Explanation of the commit to StSsdDbMaker 

in SL07d (as well as for SL08c), wrong geometry is loaded for plain simulation.

Following are the residuals of hits dX = X_mc -X_reco and dY = Y_mc - Y_reco 

Fig 1. dX vs . Ladder

Fig2. dY vs. Ladder

Whereas using the Fast Simulator gives residuals at 0 :

Fig3 . dX v. Ladder (fast)

Fig4. dY vs. Ladder (fast)

The reason are the following.

m_dimensions    =  (St_ssdDimensions     *)

GetInputDB("Geometry/ssd/ssdDimensions");

00076   m_positions = CalculateWafersPosition();

00077   if ((!m_dimensions)||(!m_positions)) {

00078     gMessMgr->Error() << "No  access to geometry parameters" << endm;

00079     return kStFatal;

00080   }

 

where we calculate the positions of wafers.

I was a bit confused by the log, when running the fast and slow simulators

because both have :

LoadTable: .L

 

/afs/rhic.bnl.gov/star/packages/SL07d/StarDb/Geometry/ssd/SsdOnGlobal.20050310.000000.C

LoadTable: .L

/afs/rhic.bnl.gov/star/packages/SL07d/StarDb/Geometry/ssd/SsdSectorsOnGlobal.20050310.000012.C

LoadTable: .L

/afs/rhic.bnl.gov/star/packages/SL07d/StarDb/Geometry/ssd/SsdLaddersOnSectors.20050310.000018.C

LoadTable: .L

/afs/rhic.bnl.gov/star/packages/SL07d/StarDb/Geometry/ssd/SsdWafersOnLadders.20050101.000000.C

 

but for the fast simulator, the VMC geometry is after loaded in

StSsdFastSimMaker :

 

Load TFile:  

/afs/rhic.bnl.gov/star/packages/SL07d/StarDb/VmcGeometry/Detectors.y2007.root

LoadTable: .L

/afs/rhic.bnl.gov/star/packages/SL07d/StarDb/VmcGeometry/Geometry.y2007.C

StSsdFastSimMaker:INFO  - CreateGeometry : File y2007.h has been found as

/afs/rhic.bnl.gov/star/packages/SL07d/StarDb/VmcGeometry/y2007.h

StSsdFastSimMaker:INFO  - TGeoManager::TGeoManager : Geometry y2007,

y2007.h created

StSsdFastSimMaker:INFO  - TGeoMaterial::ctor : Material AIR defined with

fractional Z=7.300000

[...]

StSsdFastSimMaker:INFO  - TGeoManager::CloseGeometry : 439952 nodes/ 2223

volume UID's in y2007.h

StSsdFastSimMaker:INFO  - TGeoManager::CloseGeometry :

----------------modeler ready----------------

Load TFile:  

/afs/rhic.bnl.gov/star/packages/SL07d/StarDb/VmcGeometry/geom.y2007.root

StSsdFastSimMaker:DEBUG - Geometry Loaded

 

As a result,the ideal geometry is loaded and the residuals vs. ladder are

at 0.

 

In the slowSimulator, when the StSsdbMaker is called to built the barrel,

I guess that it keep these ssdWafersOnLadders.C table and use it for

making the ssdWaferPositions.C table.

 

What i plan to do is :

 if(m_Mode ==1 ){

    m_positions = (St_ssdWafersPosition  *)

GetInputDB("Geometry/ssd/ssdWafersPosition");}

  else

    {

      m_positions = CalculateWafersPosition();

    }

 

And with this, I get proper residuals, ie at 0, for both SL07d and SL08c.

 

check 1 :

these plots show the residuals in X and Y before and after the fix for the same events in simulation

dX withtout

dX with

dY without

dY with

 

check 2 :

I run the real data (as StSsdDbMaker.cxx is also used for them), with and without the fix.

Positions of hits are the same --> correct

Logs are here :

with fix 

without fix

In this log file are the positions (drift,normal,transverse and center) of each wafer :

here