diff --git a/src/THcDC.cxx b/src/THcDC.cxx
index 07eb1c6c3534741db4816b3df667b231e25018f9..26163a942b568ceab8363c9f9e9a61b07469e547 100644
--- a/src/THcDC.cxx
+++ b/src/THcDC.cxx
@@ -404,6 +404,7 @@ Int_t THcDC::CoarseTrack( TClonesArray& /* tracks */ )
for(Int_t i=0;i<fNChambers;i++) {
fChambers[i]->FindSpacePoints();
+ fChambers[i]->CorrectHitTimes();
}
ApplyCorrections();
diff --git a/src/THcDC.h b/src/THcDC.h
index d73491b49572d829720744d6f038eda2db06e7f0..aac69980c7ea9708e8b71e14d59ae4aa339acd5f 100644
--- a/src/THcDC.h
+++ b/src/THcDC.h
@@ -52,6 +52,8 @@ public:
Int_t GetMaxHits(Int_t chamber) const { return fMaxHits[chamber-1];}
Int_t GetMinCombos(Int_t chamber) const { return fMinCombos[chamber-1];}
Double_t GetSpacePointCriterion(Int_t chamber) const { return TMath::Sqrt(fSpace_Point_Criterion2[chamber-1]);}
+ Double_t GetCentralTime(Int_t plane) const { return fCentralTime[plane-1];}
+ Int_t GetDriftTimeSign(Int_t plane) const { return fDriftTimeSign[plane-1];}
Double_t GetPlaneTimeZero(Int_t plane) const { return fPlaneTimeZero[plane-1];}
diff --git a/src/THcDriftChamber.cxx b/src/THcDriftChamber.cxx
index 1a77d4d7f230f59aaed0cc5349e44412130cb4dc..fe2a9c51b85acfeb08b7e1a5baeacda44aec3a99 100644
--- a/src/THcDriftChamber.cxx
+++ b/src/THcDriftChamber.cxx
@@ -119,6 +119,7 @@ Int_t THcDriftChamber::ReadDatabase( const TDatime& date )
prefix[1]='\0';
DBRequest list[]={
{"_remove_sppt_if_one_y_plane",&fRemove_Sppt_If_One_YPlane, kInt},
+ {"dc_wire_velocity", &fWireVelocity, kDouble},
{0}
};
gHcParms->LoadParmValues((DBRequest*)&list,prefix);
@@ -709,20 +710,36 @@ void THcDriftChamber::SelectSpacePoints()
fNSpacePoints = sp_count;
}
-/*
-*
-* Now we know rough hit positions in the chambers so we can make
-* wire velocity drift time corrections for each hit in the space point
-*
-* Assume all wires for a plane are read out on the same side (l/r or t/b).
-* If the wire is closer to horizontal, read out left/right. If nearer
-* vertical, assume top/bottom. (Note, this is not always true for the
-* SOS u and v planes. They have 1 card each on the side, but the overall
-* time offset per card will cancel much of the error caused by this. The
-* alternative is to check by card, rather than by plane and this is harder.
-*/
-
-
+void THcDriftChamber::CorrectHitTimes()
+{
+ // Use the rough hit positions in the chambers to correct the drift time
+ // for hits in the space points.
+
+ // Assume all wires for a plane are read out on the same side (l/r or t/b).
+ // If the wire is closer to horizontal, read out left/right. If nearer
+ // vertical, assume top/bottom. (Note, this is not always true for the
+ // SOS u and v planes. They have 1 card each on the side, but the overall
+ // time offset per card will cancel much of the error caused by this. The
+ // alternative is to check by card, rather than by plane and this is harder.
+ for(Int_t isp=0;isp<fNSpacePoints;isp++) {
+ Double_t x = fSpacePoints[isp].x;
+ Double_t y = fSpacePoints[isp].y;
+ for(Int_t ihit=0;ihit<fSpacePoints[isp].nhits;ihit++) {
+ THcDCHit* hit = fSpacePoints[isp].hits[ihit];
+ THcDriftChamberPlane* plane=hit->GetWirePlane();
+
+ // How do we know this correction only gets applied once? Is
+ // it determined that a given hit can only belong to one space point?
+ Double_t time_corr = plane->GetReadoutX() ?
