Difference between revisions of "Level-3 Trigger Strategy"

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This page will collect the currently planned running times/intensities for GlueX and the expected event rates.  A set of requirements for the Level-3 trigger can be collected based on this information to document the design and implementation strategy.
 
This page will collect the currently planned running times/intensities for GlueX and the expected event rates.  A set of requirements for the Level-3 trigger can be collected based on this information to document the design and implementation strategy.
  
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== Phase IV Planning ==
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== Phase II and III Planning ==
  
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This is the first phase of GlueX running where the Level-3 trigger is required to reduce the even rate beyond the reduction provided in hardware by the Level-1 trigger.  The nominal photon flux in the coherent peak (8.4-9 GeV) for this phase is <math>5 x 10^7</math>, which is expected to result in a Level-1 trigger rate of around 100 kHz based previous studies.  Based on the event size and DAQ bandwidth expectations in Table 2 (below), the event rate to tape is limited to 20 kHz.  Therefore, '''the nominal goal of the Level-3 trigger in Phase IV is to reduce the Level-1 trigger rate by a factor of 5.'''
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After the initial Phase I running period designated for detector commissioning the first "physics" running periods are Phases II and III, which both have a nominal photon flux in the coherent peak (8.4-9 GeV) of <math> 10^7</math>.  The expected Level-1 trigger rate for these periods is expected to be at or below 20 kHz, and therefore it is possible to write the entire dataset to tape with an minimum-bias type L1 trigger.  Therefore, during these running periods the goal is to commission the Level-3 trigger for future running periods by:
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 +
* Run a Level-3 trigger algorithm in pass-through mode on a subset of nodes in the monitoring farm.
 +
* Tag events in the data which satisfy the algorithm requirements to allow studies offline of the:
 +
** Trigger efficiency in the data with full offline reconstruction
 +
** Rate reduction factor
 +
 
 +
== Phase IV Planning ==
  
 +
This is the first phase of GlueX running where the Level-3 trigger is required to reduce the even rate beyond the reduction provided in hardware by the Level-1 trigger.  The nominal photon flux in the coherent peak for this phase is <math>5 x 10^7</math>, which is expected to result in a Level-1 trigger rate of around 100 kHz based previous studies.  Based on the event size and DAQ bandwidth expectations in Table 2 (below), the event rate to tape is limited to 20 kHz.  Therefore, '''the goal of the Level-3 trigger in Phase IV is to reduce the Level-1 trigger rate by a factor of 5 to 20 kHz.'''
  
 
== Assumptions for Level-3 Trigger Planning ==
 
== Assumptions for Level-3 Trigger Planning ==
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| Expected total hadronic event rate (kHz) || ?? || ?? || 36 || 180 || 360
 
| Expected total hadronic event rate (kHz) || ?? || ?? || 36 || 180 || 360
 
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|-  
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| Expected hadronic event rate in coherent peak (kHz) || ?? || ?? || 0.8 || 8 || 16
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| Expected hadronic event rate in coherent peak (kHz) || ?? || ?? || 1.6 || 8 || 16
 
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| Level-1 trigger rate (kHz) || 2 || 20 || 20 || 100 || 200
 
| Level-1 trigger rate (kHz) || 2 || 20 || 20 || 100 || 200

Revision as of 10:15, 19 August 2013

This page will collect the currently planned running times/intensities for GlueX and the expected event rates. A set of requirements for the Level-3 trigger can be collected based on this information to document the design and implementation strategy.

Phase II and III Planning

After the initial Phase I running period designated for detector commissioning the first "physics" running periods are Phases II and III, which both have a nominal photon flux in the coherent peak (8.4-9 GeV) of 10^{7}. The expected Level-1 trigger rate for these periods is expected to be at or below 20 kHz, and therefore it is possible to write the entire dataset to tape with an minimum-bias type L1 trigger. Therefore, during these running periods the goal is to commission the Level-3 trigger for future running periods by:

  • Run a Level-3 trigger algorithm in pass-through mode on a subset of nodes in the monitoring farm.
  • Tag events in the data which satisfy the algorithm requirements to allow studies offline of the:
    • Trigger efficiency in the data with full offline reconstruction
    • Rate reduction factor

Phase IV Planning

This is the first phase of GlueX running where the Level-3 trigger is required to reduce the even rate beyond the reduction provided in hardware by the Level-1 trigger. The nominal photon flux in the coherent peak for this phase is 5x10^{7}, which is expected to result in a Level-1 trigger rate of around 100 kHz based previous studies. Based on the event size and DAQ bandwidth expectations in Table 2 (below), the event rate to tape is limited to 20 kHz. Therefore, the goal of the Level-3 trigger in Phase IV is to reduce the Level-1 trigger rate by a factor of 5 to 20 kHz.

Assumptions for Level-3 Trigger Planning

Some assumptions are necessary to plan for the requirements of the Level-3 trigger based on the expected running conditions of the experiment. Below are two tables with some assumptions for the data taking conditions for the GlueX experiment.

Table 1: Planned GlueX Running Periods (from PAC 40 Proposal)
Phase I Phase II Phase III Phase IV Maximum Intensity
Approved PAC days 30 30 60 200 0
Minimum electron energy (GeV) 10 11 12 12 12
Photon flux in coherent peak (photon/s) 10^{6} 10^{7} 10^{7} 5x10^{7} 10^{8}
Expected total hadronic event rate (kHz)  ??  ?? 36 180 360
Expected hadronic event rate in coherent peak (kHz)  ??  ?? 1.6 8 16
Level-1 trigger rate (kHz) 2 20 20 100 200


Table 2: Data rate assumptions for GlueX
Event size 15 kB
DAQ bandwidth to write events to tape 300 MB/s
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