From 2eba5f37b6aa62f8756271ff60c43f63511e019b Mon Sep 17 00:00:00 2001
From: hallc-online <hallconline@gmail.com>
Date: Wed, 14 Mar 2018 16:47:37 -0400
Subject: [PATCH] Modified THcDriftChamber
1) Add to tree variable arrays stub_x,stub_xp,stub_y and stub_yp
and ncombos. These are arrays of the number of spacepoints in
the chamber.
2) In ReadDatabase
a) new variable fRatio_xpfp_to_xfp which is set differently
for HMS and SHMS. Used in method LeftRight
b) Set default value of optional parameter fStubMaxXPDiff = 999.
3) Modified method LeftRight
a) Previously only for the old fHMSStyleChambers would
the code only select LR combinations where
the difference between stub_xp to space_point_X*ratio is
with in the fStubMaxXPDiff .
The ratio came from the HMS optics.
b) Changed LeftRight so that if fStubMaxXPDiff < 100
then the code will only select LR combinations where
the difference between stub_xp to space_point_X*ratio is
with in the fStubMaxXPDiff . The ratio is
set in ReadDataBase according to the spectrometer.
5) In FindSpacePoints add some comments.
---
src/THcDriftChamber.cxx | 76 ++++++++++++++++++++++++++++++++++-------
src/THcDriftChamber.h | 1 +
2 files changed, 64 insertions(+), 13 deletions(-)
diff --git a/src/THcDriftChamber.cxx b/src/THcDriftChamber.cxx
index 0062a5e..0a446d7 100644
--- a/src/THcDriftChamber.cxx
+++ b/src/THcDriftChamber.cxx
@@ -137,18 +137,23 @@ Int_t THcDriftChamber::ReadDatabase( const TDatime& date )
DBRequest list[]={
{"_remove_sppt_if_one_y_plane",&fRemove_Sppt_If_One_YPlane, kInt,0,1},
{"dc_wire_velocity", &fWireVelocity, kDouble},
- {"SmallAngleApprox", &fSmallAngleApprox, kInt},
+ {"SmallAngleApprox", &fSmallAngleApprox, kInt,0,1},
{"stub_max_xpdiff", &fStubMaxXPDiff, kDouble,0,1},
{"debugflagpr", &fhdebugflagpr, kInt},
{"debugstubchisq", &fdebugstubchisq, kInt},
{Form("dc_%d_zpos",fChamberNum), &fZPos, kDouble},
{0}
};
-
+ fSmallAngleApprox=0;
+ fRatio_xpfp_to_xfp=1.0;
+ TString SHMS="p";
+ TString HMS="h";
+ TString test=prefix[0];
+ if (test==SHMS ) fRatio_xpfp_to_xfp=0.0018; // SHMS
+ if (test == HMS ) fRatio_xpfp_to_xfp=0.0011; // HMS
fRemove_Sppt_If_One_YPlane = 0; // Default
- fStubMaxXPDiff = 0.05; // The HMS default. Not used for SOS.
+ fStubMaxXPDiff = 999.; //
gHcParms->LoadParmValues((DBRequest*)&list,prefix);
-
// Get parameters parent knows about
THcDC* fParent;
fParent = (THcDC*) GetParent();
@@ -229,6 +234,11 @@ Int_t THcDriftChamber::DefineVariables( EMode mode )
{ "spacepoints", "Space points of DC", "fNSpacePoints" },
{ "nhit", "Number of DC hits", "fNhits" },
{ "trawhit", "Number of True Raw hits", "fN_True_RawHits" },
+ { "stub_x", "", "fSpacePoints.THcSpacePoint.GetStubX()" },
+ { "stub_xp", "", "fSpacePoints.THcSpacePoint.GetStubXP()" },
+ { "stub_y", "", "fSpacePoints.THcSpacePoint.GetStubY()" },
+ { "stub_yp", "", "fSpacePoints.THcSpacePoint.GetStubYP()" },
+ { "ncombos", "", "fSpacePoints.THcSpacePoint.GetCombos()" },
{ 0 }
};
return DefineVarsFromList( vars, mode );
@@ -266,7 +276,47 @@ void THcDriftChamber::PrintDecode( void )
Int_t THcDriftChamber::FindSpacePoints( void )
{
-
+ /*
+1) First check if number of hits is between fMinHits=min_hit and fMaxHits=max_pr_hits
+ if fails then fNSpacePoints=0
+2) Determines if it is an easy spacepoint.
+ a) if HMS style chambers finds the Y and Y' planes
+ if not HMS style chambers finds the X and X' planes
+ b) if both planes ahve only one hit and the difference in hit position
+ between the hits < fSpacePointCriterion and less than 6 hits .
+ then easy spacepoint and calls either method FindEasySpacePoint_HMS or FindEasySpacePoint_SOS
+ c) FindEasySpacePoint_SOS
+ 1) Loops through hits and gets y_pos from the non-X planes and determines average Yt
+ 2) Loops through hits and sees if any of "Y-planes" hits has
+ difference of y_pos -Yt > TMath::Sqrt(fSpacePointCriterion/2.0)
+ 3) Adds a spacepoint and set ncombos to zero.
