HcalSiPM Class Reference

A general implementation for the response of a SiPM. More...

#include <HcalSiPM.h>

Public Member Functions
double	getCrossTalk () const
int	getNCells () const
double	getTau () const
double	getTempDep () const
	HcalSiPM (int nCells=1, double tau=15.)
virtual double	hitCells (CLHEP::HepRandomEngine *, unsigned int pes, double tempDiff=0., double photonTime=0.)
void	resetSiPM ()
void	setCrossTalk (double xtalk)
void	setNCells (int nCells)
void	setSaturationPars (const std::vector< float > &pars)
void	setTau (double tau)
void	setTemperatureDependence (double tempDep)
virtual double	totalCharge () const
virtual double	totalCharge (double time) const
virtual	~HcalSiPM ()

Protected Types
typedef std::unordered_map< unsigned int, cdfpair >	cdfmap
typedef std::pair< unsigned int, std::vector< double > >	cdfpair

Protected Member Functions
unsigned int	addCrossTalkCells (CLHEP::HepRandomEngine *engine, unsigned int in_pes)
double	Borel (unsigned int n, double lambda, unsigned int k)
const cdfpair &	BorelCDF (unsigned int k)
double	cellCharge (double deltaTime) const

Protected Attributes
cdfmap	borelcdfs
HcalSiPMnonlinearity *	nonlin
unsigned int	theCellCount
double	theCrossTalk
double	theLastHitTime
std::vector< double >	theSiPM
double	theTau
double	theTauInv
double	theTempDep

Detailed Description

A general implementation for the response of a SiPM.

Definition at line 22 of file HcalSiPM.h.

Member Typedef Documentation

typedef std::unordered_map< unsigned int, cdfpair > HcalSiPM::cdfmap

protected

Definition at line 50 of file HcalSiPM.h.

typedef std::pair<unsigned int, std::vector<double> > HcalSiPM::cdfpair

protected

Definition at line 49 of file HcalSiPM.h.

Constructor & Destructor Documentation

HcalSiPM::HcalSiPM	(	int	nCells = 1,
		double	tau = 15.
	)

Definition at line 14 of file HcalSiPM.cc.

References resetSiPM(), setTau(), and theCellCount.

                                         :
  theCellCount(nCells), theSiPM(nCells,1.),
  theCrossTalk(0.), theTempDep(0.), theLastHitTime(-1.), nonlin(nullptr)
{
  setTau(tau);
  assert(theCellCount>0);
  resetSiPM();
}

HcalSiPM::~HcalSiPM ( )

virtual

Definition at line 23 of file HcalSiPM.cc.

References nonlin.

                    {
  if (nonlin) delete nonlin;
}

Member Function Documentation

unsigned int HcalSiPM::addCrossTalkCells ( CLHEP::HepRandomEngine *  engine, unsigned int  in_pes  )

protected

Definition at line 82 of file HcalSiPM.cc.

References BorelCDF(), LogDebug, mitigatedMETSequence_cff::U, and up.

Referenced by hitCells().

                                          {
  const cdfpair& cdf = BorelCDF(in_pes);

  double U = CLHEP::RandFlat::shoot(engine);
  std::vector<double>::const_iterator up;
  up= std::lower_bound (cdf.second.cbegin(), cdf.second.cend(), U);

  LogDebug("HcalSiPM") << "cdf size = " << cdf.second.size()
               << ", U = " << U
               << ", in_pes = " << in_pes
               << ", 2ndary_pes = " << (up-cdf.second.cbegin()+cdf.first);

  // returns the number of secondary pes produced
  return (up - cdf.second.cbegin() + cdf.first);
}

double HcalSiPM::Borel ( unsigned int  n, double  lambda, unsigned int  k  )

protected

Definition at line 29 of file HcalSiPM.cc.

References b, JetChargeProducer_cfi::exp, cmsBatch::log, and funct::pow().

Referenced by BorelCDF().

                                                                   {
  if(n<k) return 0;
  double dn = double(n);
  double dk = double(k);
  double dnk = dn-dk;
  double ldn = lambda * dn;
  double logb = -ldn + dnk*log(ldn) - TMath::LnGamma(dnk+1);
  double b=0;
  if (logb >= -20)  { // protect against underflow
    b=(dk/dn);
    if ((n-k)<100)
      b *= (exp(-ldn)*pow(ldn,dnk))/TMath::Factorial(n-k);
    else
      b *= exp( logb );
  }
  return b;
}

const HcalSiPM::cdfpair & HcalSiPM::BorelCDF ( unsigned int  k )

protected

Definition at line 47 of file HcalSiPM.cc.

