ecal::EcalDigiProducer Class Reference

Performs basic ECal digitization. More...

#include <EcalDigiProducer.h>

Public Member Functions
	EcalDigiProducer (const std::string &name, framework::Process &process)
	Constructor.
virtual	~EcalDigiProducer ()=default
	Destructor.
virtual void	configure (framework::config::Parameters &) override
	Configure this producer from the python configuration.
virtual void	produce (framework::Event &event) override
	Simulates measurement of pulse and creates digi collection for input event.
virtual void	onNewRun (const ldmx::RunHeader &runHeader) override
	Set up random number / noise generation.
Public Member Functions inherited from framework::Producer
	Producer (const std::string &name, Process &process)
	Class constructor.
virtual void	process (Event &event) final
	Processing an event for a Producer is calling produce.
Public Member Functions inherited from framework::EventProcessor
	DECLARE_FACTORY (EventProcessor, EventProcessor *, const std::string &, Process &)
	declare that we have a factory for this class
	EventProcessor (const std::string &name, Process &process)
	Class constructor.
virtual	~EventProcessor ()=default
	Class destructor.
virtual void	beforeNewRun (ldmx::RunHeader &run_header)
	Callback for Producers to add parameters to the run header before conditions are initialized.
virtual void	onFileOpen (EventFile &event_file)
	Callback for the EventProcessor to take any necessary action when a new event input ROOT file is opened.
virtual void	onFileClose (EventFile &event_file)
	Callback for the EventProcessor to take any necessary action when a event input ROOT file is closed.
virtual void	onProcessStart ()
	Callback for the EventProcessor to take any necessary action when the processing of events starts, such as creating histograms.
virtual void	onProcessEnd ()
	Callback for the EventProcessor to take any necessary action when the processing of events finishes, such as calculating job-summary quantities.
template<class T >
const T &	getCondition (const std::string &condition_name)
	Access a conditions object for the current event.
TDirectory *	getHistoDirectory ()
	Access/create a directory in the histogram file for this event processor to create histograms and analysis tuples.
void	setStorageHint (framework::StorageControl::Hint hint)
	Mark the current event as having the given storage control hint from this module_.
void	setStorageHint (framework::StorageControl::Hint hint, const std::string &purposeString)
	Mark the current event as having the given storage control hint from this module and the given purpose string.
int	getLogFrequency () const
	Get the current logging frequency from the process.
int	getRunNumber () const
	Get the run number from the process.
std::string	getName () const
	Get the processor name.
void	createHistograms (const std::vector< framework::config::Parameters > &histos)
	Internal function which is used to create histograms passed from the python configuration @parma histos vector of Parameters that configure histograms to create.

Private Attributes
std::string	input_coll_name_
	input hit collection name
std::string	input_pass_name_
	input pass name
std::string	digi_coll_name_
	output hit collection name
double	clock_cycle_
	Time interval for chip clock in ns.
int	n_adcs_
	Depth of ADC buffer.
int	i_soi_
	Index for the Sample Of Interest in the list of digi samples.
double	mev_
	Conversion from energy in MeV to voltage in mV.
bool	zero_suppression_
	When emulating noise in empty channels, do we zero suppress?
bool	noise_ {true}
	Put noise into empty channels, not configurable, only helpful in development.
std::unique_ptr< ldmx::HgcrocEmulator >	hgcroc_
	Hgcroc Emulator to digitize analog voltage signals.
double	ns_
	Conversion from time in ns to ticks of the internal clock.
double	readout_threshold_
	Read out threshold.
double	pedestal_
	Read out pedestal.
double	noise_rms_
	Noise RMS.
std::unique_ptr< ldmx::NoiseGenerator >	noise_generator_
	Generates noise hits based off of number of cells that are not hit.
std::mt19937	rng_
	Generates random numbers for which channels to fill up with noise.