+
+
+3) if not EasySpacePoint calls FindHardSpacePoints
+ a) loops though hits and determines pairs of hits in planes with angles grerater then 17.5 degs
+ between them. These are test pairs and stores the x and y position of pair
+ b) Double loops through the test pairs to determine number of pair combinations.
+ i) Calculates d2 = (xi -xj)^2 + (yi-yj)^2 from the two pairs (i,j).
+ ii) If d2 < fSpacePointCriterion then fills combos structure with pair info
+ and increments ncombos.
+ c) Loop through ncombos
+ i) First combo is set as spacepoint which is loaded with hit info from combos.
+ ii) Next combo
+ a) Loops through previous space points
+ b) calculates d2 = (x_c -x_sp)^2 + (y_c-y_sp)^2 between combos and spacepoint
+ if d2 < fSpacePointCriterion then adds combos hit info to that spacepoint
+ which is not already in the spacepoint.
+ c) if that combo is not already added to existing spacepoint
+ then new spacepoint is made from the combo.
+4) If it found a spacepoint
+ i) For HMS-style chamber it would DestroyPoorSpacePoints if fRemove_Sppt_If_One_YPlane
+ ii) Presently if HMS-style chamber calls SpacePointMultiWire()
+ iii) Calls ChooseSingleHit this looks to see if two hits in the same plane.
+ If two hits then rejects on with longer drift time.
+ iv) calls SelectSpacePoints. Goes through the spacepoints and eliminates spacepoints
+ that do not have nhits > min_hits and ncombos> min_combos
+ ( exception for easyspacepoint)
+ */
fSpacePoints->Clear();
Int_t plane_hitind=0;
@@ -1038,7 +1088,7 @@ void THcDriftChamber::LeftRight()
Int_t nhits = sp->GetNHits();
UInt_t bitpat = 0; // Bit pattern of which planes are hit
Double_t minchi2 = 1.0e10;
- Double_t tmp_minchi2;
+ Double_t tmp_minchi2=1.0e10;
Double_t minxp = 0.25;
Int_t hasy1 = -1;
Int_t hasy2 = -1;
@@ -1137,11 +1187,11 @@ void THcDriftChamber::LeftRight()
}
}
if (nplaneshit >= fNPlanes-1) {
- Double_t chi2 = FindStub(nhits, sp,
- plane_list, bitpat, plusminus, stub);
+ Double_t chi2;
+ chi2 = FindStub(nhits, sp,plane_list, bitpat, plusminus, stub);
if (fdebugstubchisq) cout << " pmloop = " << pmloop << " chi2 = " << chi2 << endl;
if(chi2 < minchi2) {
- if(fHMSStyleChambers) { // Perhaps a different flag here
+ if (fStubMaxXPDiff<100. ) {
// Take best chi2 IF x' of the stub agrees with x' as expected from x.
// Sometimes an incorrect x' gives a good chi2 for the stub, even though it is
// not the correct left/right combination for the real track.
@@ -1152,8 +1202,7 @@ void THcDriftChamber::LeftRight()
}
Double_t xp_fit=stub[2]-fTanBeta[plane_list[0]]
/(1+stub[2]*fTanBeta[plane_list[0]]);
- // Tune depdendent. Definitely HMS specific
- Double_t xp_expect = sp->GetX()/875.0;
+ Double_t xp_expect = sp->GetX()*fRatio_xpfp_to_xfp;
if(TMath::Abs(xp_fit-xp_expect)<fStubMaxXPDiff) {
minchi2 = chi2;
for(Int_t ihit=0;ihit<nhits;ihit++) {
@@ -1161,6 +1210,7 @@ void THcDriftChamber::LeftRight()
}
sp->SetStub(stub);
} else { // Record best stub failing angle cut
+ if (chi2 < tmp_minchi2) {
tmp_minchi2 = chi2;
for(Int_t ihit=0;ihit<nhits;ihit++) {
tmp_plusminus[ihit] = plusminus[ihit];
@@ -1168,6 +1218,7 @@ void THcDriftChamber::LeftRight()
for(Int_t i=0;i<4;i++) {
tmp_stub[i] = stub[i];
}
+ }
}
} else { // Not HMS specific
minchi2 = chi2;
@@ -1179,8 +1230,7 @@ void THcDriftChamber::LeftRight()
}
///////////////
} else if (nplaneshit >= fNPlanes-2 && fHMSStyleChambers) { // Two planes missing
- Double_t chi2 = FindStub(nhits, sp,
- plane_list, bitpat, plusminus, stub);
+ Double_t chi2 = FindStub(nhits, sp,plane_list, bitpat, plusminus, stub);
//if(debugging)
//if (fhdebugflagpr) cout << "pmloop=" << pmloop << " Chi2=" << chi2 << endl;
// Isn't this a bad idea, doing == with reals
diff --git a/src/THcDriftChamber.h b/src/THcDriftChamber.h
index a7fbc24..ede4dc8 100644
--- a/src/THcDriftChamber.h
+++ b/src/THcDriftChamber.h
@@ -93,6 +93,7 @@ protected:
Int_t fHMSStyleChambers;
Int_t fhdebugflagpr;
Int_t fdebugstubchisq;
+ Double_t fRatio_xpfp_to_xfp; // Used in selecting stubs
Double_t fZPos;
Double_t fXCenter;
Double_t fYCenter;
--
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