Transcript ppt

Event Context Information: Particle Data
Run Information
Platform, Run ID, TimeStamp
Configuration Information
Hardware and software configuration keys
Datagram information
Bookkeeping of datagrams, mode and status data
“Extended Context Counters” (aka Scalars)
Livetime, elapsed time, event number
Numbers of prescaled, discarded and deadzone events
TimeTone information
GPS, 1-PPS information
Status of GPS, 1-PPS information
Allows to calibrate fluctuations in system clock
Event time
In system clock times
Digitization of the Context
Probably have to store all these data for every event.
About 156 bytes / event uncompressed
Different applications might access only some of these
fields
Probably want to keep the on different ROOT branches
Event Ordering Issues
Events from two streams are interleaved.
Ordering is preserved within a single stream.
To digitize events in order requires having both streams
open at the same time, scanning context record for
timing information
01_EPU0
04_EPU0
00_EPU1
03_EPU1
Time
Timing Issues
Various Pieces of Timing Data
Previous and Current TimeTones in Science stream
Includes GPS seconds since epoch start
TimeHack: 20 MHz and 1-PPS counters
Includes GPS, 1-PPS validity flags
20MHz and 1-PPS counters at most recent time hack, sampled at
event capture time
Hopefully same as values at “Current” TimeTone
20MHz clock sampled at event capture time
Total elapsed and deadtime since run start
Data needed to extract local time
GPS seconds at most recent valid TimeHack
20MHz clock calibrated rate
Number 20MHz ticks since most recent valid tick hack