Additional Inherited Members
Protected Member Functions inherited from framework::EventProcessor
void	abortEvent ()
	Abort the event immediately.
Protected Attributes inherited from framework::EventProcessor
HistogramPool	histograms_
	helper object for making and filling histograms
NtupleManager &	ntuple_ {NtupleManager::getInstance()}
	Manager for any ntuples.
logging::logger	the_log_
	The logger for this EventProcessor.

Detailed Description

Performs basic ECal digitization.

Definition at line 33 of file EcalDigiProducer.h.

Constructor & Destructor Documentation

EcalDigiProducer()

ecal::EcalDigiProducer::EcalDigiProducer ( const std::string & name, framework::Process & process )

inline

Constructor.

Definition at line 38 of file EcalDigiProducer.h.

      : Producer(name, process) {}

Member Function Documentation

configure()

void ecal::EcalDigiProducer::configure ( framework::config::Parameters & ps )

overridevirtual

Configure this producer from the python configuration.

Sets event constants and configures the noise generator, noise injector, and pulse function. Creates digi collection

Reimplemented from framework::EventProcessor.

Definition at line 21 of file EcalDigiProducer.cxx.

                                                              {
  // settings of readout chip
  //  used  in actual digitization
  auto hgcroc_params = ps.get<framework::config::Parameters>("hgcroc");
  hgcroc_ = std::make_unique<ldmx::HgcrocEmulator>(hgcroc_params);
  clock_cycle_ = hgcroc_params.get<double>("clock_cycle");
  n_adcs_ = hgcroc_params.get<int>("n_adcs");
  i_soi_ = hgcroc_params.get<int>("i_soi");
  noise_ = hgcroc_params.get<bool>("noise");
 
  // collection names
  input_coll_name_ = ps.get<std::string>("input_coll_name");
  input_pass_name_ = ps.get<std::string>("input_pass_name");
  digi_coll_name_ = ps.get<std::string>("digi_coll_name");
 
  zero_suppression_ = ps.get<bool>("zero_suppression");
 
  // physical constants
  //  used to calculate unit conversions
  mev_ = ps.get<double>("mev");
 
  // Time -> clock counts conversion
  //  time [ns] * ( 2^10 / max time in ns ) = clock counts
  ns_ = 1024. / clock_cycle_;
 
  readout_threshold_ = ps.get<double>("avg_readout_threshold");
  pedestal_ = ps.get<double>("avg_pedestal");
  noise_rms_ = ps.get<double>("avg_noise_rms");
}

References clock_cycle_, digi_coll_name_, framework::config::Parameters::get(), hgcroc_, i_soi_, input_coll_name_, input_pass_name_, mev_, n_adcs_, noise_, noise_rms_, ns_, pedestal_, readout_threshold_, and zero_suppression_.

onNewRun()

void ecal::EcalDigiProducer::onNewRun ( const ldmx::RunHeader & runHeader )

overridevirtual

Set up random number / noise generation.

Reimplemented from framework::EventProcessor.

Definition at line 51 of file EcalDigiProducer.cxx.

                                                    {
  // noise generator by default uses a Gausian model for noise
  //  i.e. It assumes the noise is distributed around a mean (setPedestal)
  //  with a certain RMS (setNoise) and then calculates
  //  how many hits_ should be generated for a given number of empty
  //  channels and a minimum readout value (setNoiseThreshold)
  noise_generator_ = std::make_unique<ldmx::NoiseGenerator>();
  // Configure generator that will produce noise hits_ in empty channels
  // rms noise in mV
  noise_generator_->setNoise(noise_rms_);
  // mean noise amplitude (if using Gaussian Model for the noise) in mV
  noise_generator_->setPedestal(pedestal_);
  // threshold for readout in mV
  noise_generator_->setNoiseThreshold(readout_threshold_);
  // Set up seeds
  const auto& rseed = getCondition<framework::RandomNumberSeedService>(
      framework::RandomNumberSeedService::CONDITIONS_OBJECT_NAME);
  noise_generator_->seedGenerator(
      rseed.getSeed("EcalDigiProducer::NoiseGenerator"));
  // Random number generator for layer_ / module_ / cell
  rng_.seed(rseed.getSeed("EcalDigiProducer"));
  // Setting up the read-out chip
  hgcroc_->seedGenerator(rseed.getSeed("EcalDigiProducer::HgcrocEmulator"));
  hgcroc_->condition(
      getCondition<conditions::DoubleTableCondition>("EcalHgcrocConditions"));
}

