CSCStripHitSim Class Reference

#include <CSCStripHitSim.h>

Public Member Functions
std::vector< CSCDetectorHit > &	simulate (const CSCLayer *layer, const std::vector< CSCDetectorHit > &wireHits)

Private Attributes
std::vector< CSCDetectorHit >	newStripHits
CSCGattiFunction	theGattiFunction

Detailed Description

Class which builds simulated strip hits from wire hits during digitization of Endcap Muon CSCs.

Author

Rick Wilkinson

Definition at line 21 of file CSCStripHitSim.h.

Member Function Documentation

std::vector< CSCDetectorHit > & CSCStripHitSim::simulate	(	const CSCLayer *	layer,
		const std::vector< CSCDetectorHit > &	wireHits
	)

Definition at line 12 of file CSCStripHitSim.cc.

References CSCGattiFunction::binValue(), CSCLayer::chamber(), funct::cos(), relativeConstraints::geom, CSCLayer::geometry(), CSCGattiFunction::initChamberSpecs(), SiStripPI::max, min(), CSCLayerGeometry::nearestStrip(), newStripHits, CSCChamberSpecs::nNodes(), CSCLayerGeometry::numberOfStrips(), PFRecoTauDiscriminationByIsolation_cfi::offset, position, funct::sin(), CSCChamber::specs(), CSCLayerGeometry::stripAngle(), CSCLayerGeometry::stripPitch(), theGattiFunction, CSCLayerGeometry::wireAngle(), CSCLayerGeometry::xOfStrip(), and CSCLayerGeometry::yOfWire().

Referenced by CSCDigitizer::doAction().

{
  // make sure the gatti function is initialized
  const CSCChamberSpecs * chamberSpecs = layer->chamber()->specs();
  const CSCLayerGeometry* geom = layer->geometry();
  theGattiFunction.initChamberSpecs(*chamberSpecs);
  const int nNodes = chamberSpecs->nNodes();
  
  // for every wire hit, induce a Gatti-distributed charge on the
  // cathode strips
  newStripHits.clear();
  newStripHits.reserve((2*nNodes+1)*wireHits.size());
  std::vector<CSCDetectorHit>::const_iterator wireHitI;
  for(wireHitI = wireHits.begin(); wireHitI != wireHits.end(); ++wireHitI){
    int   wire        = (*wireHitI).getElement();
    float wireCharge  = (*wireHitI).getCharge();
    float wireHitTime = (*wireHitI).getTime();
    // The wire hit position is _along the wire_, measured from where
    // the wire intersects local y axis, so convert to local x...
    float hitX   = (*wireHitI).getPosition() * cos(geom->wireAngle());
    float hitY   = geom->yOfWire(wire, hitX);
    const LocalPoint wireHitPos(hitX, hitY);

    int centerStrip = geom->nearestStrip(wireHitPos);
    int firstStrip = std::max(centerStrip - nNodes, 1);
    int lastStrip  = std::min(centerStrip + nNodes, geom->numberOfStrips());
    for(int istrip = firstStrip; istrip <= lastStrip; istrip++) {
      float offset = hitX - geom->xOfStrip(istrip, hitY);
      float stripWidth = geom->stripPitch(wireHitPos);
      float binValue = theGattiFunction.binValue(offset, stripWidth);
      // we divide by 2 because charge goes on either cathode.
      // if you're following the TDR, we already multiplied the
      // charge by 0.82 in the WireHitSim (well, DriftSim), so that explains 
      // their f_ind=0.41.
   
      // this seems to be folded in the Amp response, which peaks
      // around 0.14.  The difference may be because the amp response
      // convolutes in different drift times.
      //float collectionFraction = 0.19;
      const float igain = 1./0.9; // mv/fC
      float stripCharge = wireCharge * binValue * igain * 0.5;
      float stripTime = wireHitTime;
      float position = hitY / sin(geom->stripAngle(istrip));
      CSCDetectorHit newStripHit(istrip, stripCharge, position, stripTime, 
                                   (*wireHitI).getSimHit());
      newStripHits.push_back(newStripHit);
    }
  }  // loop over wire hits
  return newStripHits;
}

Member Data Documentation

std::vector<CSCDetectorHit> CSCStripHitSim::newStripHits

private

Definition at line 29 of file CSCStripHitSim.h.

Referenced by simulate().

CSCGattiFunction CSCStripHitSim::theGattiFunction

private

Definition at line 28 of file CSCStripHitSim.h.

Referenced by simulate().