`filewriter`: Neutron event data (`raw_data_1/detector_1_events`)

Bắt đầu từ entry point của filewriter và so sánh đầu ra hiện có của nó với nhóm NXevent_data trong raw_data_1/detector_1_events. Đọc behavior của event_aggregator và giải quyết các câu hỏi về event_time_bins, thứ tự thời gian tham chiếu, thứ tự event và các cờ veto. Công việc được xem là hoàn tất khi format tệp event streaming bắt buộc và các quy tắc xử lý đã được thống nhất và triển khai.

The filewriter must be able to write out event-mode data.

This means the contents of the NXevent_data group in raw_data_1/detector_1_events

Questions

• What do we want to do with event_time_bins, which aren't meaningful in streaming system?
• Due to an underlying UDP connection from hardware, the streaming system cannot guarantee that frame N+1 will have a later reference_time than frame N. Do any consumers make assumptions about this?
  • This affects whether we can stream events to file directly, or whether we have to buffer, sort by reference time, and then write to file
• Does mantid have a dependency on event time-of-flights being ordered within a frame? Currently this sort is (optionally) done at event_aggregator level as multiple consumers benefit from improved performance with sorted events.

Potential differences from existing files

• We likely no longer need to apply a random event_time_offset_shift, as the new electronics has a much higher time resolution than the old DAE electronics. See https://github.com/ISISComputingGroup/DataStreaming/issues/22 .
• We want to be able to write the veto flags for each frame alongside the event data, to enable downstream consumers to retroactively enable or disable a veto if it chooses:
  • active_vetos: the veto signals that were actually active for a given frame
  • enabled_vetos: the vetoes that were enabled in IBEX at the time of data acquisition
  • By default downstream consumers will want to mask any events where active_vetos & enabled_vetos != 0.
  • If adding this logic is problematic for Mantid, we could (optionally) drop the frames at filewriter level instead - at the cost of reducing flexibility and reducing diagnostics we have access to.