References framework::RandomNumberSeedService::CONDITIONS_OBJECT_NAME, framework::EventProcessor::getCondition(), hgcroc_, noise_generator_, noise_rms_, pedestal_, readout_threshold_, and rng_.

produce()

void ecal::EcalDigiProducer::produce ( framework::Event & event )

overridevirtual

Simulates measurement of pulse and creates digi collection for input event.

HACK ALERT The shifting of the time should not be done this sloppily. In reality, each chip has a set time phase that it samples at (relative to target), so the time shifting should be at the emulator level.

Implements framework::Producer.

Definition at line 78 of file EcalDigiProducer.cxx.

                                                    {
  // Empty collection to be filled
  ldmx::HgcrocDigiCollection ecal_digis;
  ecal_digis.setNumSamplesPerDigi(n_adcs_);
  ecal_digis.setSampleOfInterestIndex(i_soi_);
 
  // detector IDs that already have a hit in them
  std::set<unsigned int> filled_det_i_ds;
 
  /******************************************************************************************
   * HGCROC Emulation on Simulated Hits
   *****************************************************************************************/
  // std::cout << "Sim Hits" << std::endl;
  // get simulated ecal hits_ from Geant4
  //  the class EcalHitIO in the SimApplication module_ handles the translation
  //  from G4CalorimeterHits to SimCalorimeterHits this class ensures that only
  //  one SimCalorimeterHit is generated per cell, but multiple "contributions"
  //  are still handled within SimCalorimeterHit
  auto ecal_sim_hits{event.getCollection<ldmx::SimCalorimeterHit>(
      input_coll_name_, input_pass_name_)};
 
  /* debug printout
  std::cout << "Energy to Voltage Conversion: " << mev_ << " mV/MeV" <<
  std::endl;
   */
 
  for (auto const& sim_hit : ecal_sim_hits) {
    std::vector<std::pair<double, double>> pulses_at_chip;
    for (int i_contrib = 0; i_contrib < sim_hit.getNumberOfContribs();
         i_contrib++) {
      /* debug printout
      std::cout << simHit.getContrib(iContrib).edep << " MeV" << std::endl;
       */
      pulses_at_chip.emplace_back(
          sim_hit.getContrib(i_contrib).edep_ * mev_,
          sim_hit.getContrib(i_contrib).time_  // global time (t=0ns at target)
              - sim_hit.getPosition().at(2) /
                    299.702547  // shift light-speed particle traveling along z_
      );
    }
 
    unsigned int hit_id = sim_hit.getID();
    filled_det_i_ds.insert(hit_id);
 
    ldmx_log(debug) << " Emulation of hitID = " << hit_id
                    << " with energy = " << sim_hit.getEdep()
                    << " MeV at time = "
                    << sim_hit.getTime() -
                           sim_hit.getPosition().at(2) / 299.702547;
 
    // container emulator uses to write out samples and
    // transfer samples into the digi collection
    std::vector<ldmx::HgcrocDigiCollection::Sample> digi_to_add;
    if (hgcroc_->digitize(hit_id, pulses_at_chip, digi_to_add)) {
      ldmx_log(debug) << "  --> The HGCROC will read-out this hit!";
      ecal_digis.addDigi(hit_id, digi_to_add);
    }
  }
 
  /******************************************************************************************
   * Noise Simulation on Empty Channels
   *****************************************************************************************/
  if (noise_) {
    // put noise into some empty channels
 
