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EVB (Assembler)

The Event Builder, or the Assembler PC is the DAQ server that receives data from all the SEBs, creates a full event out of it and writes it to local disk.

Fragments from all SEBs are collected and stored in the Event Store. Each fragment has a fragment ID specifying the SEB it came from and a sequence ID specifying the event number.

Once all the fragments for a specific sequence ID are in the Event Store, the fragment collection is transferred to queue to be handled by the EventBuilder, where:
  • Global headers and more information is add
  • A software trigger is applied
  • The event is written to disk
  • In case maximal number of events per file has been reached, subrun information will be written as well.