Ultra-Small-Angle X-ray Scattering Facility

Data management

This page summarizes USAXS data management policies

USAXS follows requirements stated in the official APS data management policies. There are, however, instrument related specifics which are summarized on this page.

Anything listed on this page relates ONLY to data from USAXS/SAXS/WAXS instrument.

Data retention policy

Data are retained (per APS data retention policy) by beamline staff for period of at least 3 months. Generally you can expect to be able to request data from staff for a year and possibly beyond (ask), but we guarantee only 3 months. Make backup! 

In order to recover your data, you need to provide us with user name for which the data were collected and dates when the data were collected. And ideally also at least some names of samples which were measured. 

Data accessibility

Data ownership varies and is governed by user agreement. Note, that there are no safeguards preventing other instrument users from viewing the data stored at the beamline. Also, during limited time after data are collected, partially reduced data are visualized by our on-line system which is viewable world-wide using live data page

Data can be copied by users at the beamline on USB storage media.  Typically users produce less than 1Gb of data per day. If necessary, staff will provide users with limited time access to on-line storage (box.com is ANL prefered method) so they can download their data. No other method of access to data is supported. 

Users (and not APS or the USAXS instrument!) are long term custodians of data and are responsible for making data available to the community, if appropriate and needed. Users are also solely responsible for providing suitable sample metadata and other information needed for community use. 

Type of data automatically collected (metadata)

We collect only limited user provided information about the samples - typically sample name and thickness - needed for data reduction. However, large amount of instrument and data collection related data ("metadata") is collected with each scan, including complete instrument calibration, etc. All user data and metadata are stored in Nexus data files generated by the instrument and provided to users. We use NXsas and NXcanSAS file formats as appropriate. While we attempt to store as much automatically generated metadata as we can, we cannot guarantee a specific type of metadata is included, unless user specifically requests such metadata to be stored before experiment starts. It is the duty of the user to understand which metadata are/will be needed for his/her project and inform about it the staff BEFORE start of experiment

If you need to extract specific metadata from USAXS/SAXS/WAXS Nexus files, contact staff to provide information where the metadata can be found. Number of general purpose tools (including Python tools) can read hdf5 files used by Nexus and extract needed information. Free and easy to get to viewer for HDF files is HDFview

Data reduction tools

USAXS/SAXS/WAXS uses packages Indra, Nika, and Irena; all maintained by staff and freely available for download. These packages, however, use commercial software Igor Pro (Wavemetrics Inc.). Igor Pro demo version can be used for data reduction and analysis during its 30 day full feature demo period. For more details see Software page.