Readout of the Trigger Subsystems
..... very preliminary! .....
Just like any subdetector every trigger subsystem provides a data record, which is read out by DAQ in case of a level-1 accept.
Data from bunch crossings preceding or following the one for which a level-1 accept was issued by the Global Trigger may also
be read out.
This is the generic data format prescribed by DAQ:
K: Control bit to identify header or trailer
D: Data bit to identify subdetector payload
Evt_ty: Event type, sometimes also called trigger type
FOV: Format version
Hx: bit to include more header words if desired (if H='1', last header word; if H='0' one header word follows)
Evt_ty: Event type (4 bits) - to be agreed upon
Evt_lgth: Event length expressed in 64-bit words
CRC: Cyclic redundancy code (16 bits) to detect data transmission errors- algorithm decided in Dec. 2002
Evt_stat: Event status (8 bits) - to be agreed upon
Current collection of information to be stored by each trigger subsystem:
Global Calorimeter Trigger: includes data from ECAL TPGs and Regional Calorimeter Trigger
DT Local Trigger
DT Track Finder (DT Regional Trigger)
CSC Local Trigger
CSC Track Finder (CSC Regional Trigger): short writeup (.ps), long documentation (.doc)
RPC Trigger: RPC input/output data are sent to DAQ via RPC detector path. Compression algorithm for raw data can be found here.
Open questions:
How can different debug levels be obtained? - Most likely in subdetector payload, not in event type ...
Suggested common rules for trigger subsystems:
To be done ...
It is obvious that identical quantities such as GPS time, orbit number etc. should be in the same place across trigger subsystems.
Final bit by bit event format for each trigger subsytem:
To be done ...
This page is maintained by Claudia-Elisabeth
Wulz
Last update: February 2003