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 int	hitCells (CLHEP::HepRandomEngine *, unsigned int photons, unsigned int integral=0) const
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	setTau (double tau)
void	setTemperatureDependence (double tempDep)
virtual double	totalCharge () const
virtual double	totalCharge (double time) const
virtual	~HcalSiPM ()

Protected Member Functions
double	cellCharge (double deltaTime) const

Protected Attributes
unsigned int	theCellCount
double	theCrossTalk
double	theLastHitTime
std::vector< double >	theSiPM
double	theTauInv
double	theTempDep

Detailed Description

A general implementation for the response of a SiPM.

Definition at line 20 of file HcalSiPM.h.

Constructor & Destructor Documentation

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

Definition at line 11 of file HcalSiPM.cc.

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

                                         :
  theCellCount(nCells), theSiPM(nCells,1.), theTauInv(1.0/tau),
  theCrossTalk(0.), theTempDep(0.), theLastHitTime(-1.) {

  assert(theCellCount>0);
  resetSiPM();
}

HcalSiPM::~HcalSiPM ( )

virtual

Definition at line 19 of file HcalSiPM.cc.

                    {
}

Member Function Documentation

double HcalSiPM::cellCharge ( double  deltaTime ) const

protected

Definition at line 139 of file HcalSiPM.cc.

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

Referenced by hitCells(), and totalCharge().

                                                  {
  if (deltaTime <= 0.) return 0.;
  if (deltaTime > 10./theTauInv) 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.

References theCrossTalk.

{ return theCrossTalk; }

int HcalSiPM::getNCells ( ) const

inline

Definition at line 36 of file HcalSiPM.h.

References theCellCount.

{ return theCellCount; }

double HcalSiPM::getTau ( ) const

inline

Definition at line 37 of file HcalSiPM.h.

References theTauInv.

{ return 1.0/theTauInv; }

double HcalSiPM::getTempDep ( ) const

inline

Definition at line 39 of file HcalSiPM.h.

References theTempDep.

{ return theTempDep; }

int HcalSiPM::hitCells ( CLHEP::HepRandomEngine *  engine, unsigned int  photons, unsigned int  integral = 0  ) const

virtual

Definition at line 22 of file HcalSiPM.cc.

References create_public_lumi_plots::exp, timingPdfMaker::mean, mathSSE::sqrt(), theCellCount, theCrossTalk, and x.

Referenced by HcalSiPMHitResponse::makeSiPMSignal().

                                                                                                      {
  //don't need to do zero or negative photons.
  if (photons < 1) return 0;
  if (integral >= theCellCount) return 0;

  //normalize by theCellCount to remove dependency on SiPM size and pixel density.
  if ((theCrossTalk > 0.) && (theCrossTalk < 1.)) {
    CLHEP::RandPoissonQ randPoissonQ(*engine, photons/(1.-theCrossTalk)-photons);
    photons += randPoissonQ.fire();
  }
  double x(photons/double(theCellCount));
  double prehit(integral/double(theCellCount));

  //calculate the width and mean of the distribution for a given x
  double mean(1. - std::exp(-x));
  double width2(std::exp(-x)*(1-(1+x)*std::exp(-x)));

  //you can't hit more than everything.
  if (mean > 1.) mean = 1.;

  //convert back to absolute pixels
  mean *= (1-prehit)*theCellCount;
  width2 *= (1-prehit)*theCellCount;

  double npe;
  while (true) {
    npe = CLHEP::RandGaussQ::shoot(engine, mean, std::sqrt(width2 + (mean*prehit)));
    if ((npe > -0.5) && (npe <= theCellCount-integral))
      return int(npe + 0.5);
  }
}

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

virtual

Definition at line 54 of file HcalSiPM.cc.

References cellCharge(), theCellCount, theCrossTalk, theLastHitTime, theSiPM, and theTempDep.

                                 {
  // 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.)) {
    CLHEP::RandPoissonQ randPoissonQ(*engine, pes/(1. - theCrossTalk) - pes);
    pes += randPoissonQ.fire();
  }

  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 26 of file HcalSiPM.h.

References lumiContext::fill, and theSiPM.

Referenced by HcalSiPM(), and setNCells().

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

void HcalSiPM::setCrossTalk

(

double

xtalk

)

Definition at line 111 of file HcalSiPM.cc.

References theCrossTalk.

                                        {
  // set the cross-talk probability

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

}

void HcalSiPM::setNCells

(

int

nCells

)

Definition at line 104 of file HcalSiPM.cc.

References assert(), resetSiPM(), theCellCount, and theSiPM.

Referenced by HcalSiPMHitResponse::makeSiPMSignal().

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

void HcalSiPM::setTau ( double  tau )

inline

Definition at line 42 of file HcalSiPM.h.

References metsig::tau, and theTauInv.

Referenced by HcalSiPMHitResponse::makeSiPMSignal().

{theTauInv=1.0/tau;}

void HcalSiPM::setTemperatureDependence

(

double

tempDep

)

Definition at line 122 of file HcalSiPM.cc.

References theTempDep.

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

virtual double HcalSiPM::totalCharge ( ) const

inlinevirtual

Definition at line 32 of file HcalSiPM.h.

References theLastHitTime, and totalCharge().

Referenced by totalCharge().

{ return totalCharge(theLastHitTime); }

double HcalSiPM::totalCharge ( double  time ) const

virtual

Definition at line 83 of file HcalSiPM.cc.

References cellCharge(), 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

unsigned int HcalSiPM::theCellCount

protected

Definition at line 52 of file HcalSiPM.h.

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

double HcalSiPM::theCrossTalk

protected

Definition at line 55 of file HcalSiPM.h.

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

double HcalSiPM::theLastHitTime

protected

Definition at line 57 of file HcalSiPM.h.

Referenced by hitCells(), and totalCharge().

std::vector< double > HcalSiPM::theSiPM

protected

Definition at line 53 of file HcalSiPM.h.

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

double HcalSiPM::theTauInv

protected

Definition at line 54 of file HcalSiPM.h.

Referenced by cellCharge(), getTau(), and setTau().

double HcalSiPM::theTempDep

protected

Definition at line 56 of file HcalSiPM.h.

Referenced by getTempDep(), hitCells(), and setTemperatureDependence().