+ fSpacePoints[isp].y*plane->GetReadoutCorr()/fWireVelocity :
+ fSpacePoints[isp].x*plane->GetReadoutCorr()/fWireVelocity;
+
+ hit->SetTime(hit->GetTime()
+ - plane->GetCentralTime() + plane->GetDriftTimeSign()*time_corr);
+ hit->ConvertTimeToDist();
+ }
+ }
+}
//_____________________________________________________________________________
THcDriftChamber::~THcDriftChamber()
{
diff --git a/src/THcDriftChamber.h b/src/THcDriftChamber.h
index 96c293c0fbe4c6a7600a712c3a907a804cc0413f..0e7b6442d9a073aa44db9850c207f1a070de0651 100644
--- a/src/THcDriftChamber.h
+++ b/src/THcDriftChamber.h
@@ -33,6 +33,7 @@ public:
virtual Int_t ApplyCorrections( void );
virtual void ProcessHits( void );
virtual Int_t FindSpacePoints( void ) ;
+ virtual void CorrectHitTimes( void ) ;
virtual void Clear( Option_t* opt="" );
@@ -66,6 +67,7 @@ protected:
Int_t fMaxHits; // Maximum required to do something
Int_t fMinCombos; // Minimum # pairs in a space point
Int_t fRemove_Sppt_If_One_YPlane;
+ Double_t fWireVelocity;
Double_t fXCenter;
Double_t fYCenter;
diff --git a/src/THcDriftChamberPlane.cxx b/src/THcDriftChamberPlane.cxx
index b23cfe21c160216f272ab7c3abd6cf807802dc2d..8c63c5d9b3a03d385d6bc14c9938776c23e385d0 100644
--- a/src/THcDriftChamberPlane.cxx
+++ b/src/THcDriftChamberPlane.cxx
@@ -110,6 +110,8 @@ Int_t THcDriftChamberPlane::ReadDatabase( const TDatime& date )
fTdcWinMax = fParent->GetTdcWinMax(fPlaneNum);
fPlaneTimeZero = fParent->GetPlaneTimeZero(fPlaneNum);
fCenter = fParent->GetCenter(fPlaneNum);
+ fCentralTime = fParent->GetCentralTime(fPlaneNum);
+ fDriftTimeSign = fParent->GetDriftTimeSign(fPlaneNum);
fNSperChan = fParent->GetNSperChan();
@@ -133,6 +135,14 @@ Int_t THcDriftChamberPlane::ReadDatabase( const TDatime& date )
Double_t hychi = sinalpha*cosgamma;
Double_t hypsi = cosalpha*cosgamma;
+ if(cosalpha <= 0.707) { // x-like wire, need dist from x=0 line
+ fReadoutX = 1;
+ fReadoutCorr = 1/sinalpha;
+ } else {
+ fReadoutX = 0;
+ fReadoutCorr = 1/cosalpha;
+ }
+
Double_t sumsqupsi = hzpsi*hzpsi+hxpsi*hxpsi+hypsi*hypsi;
Double_t sumsquchi = hzchi*hzchi+hxchi*hxchi+hychi*hychi;
Double_t sumcross = hzpsi*hzchi + hxpsi*hxchi + hypsi*hychi;
diff --git a/src/THcDriftChamberPlane.h b/src/THcDriftChamberPlane.h
index 78faf37fefb33635e0c8ac1546c2ea9caf34abe2..e81c9ee5730e37a24169974bbea53fd405c0e0fc 100644
--- a/src/THcDriftChamberPlane.h
+++ b/src/THcDriftChamberPlane.h
@@ -57,6 +57,10 @@ class THcDriftChamberPlane : public THaSubDetector {
Int_t GetPlaneIndex() { return fPlaneIndex; }
Double_t GetXsp() const { return fXsp; }
Double_t GetYsp() const { return fYsp; }
+ Int_t GetReadoutX() { return fReadoutX; }
+ Double_t GetReadoutCorr() { return fReadoutCorr; }
+ Double_t GetCentralTime() { return fCentralTime; }
+ Int_t GetDriftTimeSign() { return fDriftTimeSign; }
protected:
@@ -78,6 +82,11 @@ class THcDriftChamberPlane : public THaSubDetector {
Double_t fXsp;
Double_t fYsp;
+ Int_t fReadoutX;
+ Double_t fReadoutCorr;
+ Double_t fCentralTime;
+ Int_t fDriftTimeSign;
+
Double_t fCenter;
Double_t fNSperChan; /* TDC bin size */