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EVIO Data Format

Overview

EVIO (Event IO) is the raw data format used by the DAQ event builder.  The structure of an EVIO file is a tree of banks, each of which has a header and a data payload. 

EVIO Data Types

Each EVIO bank has a data type a tag and a num. The type corresponds to the contents of the bank. 

data_typeSizecontentnotes
0x0c,0x0d,0x0e,0x10,0x20,0x40Ncontainerthis is a bank that contains other banks
0x00, 0x014uint32_tunsigned integers
0x024float 
0x0b4intsigned integers
0x0fNcompound typeFADC (or other!) compound format.
0x031charchar
0x061int8_t = charchar
0x071uint8_tunsigned char
0x042int16_tshort
0x052uint16_tunsigned short
0x088double 
0x098int64_tlong
0x0a8uint64_tunsigned long

Source: EVIO C++ code data parser.
Note: The 0x0f compound type data contains a string that tells you what the layout of the data is. See EVIO documentation. 

On the CLON machines, in the directory pointed to by $CLON_PARMS, is the file "clonbanks.xml", which contains the "dictionary" for the EVIO contents of various bank tags used in the data.

EVIO Event types - 2015 Data Set

The very top bank in an event tree is usually a container bank (0x10). The "tag" of this bank indicates the event type. The event types used for the 2015 data set of HPS are listed below. Note that this is set by the DAQ configuration and is thus subject to change. Currently 16 - 32 are special event types, all others are "Physics" events. For physics events, the number is a bit encoded state of the trigger, with the high bit, bit 7, set. Thus physics events start at 128 and go up. The bit 6 encodes a "sync" event, which will contain scalers. 

Event type #NameNotes
17Pre StartIndicates the "pre-start" transition in the DAQ
18GoIndicates the user pressed "Go" on DAQ
19PauseIndicates the user pressed "Pause" on DAQ
20EndEnd of run marker event.
31EpicsEpics event - Slow controls data that is injected into the data stream.
Bit 7PhysicsPhysics events should have bit 7 set
Bit 6SyncSync events (containing scalers and trigger config) should have bit 6 set.
This was not working properly before 2015_03_24 
Bit 5PulserThe pulser triggered the event.
Bit 4LED/CosmicLED or Cosmic trigger.
Bit 3Pairs 1Indicates a Pair1 trigger.
Bit 2Pairs 0Indicates a Pair0 trigger.
Bit 1Single 1Indicates a Single1 trigger.
Bit 0Single 0Indicates a Single0 trigger.

 

Below is a list of the banks and tags used in the 2015 Engineering Run for HPS. Note that the bank numbers and tags used are chosen by the DAQ configuration, and are thus subject to change. 

banktagNameNotes
    
    
    

 

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