    // geometry constants
    //  These are used in the noise generation so that we can randomly
    //  distribute the noise uniformly throughout the ECal channels.
    const auto& geom = getCondition<ldmx::EcalGeometry>(
        ldmx::EcalGeometry::CONDITIONS_OBJECT_NAME);
    int n_ecal_layers = geom.getNumLayers();
    int n_modules_per_layer = geom.getNumModulesPerLayer();
    int n_cells_per_module = geom.getNumCellsPerModule();
    int num_empty_channels =
        n_ecal_layers * n_modules_per_layer * n_cells_per_module -
        ecal_digis.getNumDigis();
 
    // Uniform distributions for integer generation
    std::uniform_int_distribution<int> layer_dist(0, n_ecal_layers - 1);
    std::uniform_int_distribution<int> module_dist(0, n_modules_per_layer - 1);
    std::uniform_int_distribution<int> cell_dist(0, n_cells_per_module - 1);
 
    if (zero_suppression_) {
      // noise generator gives us a list of noise amplitudes [mV] that randomly
      // populate the empty channels and are above the readout threshold
      auto noise_hit_amplitudes{
          noise_generator_->generateNoiseHits(num_empty_channels)};
      std::vector<std::pair<double, double>> fake_pulse(1, {0., 0.});
      for (double noise_hit : noise_hit_amplitudes) {
        // generate detector ID for noise hit
        // making sure that it is in an empty channel
        unsigned int noise_id;
        do {
          int layer_id = layer_dist(rng_);
          int module_id = module_dist(rng_);
          int cell_id = cell_dist(rng_);
          auto det_id = ldmx::EcalID(layer_id, module_id, cell_id);
          noise_id = det_id.raw();
        } while (filled_det_i_ds.find(noise_id) != filled_det_i_ds.end());
        filled_det_i_ds.insert(noise_id);
 
        // noise generator gives the amplitude above the readout threshold
        //  we need to convert it to the amplitude above the pedestal
        noise_hit +=
            hgcroc_->gain(noise_id) *
            (hgcroc_->readoutThreshold(noise_id) - hgcroc_->pedestal(noise_id));
 
        // create a digi as put it into the collection
        ecal_digis.addDigi(noise_id, hgcroc_->noiseDigi(noise_id, noise_hit));
      }  // loop over noise amplitudes
    } else {
      // no zero suppression, put some noise emulation in **all** empty channels
      // loop through all channels
      for (int layer{0}; layer < n_ecal_layers; layer++) {
        for (int module{0}; module < n_modules_per_layer; module++) {
          for (int cell{0}; cell < n_cells_per_module; cell++) {
            unsigned int channel{ldmx::EcalID(layer, module, cell).raw()};
            // check if channel already has a (real) hit in it
            if (filled_det_i_ds.find(channel) != filled_det_i_ds.end())
              continue;
            // create a digi as put it into the collection
            ecal_digis.addDigi(channel, hgcroc_->noiseDigi(channel));
          }  // cells in each module_
        }  // modules in each layer_
      }  // layers in ECal
    }  // yes or no zero suppression
  }  // if we should do the noise
 
  event.add(digi_coll_name_, ecal_digis);
 
  return;
}  // produce

References ldmx::HgcrocDigiCollection::addDigi(), framework::EventProcessor::getCondition(), ldmx::HgcrocDigiCollection::getNumDigis(), hgcroc_, i_soi_, input_coll_name_, input_pass_name_, mev_, n_adcs_, noise_, noise_generator_, ldmx::DetectorID::raw(), rng_, ldmx::HgcrocDigiCollection::setNumSamplesPerDigi(), ldmx::HgcrocDigiCollection::setSampleOfInterestIndex(), and zero_suppression_.

Member Data Documentation

clock_cycle_

double ecal::EcalDigiProducer::clock_cycle_

private

Time interval for chip clock in ns.