References b, Borel(), borelcdfs, MillePedeFileConverter_cfg::e, kinem::EPSILON, plotBeamSpotDB::first, mps_fire::i, and theCrossTalk.

Referenced by addCrossTalkCells(), and setCrossTalk().

                                                       {
  // EPSILON determines the min and max # of xtalk cells that can be
  // simulated.
  static const double EPSILON = 1e-6;
  typename cdfmap::const_iterator it;
  it = borelcdfs.find(k);
  if (it == borelcdfs.end()) {
    vector<double> cdf;

    // Find the first n=k+i value for which cdf[i] > EPSILON
    unsigned int i;
    double b=0., sumb=0.;
    for (i=0; ; i++) {
      b = Borel(k+i,theCrossTalk,k);
      sumb += b;
      if (sumb >= EPSILON) break;
    }

    cdf.push_back(sumb);
    unsigned int borelstartn = i;

    // calculate cdf[i]
    for(++i; ; ++i){
      b = Borel(k+i,theCrossTalk,k);
      sumb += b;
      cdf.push_back(sumb);
      if (1-sumb < EPSILON) break;
    }

    it = (borelcdfs.emplace(k,make_pair(borelstartn, cdf))).first;
  }

  return it->second;
}

double HcalSiPM::cellCharge ( double  deltaTime ) const

protected

Definition at line 183 of file HcalSiPM.cc.

References JetChargeProducer_cfi::exp, mps_fire::result, and theTauInv.

Referenced by hitCells(), and totalCharge().

                                                  {
  if (deltaTime <= 0.) return 0.;
  if (deltaTime*theTauInv > 10.) return 1.;
  double result(1. - std::exp(-deltaTime*theTauInv));
  return (result > 0.99) ? 1.0 : result;
}

double HcalSiPM::getCrossTalk ( ) const

inline

Definition at line 38 of file HcalSiPM.h.

{ return theCrossTalk; }

int HcalSiPM::getNCells ( ) const

inline

Definition at line 36 of file HcalSiPM.h.

{ return theCellCount; }

double HcalSiPM::getTau ( ) const

inline

Definition at line 37 of file HcalSiPM.h.

{ return theTau; }

double HcalSiPM::getTempDep ( ) const

inline

Definition at line 39 of file HcalSiPM.h.

References metsig::tau.

{ return theTempDep; }

double HcalSiPM::hitCells ( CLHEP::HepRandomEngine *  engine, unsigned int  pes, double  tempDiff = 0., double  photonTime = 0.  )

virtual

Definition at line 101 of file HcalSiPM.cc.

References addCrossTalkCells(), cellCharge(), digitizers_cfi::pixel, theCellCount, theCrossTalk, theLastHitTime, theSiPM, theTau, and theTempDep.

Referenced by HcalSiPMHitResponse::makeSiPMSignal().

                                 {
  // response to light impulse with pes input photons.  The return is the number
  // of micro-pixels hit.  If a fraction other than 0. is supplied then the
  // micro-pixel doesn't fully discharge.  The tempDiff is the temperature 
  // difference from nominal and is used to modify the relative strength of a
  // hit pixel.  Pixels which are fractionally charged return a fractional
  // number of hit pixels.

  if ((theCrossTalk > 0.) && (theCrossTalk < 1.)) 
    pes += addCrossTalkCells(engine, pes);

  // Account for saturation - disabled in lieu of recovery model below
  //pes = nonlin->getPixelsFired(pes);

  //disable saturation/recovery model for bad tau values
  if(theTau<=0) return pes;

  unsigned int pixel;
  double sum(0.), hit(0.);
  for (unsigned int pe(0); pe < pes; ++pe) {
    pixel = CLHEP::RandFlat::shootInt(engine, theCellCount);
    hit = (theSiPM[pixel] < 0.) ? 1.0 :
      (cellCharge(photonTime - theSiPM[pixel]));
    sum += hit*(1 + (tempDiff*theTempDep));
    theSiPM[pixel] = photonTime;
  }

  theLastHitTime = photonTime;

  return sum;
}

void HcalSiPM::resetSiPM ( )

inline

Definition at line 28 of file HcalSiPM.h.

References lumiContext::fill.

Referenced by HcalSiPM(), and setNCells().

{ std::fill(theSiPM.begin(), theSiPM.end(), -999.); }

void HcalSiPM::setCrossTalk

(

double

xtalk

)

Definition at line 158 of file HcalSiPM.cc.

