## 4 Results
### Event Data Mode and New Features Related to Live Displays  
One of the results of this upgrade is that it enables the production of event mode data for the whole DAS, especially the detectors at HFIR. Event mode imposes timestamps on neutron events detected and on other instrument systems, such as fast sample environment devices, enabling convenient post-data collection filtering. This is very useful in experiments that involve time-resolved kinetic studies, stroboscopic methods, setting up a time-of-flight source at HFIR with choppers, or simply detecting sample deterioration over time. At SNS, \"event mode\" refers to the pulsed accelerator timing signal; however, as a continuous neutron source, HFIR did not have an inherent timing signal as a reference. Therefore, a time server was set up for HFIR instruments; and Network Time Protocol [19] is used to synchronously timestamp events at an instrument, including neutron events and fast sample environment data, at a precision of within 1 ms. The system was made compatible with SNS event-based acquisition, which uses a timestamping rollover of 16.6667 ms, corresponding to the 60 Hz pulse rate. In other words, the events are grouped by their occurrence in the 16.6667 ms windows, and as such are saved in data files in Nexus format. For reactor-based instruments such as Bio-SANS and GP-SANS, the event timestamps are merely additional information about the neutron events and can be ignored if only the histogram of the data is used. No other changes or additions at HFIR SANS instruments are needed for event-based acquisition, as the relevant features had already been developed and tested on the SNS instruments. In Figure 10, an example of event mode data shows the rapid precipitation that occurs in a novel high strength, high ductility alloy that occurs as the sample was heated from room temperature to 700 \({}^{\circ}\)C from an experiment on GP-SANS [20]. The size and number density of the precipitates mediates the balance between strength and ductility in this family of alloys. The SANS data can detect such precipitates in-situ. This data was collected in the event mode in a single data set and was processed post-experimentally to split it up by 60-s interval during the temperature ramp and ten 300-s intervals for the annealing temperature. Moreover, the post-experiment process can be flexible depending on samples and sample conditions. The new capability also allows the visualization of sequential defined-time snapshots of the event mode data to aid real-time experimental evaluation and planning.  
We have been using EPICS area detector driver for neutron event data (ADnED) and dynamicMapping (a Python tool for live data conversions) [9] to provide meaningful 2D and 1D live displays on other instruments. There are three related new features on SANS that may be worth mentioning. First, an ImageSnapshot Python tool has been deployed on the SANS instruments (and a few other instruments), which saves snapshots of histogrammed 2D detector images at the end of a run. These images are further parsed and ingested in the data catalog database for a quick view of measurement data. They can also be used for quick data reduction without reading the large HDF5 files if event mode data is not needed. Second, by updating dynamicMapping and saving and reusing beam center information in Q-range configurations, we were able to fully automate dynamicMapping to update mapping files for live d-spacing and Q conversions and for cursor display on the histogrammed 2D detector images. Third, a prototype Python tool, SANS-AutoRebin, has been developed to bin the data integrated by ADnED into log bins using default Q-range configurations, normalize log-binned data according to the number of pixels contributing to each log bin, and then scale the normalized data to beam monitor counts or run time. This prototype tool is part of our effort to provide users with live, coarsely reduced data for better steering of their experiments during the run time.