Fitting auto-reduced data

This page describes the steps one takes when fitting 1D reflectivity data on the web application, starting when looking at the auto-reduced data for a particular run in the web monitor app.

Once at the web monitor, go to the page of a run that was auto-reduced, e.g.: https://monitor.sns.gov/report/ref_l/191809/

Above the plot, there’s a link to the fitting application. Click it: https://reflectivity.sns.gov/fit/ref_l/191809

You should now see the same data. The data that was shown on the web monitor is also shown on the reflectivity fitting application.

In the Layer model section, you will now be able to define a model and perform a fit. In the layer that’s called material, try entering a thickness of 725 Å and an SLD of 6.3. The uncheck the boxes for that layers thickness, SLD, and roughness. Also uncheck the Si roughness. Fitting parameters will now appears at the bottom of the page. Enter a maximum value of 1000 for the thickness, 10 for the SLD, and 15 for the roughness parameters. Then click fit.

After a few seconds a message will appear to let you know the fit is done. Click that link:

Fit graph and optimal parameters should look like this: