# Sti Tracking

Some attempts to do the tracking with Sti includind ssd hits or mot and see if there are differences
Files used : /star/data10/reco/cuProductionMinBias/FullField/P05if_test/2005/049/st_physics_6049032_raw_1010008.event.root
Here are the residuals in Z ,X and Y and are defined as :
difference between the coordinates of the first hit and the dca point of the helix fit to the first point == hit position - helix position
(Click on the picture to enlarge. A new window will open.)
Not includind ssd points in the tracking
 Picture 1: residual in Z Picture 2: residual in X Picture 3: residual in Y

(Click on the picture to enlarge. A new window will open.)
Includind ssd points in the tracking
 Picture 1: residual in Z Picture 2: residual in X Picture 3: residual in Y

Comments : this is very preliminary and this is not final results because there are still stuffs to fix :
1. need more stats
2. if the ssd is not well aligned , then we associate wrong hits
3. the hit association is using , for the ssd , the defaults parameters which are for the resolution in Z = 20 microns and in X/Y = 20 microns but we must use real resolution which are 700 microns in Z and 20 microns in X/Y
I can load differents parameters from a .dat file from StiMaker/macros/ssdInputFile.dat but this is private code and this is still a thing I have to do
4. In Sti/StiHitErrorCalculator.cxx : there is a shift between parameters in Z and X/Y
These parameters are clearly define as :
coeff[0]= intrinsicZ;
coeff[1]= driftZ;
coeff[2]= crossZ;
coeff[3]= intrinsicX;
coeff[4]= driftX;
coeff[5]= crossX;
then it calculates :
ecross=coeff[0]+coeff[1]*dz/(cosCA*cosCA) +coeff[2]*tanCA*tanCA;
if (ecross< 1e-4) ecross = 1e-4;
if (ecross> 1 ) ecross = 1;
double tanDip=node->getTanL();
double cosDipInv2=1+tanDip*tanDip;
edip=coeff[3]+coeff[4]*dz*cosDipInv2+coeff[5]*tanDip*tanDip;
My problem is that in this formula for the calculation of edip , it uses coef[3],coef[4],coef[5] ,whereas it must use coef[0],coef[1],coef[2] ( which are the parameters for the Z axis I hope) ?
edip == delta ( Z ) because there are uses both the dip Angle and delta(Z) uses all the parameters linked to the Z Axis but here , it seems that edip is not uses the good parameters.

# hits in detectors

number of primaries tracks vs detectors , eg cases are :
1. 0 == there are hits in tpc for this primary
2. 1== there are hits in tpc and svt
3. 2== there are hits in tpc and ssd
4. 3== there are hits in svt and ssd
5. 4== there are hits in tpc, svt, ssd

# dca

dca of the primaries for tpc+svt ( kind==1 && present==1) and for tpc+svt+ssd ( kind==1 && present==4)

(Click on the picture to enlarge. A new window will open.)
 Picture 1: dca (tpc+svt) Picture 2: dca (tpc+svt+ssd)

Jonathan Bouchet