Instrument Data Acquisition & Controls
The RAD Instrument Data Acquisition and Controls Group supports SNS neutron instruments by designing, building and maintaining custom electronics and software to acquire neutron scattering data from the detector systems; developing software systems for experiment control, automation, data collection and data processing; and developing, optimizing and maintaining the computing and network infrastructure for data acquisition and data analysis, including data storage and user access to data and analysis tools.
The SNS data acquisition system provides a common interface to a variety of detector types, including helium gas detectors and scintillator-based detectors. Custom electronics provide detector read-out and timing data. Data from each of these detector types is processed by a common software package to provide a consistent data format and control sequence independent of the instrument. Data is recorded in "event mode" with each neutron event consisting of a detector pixel identifier, indicating position, and a time of flight, indicating energy. Neutron events are associated with an accelerator pulse that includes a time stamp and the accelerator proton charge on target for that pulse. Neutron data are currently stored in a custom format internal to the data acquisition system during an experiment run and then transferred to another system for generation of data files in a standard NeXus format at the end of the run. Sample environment data are logged internally to the data acquisition system and then transferred at the end of an experiment run, along with the neutron data. Sample data can be correlated with neutron data during the data analysis stage.
The computing infrastructure for access to experiment data and analysis tools includes a load-balanced, high-performance workstation cluster available to SNS users at http://analysis.sns.gov.