SBND Trigger

PMT Channel Mapping for APA 01 Beam left APA
!(/redmine/attachments/download/54604/APA01_PMTMapping.png)

Channel numbers are assigned as shown in the attached images. This information can be accessed in spreadsheet form
here: https://docs.google.com/spreadsheets/d/1kI8WF8RoWlY-Mlga5AjhH72JrFG3PEZWJYm9_y1EvII/edit?usp=sharing
and here: https://docs.google.com/spreadsheets/d/15WJKhYOfIDmWfz2Lb58-w46xkHGvzrhZ_obu3TbIlFw/edit?usp=sharing

PMT Hardware Trigger Simulation

The PMT hardware trigger simulation is a LArSoft producer module that adds in variables indicating if a simulated event would have passed the PMT hardware trigger. The module can be found in sbndcode/Trigger.

Input:

OpDet Waveforms (typically Detsim files will have all these waveforms, reco 1 and 2 files may contain some filtered set of them)

Output:

std::vector<int> numPassed = number of pmt pairs above threshold, index = time during trigger window (usually beam spill)

int maxPMTs = maximum number of pmt pairs above threshold during trigger window (usually beam spill)

Optional: histograms for all included channels of every step of the hardware trigger logic for a configurable set of events

Run the Simulation

    lar -c run_pmttriggerproducer.fcl -s [DetSim root file]

Change the Parameters

The fhicl file can be found in sbndcode/Trigger.

The following parameters can be changed in the fhicl:

OpDetsToPlot: choice to include coated, uncoated, or all PMTs (default = all)

IndividualThresholds: if true, Threshold needs to be a 120 element array of each individual PMT ADC threshold in order of lowest to highest channel number (default = false)

Threshold: PMT threshold, in ADC; format: [coated, uncoated], unless IndividualThresholds is true, (default = [7960, 7976.0] ADC); should be below baseline; simulated baseline = 8000 ADC, ideal single PE response: 1 PE ~ 8 ADC, test bench: 1 PE ~ 25 ADC

OVTHRWidth: over-threshold width (page 40 of hardware trigger manual), controls the number of extra ticks to stay high after a rising edge (trigger goes from 0 to 1) (default = 11)

Pair1: first set of paired PMT channel numbers

Pair2: second set of paired PMT channel numbers

to pair two channels put them at the same index in Pair1 and Pair2
  
i.e. to pair channel 14 and 15 -> Pair1:[x,x,x,14,x,...] and Pair2: [x,x,x,15,x,...]

Unpaired: set of unpaired PMT channel numbers

(default = adjacent channel numbers -> PMTs reflected across x axis, last 8 channels unpaired)

PairLogic: logic for pairing PMTs, options are “OR” or “AND” (default = “OR”)

WindowStart: start time of the trigger window, in us (default = 0.0)

WindowEnd: end time of the trigger window, in us (default = 1.8)

SaveHists: if true, saves the waveform histograms (default = false)

EvHists: if SaveHists=true, which event numbers to save the histograms for (default = [1]); if too many hists are saved, may have memory issues, try saving less events.

Verbose: if true, outputs text about the event (default = false)

Read the Products

The module outputs a pmttriggerproducer product, with object name sbnd::comm::pmtTrigger, that containes the numPassed and maxPMTs variables described above. An example of how to read these can be found in the commisioning hitdumper module (sbndcode/Commissioning/HitDumper_module.cc). Below is the main code from this module.

      art::Handle<std::vector<sbnd::comm::pmtTrigger> > pmtTriggerListHandle;
      std::vector<art::Ptr<sbnd::comm::pmtTrigger> > pmttriggerlist;

    if (evt.getByLabel(fpmtTriggerModuleLabel, pmtTriggerListHandle)){
      art::fill_ptr_vector(pmttriggerlist, pmtTriggerListHandle);
      ResetPmtTriggerVars( (int)pmttriggerlist[0]->numPassed.size());

      for (int i=0; i < (int)pmttriggerlist[0]->numPassed.size(); i++){
        _pmtTrigger_npmtshigh[i] = pmttriggerlist[0]->numPassed[i];
      }
      _pmtTrigger_maxpassed = pmttriggerlist[0]->maxPMTs;
    }

CAEN1730 Fragment Simulation

The PMT fragment producer (sbndcode/Trigger/pmtArtdaqFragmentProducer_module.cc) converts simulated PMT waveforms into CAEN1730 artdaq::Fragment format. For each PMT hardware trigger, waveforms are saved for 5120 samples (~10us, 2ns sampling) from -1us to +9us around the trigger time. Sets of 8 fragments are created per trigger, each containing 15 PMT waveforms + beam signal and timestamps. Trigger time(s) are offset by 0.5 seconds to avoid negative times.