References BorelCDF(), borelcdfs, gen::k, theCrossTalk, and hgcalDigitizer_cfi::xTalk.

Referenced by HcalSiPMHitResponse::makeSiPMSignal().

                                        {
  // set the cross-talk probability

  double oldCrossTalk = theCrossTalk;

  if((xTalk < 0) || (xTalk >= 1)) {
    theCrossTalk = 0.;
  } else {
    theCrossTalk = xTalk;
  }   

  // Recalculate the crosstalk CDFs
  if (theCrossTalk != oldCrossTalk) {
    borelcdfs.clear();
    if (theCrossTalk > 0)
      for (int k=1; k<=100; k++)
    BorelCDF(k);
  }
}

void HcalSiPM::setNCells

(

int

nCells

)

Definition at line 145 of file HcalSiPM.cc.

References resetSiPM(), theCellCount, and theSiPM.

Referenced by HcalSiPMHitResponse::makeSiPMSignal().

                                   {
  assert(nCells>0);
  theCellCount = nCells;
  theSiPM.resize(nCells);
  resetSiPM();
}

void HcalSiPM::setSaturationPars

(

const std::vector< float > &

pars

)

Definition at line 190 of file HcalSiPM.cc.

References nonlin.

Referenced by HcalSiPMHitResponse::makeSiPMSignal().

{
  if (nonlin)
    delete nonlin;

  nonlin = new HcalSiPMnonlinearity(pars);
}

void HcalSiPM::setTau

(

double

tau

)

Definition at line 152 of file HcalSiPM.cc.

References metsig::tau, theTau, and theTauInv.

Referenced by HcalSiPM(), and HcalSiPMHitResponse::makeSiPMSignal().

                                { 
  theTau = tau;
  if(theTau > 0) theTauInv = 1./theTau;
  else theTauInv = 0;
}

void HcalSiPM::setTemperatureDependence

(

double

tempDep

)

Definition at line 178 of file HcalSiPM.cc.

References theTempDep.

                                                    {
  // set the temperature dependence
  theTempDep = dTemp;
}

virtual double HcalSiPM::totalCharge ( ) const

inlinevirtual

Definition at line 33 of file HcalSiPM.h.

References ntuplemaker::time, and totalCharge().

Referenced by totalCharge().

{ return totalCharge(theLastHitTime); }

double HcalSiPM::totalCharge ( double  time ) const

virtual

Definition at line 134 of file HcalSiPM.cc.

References cellCharge(), mps_fire::i, theCellCount, and theSiPM.

                                              {
  // sum of the micro-pixels.  NP is a fully charged device.
  // 0 is a fullly depleted device.
  double tot(0.), hit(0.);
  for(unsigned int i=0; i<theCellCount; ++i)  {
    hit = (theSiPM[i] < 0.) ? 1. : cellCharge(time - theSiPM[i]);
    tot += hit;
  }
  return tot;
}

Member Data Documentation

cdfmap HcalSiPM::borelcdfs

protected

Definition at line 71 of file HcalSiPM.h.

Referenced by BorelCDF(), and setCrossTalk().

HcalSiPMnonlinearity* HcalSiPM::nonlin

protected

Definition at line 69 of file HcalSiPM.h.

Referenced by setSaturationPars(), and ~HcalSiPM().

unsigned int HcalSiPM::theCellCount

protected

Definition at line 61 of file HcalSiPM.h.

Referenced by HcalSiPM(), hitCells(), setNCells(), and totalCharge().

double HcalSiPM::theCrossTalk

protected

Definition at line 65 of file HcalSiPM.h.

Referenced by BorelCDF(), hitCells(), and setCrossTalk().

double HcalSiPM::theLastHitTime

protected

Definition at line 67 of file HcalSiPM.h.

Referenced by hitCells().

std::vector< double > HcalSiPM::theSiPM

protected

Definition at line 62 of file HcalSiPM.h.

Referenced by hitCells(), setNCells(), and totalCharge().

double HcalSiPM::theTau

protected

Definition at line 63 of file HcalSiPM.h.

Referenced by hitCells(), and setTau().

double HcalSiPM::theTauInv

protected

Definition at line 64 of file HcalSiPM.h.

Referenced by cellCharge(), and setTau().

double HcalSiPM::theTempDep

protected

Definition at line 66 of file HcalSiPM.h.

Referenced by hitCells(), and setTemperatureDependence().