.

Experiment Design

Given your sample structure you can calculate what sort of reflectivity curve you expect to see. To do this you need to compute the scattering length densities in your sample from basic principles using the atomic properties of your sample, or you can calculate them from the chemical formula. Similar calculations are available in the excel spreadsheet nbcu.xls. Given the scattering length densities, you can generate a layer profile from which you can calculate the expected reflectivity. The reflectivity can be calculated with a java applet, or using the data analysis software mentioned below.

Collecting data

Instruments are controlled using ICP. With the appropriate choice of parameters, you can generate specular, background and rocking curves. While you are collecting data you will need xpeek to view the data. This is available on all the instrument computers.

Data Reduction and Analysis

For data reduction there is reflred. It allows you to view raw X-Ray, NG-1 and NG-7 data files and reduce them to a reflectivity curve. It does not yet support polarized data for NG-1 completely. See your instrument contact for additional software.

For analysis there is the layer-based reflfit and reflpol programs, and the spline-based PBS. reflpol fits data from polarized neutrons. There is also a mathematica notebook for performing direct inversion which you can sometimes apply.

We are actively improving the usability of our software, but it is not yet complete enough along that you can use it without further instruction. Preliminary manuals are available for reflred and reflfit/reflpol and via the F1 key within the programs. Please see your instrument contact for more information.

Reflred, reflfit and reflpol can be used off site. Source and precompiled versions for IRIX, OS X, Windows and Linux are available for the current version as well as older versions.

Reflfit and reflpol are being combined and extended to support simultaneous fitting. The program GA refl is an intermediate stage in this process. It supports simultaneous fitting of X ray and neutron data, but lacks an easy to use interface.

A preliminary version of the composite modelling program KSrefl is available, including a brief manual (pdf). This is pre-alpha software; use at your own risk.

Citing reflfit, reflpol, reflred

Acknowledging use of reflpak in publications may be done by making a reference to this site. For example:

The programs from the reflpak suite were used for elements of the data reduction and analysis.[1]

[1] P.A. Kienzle, K.V. O'Donovan, J.F. Ankner, N.F. Berk, C.F. Majkrzak; http://www.ncnr.nist.gov/reflpak. 2000-2006

Disclaimer

This software was developed at the National Institute of Standards and Technology at the NIST Center for Neutron Research by employees of the Federal Government in the course of their official duties. Pursuant to title 17 section 105* of the United States Code this software is not subject to copyright protection and is in the public domain. NIST does not assume any responsibility whatsoever for the use of this software, and makes no guarantees, expressed or implied, about its quality, reliability, or any other characteristic. The use of certain trade names or commercial products does not imply any endorsement of a particular product, nor does it imply that the named product is necessarily the best product for the stated purpose. We would appreciate acknowledgment if the software is used.

*Subject matter of copyright: United States Government works

Copyright protection under this title is not available for any work of the United States Government, but the United States Government is not precluded from receiving and holding copyrights transferred to it by assignment, bequest, or otherwise.

Acknowledgments

Portions of this work are based upon activities supported by the National Science Foundation under Agreement No. DMR-0412074.

References

Calculating polarized neutron reflectometry

C.F. Majrkzak, K.V. O'Donovan, N.F. Berk (2006); Polarized neutron reflectometry. In Neutron Scattering from Magnetic Materials, T. Chatterji, editor. Elsevier.

Polarization corrections

C.F. Majkrzak (1996); Neutron scattering studies of magnetic thin films and multilayers, Physica B 221, 342-356.

Modelling interfaces with slabs

J.F. Ankner, C.F. Majkrzak (1992); Subsurface profile refinement for neutron specular reflectivity. In S.P.I.E. Conference Proceedings, Vol. 1738. C.F. Majkrzak and J.L. Wood, editors. S.P.I.E., Bellingham, WA.

Last modified 28-June-2006