Definition at line 77 of file EcalDigiProducer.h.

Referenced by configure().

digi_coll_name_

std::string ecal::EcalDigiProducer::digi_coll_name_

private

output hit collection name

Definition at line 74 of file EcalDigiProducer.h.

Referenced by configure().

hgcroc_

std::unique_ptr<ldmx::HgcrocEmulator> ecal::EcalDigiProducer::hgcroc_

private

Hgcroc Emulator to digitize analog voltage signals.

Definition at line 110 of file EcalDigiProducer.h.

Referenced by configure(), onNewRun(), and produce().

i_soi_

int ecal::EcalDigiProducer::i_soi_

private

Index for the Sample Of Interest in the list of digi samples.

Definition at line 83 of file EcalDigiProducer.h.

Referenced by configure(), and produce().

input_coll_name_

std::string ecal::EcalDigiProducer::input_coll_name_

private

input hit collection name

Definition at line 68 of file EcalDigiProducer.h.

Referenced by configure(), and produce().

input_pass_name_

std::string ecal::EcalDigiProducer::input_pass_name_

private

input pass name

Definition at line 71 of file EcalDigiProducer.h.

Referenced by configure(), and produce().

mev_

double ecal::EcalDigiProducer::mev_

private

Conversion from energy in MeV to voltage in mV.

Definition at line 86 of file EcalDigiProducer.h.

Referenced by configure(), and produce().

n_adcs_

int ecal::EcalDigiProducer::n_adcs_

private

Depth of ADC buffer.

Definition at line 80 of file EcalDigiProducer.h.

Referenced by configure(), and produce().

noise_

bool ecal::EcalDigiProducer::noise_ {true}

private

Put noise into empty channels, not configurable, only helpful in development.

Definition at line 107 of file EcalDigiProducer.h.

{true};

Referenced by configure(), and produce().

noise_generator_

std::unique_ptr<ldmx::NoiseGenerator> ecal::EcalDigiProducer::noise_generator_

private

Generates noise hits based off of number of cells that are not hit.

Definition at line 123 of file EcalDigiProducer.h.

Referenced by onNewRun(), and produce().

noise_rms_

double ecal::EcalDigiProducer::noise_rms_

private

Noise RMS.

Definition at line 120 of file EcalDigiProducer.h.

Referenced by configure(), and onNewRun().

ns_

double ecal::EcalDigiProducer::ns_

private

Conversion from time in ns to ticks of the internal clock.

Definition at line 113 of file EcalDigiProducer.h.

Referenced by configure().

pedestal_

double ecal::EcalDigiProducer::pedestal_

private

Read out pedestal.

Definition at line 118 of file EcalDigiProducer.h.

Referenced by configure(), and onNewRun().

readout_threshold_

double ecal::EcalDigiProducer::readout_threshold_

private

Read out threshold.

Definition at line 116 of file EcalDigiProducer.h.

Referenced by configure(), and onNewRun().

rng_

std::mt19937 ecal::EcalDigiProducer::rng_

private

Generates random numbers for which channels to fill up with noise.

Definition at line 126 of file EcalDigiProducer.h.

Referenced by onNewRun(), and produce().

zero_suppression_

bool ecal::EcalDigiProducer::zero_suppression_

private

When emulating noise in empty channels, do we zero suppress?

There are two ways to emulate the noise in the chip: 1) (with zero suppression) Use the NoiseGenerator to get a list of amplitudes (about 3-5 on avg) and put those noise hits which are above the readout threshold in random empty channels. 2) (without zero suppresion) Go through all channels and put noise in each channel that doesn't have a real hit in it. This will mean many channels with have a DIGI below readout threshold.

Definition at line 100 of file EcalDigiProducer.h.

Referenced by configure(), and produce().

---

The documentation for this class was generated from the following files:

• Ecal/include/Ecal/EcalDigiProducer.h
• Ecal/src/Ecal/EcalDigiProducer.cxx