Input:

OpDet Waveforms raw::OpDetWaveform (Detsim stage or later) PMT Hardware trigger output sbnd::comm::pmtTrigger

Output:

CAEN1730 Fragments std::vector<artdaq::Fragment>. Set of 8 fragments are produced for each PMT hardware trigger. Each fragment contains 15 PMT waveforms, 5120 samples (~10us). First fragment of set contains binary beam signal (1 if waveform bin in time with beam, otherwise 0) in 16th channel. Fragment metadata also simulated – fragment ID (0-7), number of channels, waveform length, trigger timestamp.

Run the Simulation

    lar -c run_pmtArtdaqFragmentProducer.fcl -s [PMT hardware trigger root file]

Change the Parameters

The fhicl file can be found in sbndcode/Trigger.

The following parameters can be changed in the fhicl:

InputModuleNameWvfm: input opdet waveforms module name, default “opdaq”

InputModuleNameTrigger: input pmt hardware trigger module name, default “pmttriggerproducer”

Baseline: PMT baseline used when extending/combining waveforms if full 3ms is not simulated, default 8000 ADC

MultiplicityThreshold: PMT-pair multiplicity threshold to pass hardware trigger, default 10 pairs

BeamWindowLength: beam window length, default 1.8 us (extended by 0.2us to account for delayed signals)

Verbose: verbose output for debugging

PMT Software Trigger Simulation

The PMT software trigger producer (sbndcode/Trigger/pmtSoftwareTriggerProducer_module.cc) extracts PMT waveforms from CAEN1730 artdaq::Fragment format, determines which set of fragments is in time with the beam spill, runs desired software trigger metric algorithms and creates sbnd::trigger::pmtSoftwareTrigger object to store results. Filter module(s) can then be run using these metrics.

Metrics available:

Input:

CAEN1730 Fragments std::vector<artdaq::Fragment> created by the fragment simulation producer module.

Output:

PMT software trigger metrics sbnd::trigger::pmtSoftwareTrigger.

The following metrics are contained in the above data product:

foundBeamTrigger: boolean, whether the beam trigger fragment was found

nAboveThreshold: number of total PMTs (# ranges from 0-120) above a ADC threshold (set in fcl) during the beam window (set in fcl, default 1.8 us)

triggerTimestamp: trigger time in ns with respect to the beam spill

promptPE: prompt light; total photoelectron count from all PMTs 100 ns after the triggerTimestamp

prelimPE: preliminiary light; total photoelectron count from all PMTs during the beam spill, before the triggerTimestamp

pmtInfoVec: data product std::vector<sbnd::trigger::pmtInfo> pmtInfoVec;, which contains the channel # for every PMT, baseline info for every PMT, and a vector of pulse information if you run the producer with the pulse algorithm turned on. However, this data product is currently not accessed when reading the metrics in the hitdumpertree.

Run the Simulation

    lar -c run_pmtsoftwaretriggerproducer.fcl -s [PMT fragment simulation root file]

Change the Parameters

The fhicl file can be found in sbndcode/Trigger.

The following parameters can be changed in the fhicl:

is_persistable: controls whether trigger metrics object is written to output root file, default “true”

TriggerTimeOffset: trigger time offset, must match offset used in fragment producer, default 0.5s

BeamWindowLength: beam window length, default 1.8 us (extended by 0.2us to account for delayed signals)

WvfmLength: waveform length, default 5120 samples (could also determine from fragments)

Verbose: verbose output for debugging

SaveHists: boolean, whether or not to save the 10 us waveforms in histograms for the first few events

BaselineAlgo: input a string corresponding to the algorithm for calculating the baseline. Current options: “constant” or “estimate.” If choosing “estimate,” the mean and standard deviation of the first 500 ns (250 entries) of each waveform is calculated. If the standard deviation is above 3 ADC, the mean and stddev of the last 500 ns of each waveform is used instead.

InputBaseline: input baseline for BaselineAlgo: "constant"; default 8000 ADC

InputBaselineSigma: input baseline stddev for BaselineAlgo: "constant; default 2.0 ADC

ADCThreshold: ADC threshold to calculate nAboveThreshold, default 7960 ADC

FindPulses: boolean, whether or not to use the crude pulse finder (more computational); default False

PEArea: Conversion between ADCxns to photoelectrons when using the crude pulse finder