The Advanced Photon Source
a U.S. Department of Energy Office of Science User Facility

Beamline Controls and Data Handling

Beamline Controls and Data Acquisition

Beamline controls operate through EPICS, with the standard caQtDM graphical interface.

For time resolved radiography and focused-beam fluorescence, scan controls are typically provided by the EPICS scan record.

For high-speed imaging, control of the camera is typically performed with the camera vendor's software.  

For tomography measurements, data acquisition is controlled with custom Python scripts.

When needed, Python is used for scripting, based on the PyEpics implementation written by CARS. The beamline workstation has access to the Anaconda Python distribution, which includes many common Python packages, such as numpy, scipy, h5py, and others.

Data Formats

Time resolved data collected at the beamline are typically stored in a locally-defined binary data file. For distribution to users, these files are converted to HDF5, a widely used, hierarchical binary data format that can be accessed using tools in a wide variety of programming languages. Other formats can potentially be accommodated upon request; please contact beamline staff prior to your beamtime if a different format is needed.

Data collected at the beamline using the standard EPICS scan record (typically time-averaged data) are saved in an APS-specific binary format based on the Sun Microsystems XDR data format (described more fully here). Tools exist to visualize data while on-site. To make these data readable to outside users, the data can be converted either to ASCII text or to HDF5 binary format.

Tomography data are stored in Data Exchange format.  This allows for the data to be easily read and analyzed.  Tomography reconstructions are performed using TomoPy, an open-source library for tomography reconstructions.  It features a wide range of data preparation tools and reconstruction algorithms, including both CPU- and GPU-based methods. 

Moving Data from APS

To facilitate users returning their data to their home institution, two main methods are available.  For relatively small amounts of data (less than several GB), data can be shared through Box, a cloud data storage provider.  Data are uploaded to a Box folder and users are given a link to download their data.

For larger datasets, Globus, a GridFTP solution, is used.  Data are uploaded to a folder on Voyager, the APS data storage facility.  Permissions are then given to individual users to download data from Voyager.  Instructions will be given to users as needed on how to access Voyager.

Data Retention Policy

While the beamline will store users' data temporarily, the ultimate responsibility for data retention lies with users. For time-averaged point detector data, the beamline will store users' data on APS servers for a minimum of two years. For time-resolved point detector data and all area detector data, including tomography, the beamline will store user's data on APS servers for a minimum of one year.

 

01.20.2020