Merge pull request #6831 from wmtford/QdxCPE

Option to use old CPE error if charge exceeds one MIP
cms-sw · Dec 12, 2014 · b89cf10 · b89cf10
2 parents bcb0416 + 4f6ba70
commit b89cf10
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Showing 3 changed files with 16 additions and 1 deletion.
diff --git a/RecoLocalTracker/SiStripRecHitConverter/interface/StripCPEfromTrackAngle.h b/RecoLocalTracker/SiStripRecHitConverter/interface/StripCPEfromTrackAngle.h
@@ -20,6 +20,10 @@ class StripCPEfromTrackAngle : public StripCPE
   //Set to true if we are using the old error parameterization
   const bool useLegacyError;
 
+  //Clusters with charge/path > this cut will use old error parameterization
+  // (overridden by useLegacyError; negative value disables the cut)
+  const float maxChgOneMIP;
+
 public:  
   StripClusterParameterEstimator::LocalValues
   localParameters( const SiStripCluster&, const GeomDetUnit&, const LocalTrajectoryParameters&) const;
@@ -36,6 +40,7 @@ class StripCPEfromTrackAngle : public StripCPE
 			  const SiStripLatency& latency) 
   : StripCPE(conf, mag, geom, lorentz, backPlaneCorrection, confObj, latency )
   , useLegacyError(conf.existsAs<bool>("useLegacyError") ? conf.getParameter<bool>("useLegacyError") : true)
+  , maxChgOneMIP(conf.existsAs<float>("maxChgOneMIP") ? conf.getParameter<double>("maxChgOneMIP") : -6000.)
   {
     mLC_P[0] = conf.existsAs<double>("mLC_P0") ? conf.getParameter<double>("mLC_P0") : -.326;
     mLC_P[1] = conf.existsAs<double>("mLC_P1") ? conf.getParameter<double>("mLC_P1") :  .618;

diff --git a/RecoLocalTracker/SiStripRecHitConverter/python/StripCPEfromTrackAngle_cfi.py b/RecoLocalTracker/SiStripRecHitConverter/python/StripCPEfromTrackAngle_cfi.py
@@ -17,4 +17,5 @@
    mTEC_P0        = cms.double(-1.885),
    mTEC_P1        = cms.double( .471),
    useLegacyError = cms.bool(True),
+   maxChgOneMIP   = cms.double(-6000.)
 )
diff --git a/RecoLocalTracker/SiStripRecHitConverter/src/StripCPEfromTrackAngle.cc b/RecoLocalTracker/SiStripRecHitConverter/src/StripCPEfromTrackAngle.cc
@@ -1,5 +1,6 @@
 #include "RecoLocalTracker/SiStripRecHitConverter/interface/StripCPEfromTrackAngle.h"
 #include "Geometry/CommonTopologies/interface/StripTopology.h"                                                           
+#include "DataFormats/SiStripCluster/interface/SiStripClusterTools.h"
 
 #include "vdt/vdtMath.h"
 
@@ -38,7 +39,15 @@ localParameters( const SiStripCluster& cluster, const GeomDetUnit& det, const Lo
 
   const unsigned N = cluster.amplitudes().size();
   const float fullProjection = p.coveredStrips( track+p.drift, ltp.position());
-  const float uerr2 = useLegacyError || cluster.isMerged() ? legacyStripErrorSquared(N,std::abs(fullProjection)) : stripErrorSquared( N, std::abs(fullProjection),ssdid.subDetector() );
+  float uerr2;
+  if (useLegacyError) {
+    uerr2 = legacyStripErrorSquared(N,std::abs(fullProjection));
+  } else if (maxChgOneMIP < 0.0) {
+    uerr2 = cluster.isMerged() ? legacyStripErrorSquared(N,std::abs(fullProjection)) : stripErrorSquared( N, std::abs(fullProjection),ssdid.subDetector() );
+  } else {
+    float dQdx = siStripClusterTools::chargePerCM(ssdid, cluster, ltp);
+    uerr2 = dQdx > maxChgOneMIP ? legacyStripErrorSquared(N,std::abs(fullProjection)) : stripErrorSquared( N, std::abs(fullProjection),ssdid.subDetector() );
+  }
   const float strip = cluster.barycenter() -  0.5f*(1.f-p.backplanecorrection) * fullProjection
     + 0.5f*p.coveredStrips(track, ltp.position());