The first check is to test the default PPV and check whether the result is consitent with those from Vertex-Group experts.

GSTAR setup

geometry y2009

BTOF geometry setup:  btofConfig = 12 (Run 9 with 94 trays)

vsig  0.01  60.0
gkine -1 0 0 100 -6.3 6.3 0 6.29 -100.0 100.0
 

PYTHIA setup

MSEL 1         ! Collision type
MSTP (51)=7
MSTP (82)=4
PARP (82)=2.0
PARP (83)=0.5
PARP (84)=0.4
PARP (85)=0.9
PARP (86)=0.95
PARP (89)=1800
PARP (90)=0.25
PARP (91)=1.0
PARP (67)=4.0
 

BFC chain reconstruction options

trs fss y2009 Idst IAna l0 tpcI fcf ftpc Tree logger ITTF Sti VFPPV NoSvtIt NoSsdIt bbcSim tofsim tags emcY2 EEfs evout -dstout IdTruth geantout big fzin MiniMcMk eemcDb beamLine clearmem

Just for record about the PPV cuts:

StGenericVertexMaker:INFO  - PPV::cuts
 MinFitPfrac=nFit/nPos  =0.7
 MaxTrkDcaRxy/cm=3
 MinTrkPt GeV/c =0.2
 MinMatchTr of prim tracks =2
 MaxZrange (cm)for glob tracks =200
 MaxZradius (cm) for prim tracks &Likelihood  =3
 MinAdcBemc for MIP =8
 MinAdcEemc for MIP =5
 bool   isMC =1
 bool useCtb =1
 bool DropPostCrossingTrack =1
 Store # of UnqualifiedVertex =5
 Store=1 oneTrack-vertex if track PT/GeV>10
 dump tracks for beamLine study =0
 

Results

Total 999 events PYTHIA mb events were processed. Among these, 990 events have at least one reconstructed vertex (frac = 99.1 +/- 0.3 %). The following plot shows the "funnyR" plot of the vertex ranking for all found vertices.

Clearly seen is there are lots of vertices with negative ranking. If we define the vertices with positive ranking are "good" vertices, the left plot in the following shows the "good" vertex statistics

Only 376 events (frac 37.6 +/- 1.5 %) have at least one "good" vertex. The middle plot shows the Vz distributions for MC input and the reconstructed first "good" vertices. However, if you look at the right plot which shows the Vz difference between reconstructed vertex and the MC input vertex, not only all good vertices are well distributed, most of any-found vertices even with negative ranking are within 1cm difference.

If we define the "good" vertex is |Vz(rec)-Vz(MC)|<1cm, as Jan Balewski studied in this page: http://www.star.bnl.gov/protected/spin/balewski/2005-PPV-vertex/effiMC/ then 962 events (frac 96.3 +/- 0.6 %) have at least one "good" vertex.

One note about the bfc log, I notice there is a message as the following:

......

 BTOW status tables questionable,
 PPV results qauestionable,

  F I X    B T O W    S T A T U S     T A B L E S     B E F O R E     U S E  !!
 
 chain will continue taking whatever is loaded in to DB
  Jan Balewski, January 2006
......

The full log file is /star/u/dongx/institutions/tof/simulator/simu_PPV/code/default/test.log

Update 9/10/2009

With including BTOF in the PPV, please find the vertex ranking distributions below. (Note: only 94 trays in y2009)

The # of events containing at least one vertex with ranking>0 is 584 (frac. 58.5 +/- 1.6 %). This number is more close to what I have in mind the vertex finding efficiency for pp minibias events. So the early low efficiency was due to missing CTB, while BTOF now is acting like CTB ???

Update 9/22/2009

After several rounds of message exchange with Jan, Rosi etc, I found several places that can be improved.

1) Usually we use the BBC triggered MB events for study. So in the following analysis, I also only select the BBC triggered MB events for the vertex efficiency study. To select BBC triggered events, please refer to the code $STAR/StRoot/StTriggerUtilities/Bbc on how to implement it.

2) Use ideal ped/gain/status for BEMC in the simulation instead of the pars for real data. To turn on this, one need to modify the bfc.C file: add the following lines for the db maker in the bfc.C (after line 123)

    dbMk->SetFlavor("sim","bemcPed"); // set all ped=0 <==THIS
    dbMk->SetFlavor("sim","bemcStatus");  // ideal, all=on
    dbMk->SetFlavor("sim","bemcCalib"); // use ideal gains

These two changes significantly improves the final vertex efficiency (I will show later). The following two are also suggested, although the impact is marginal.

3) Similarly use ideal ped/gain/status for EEMC.

    dbMk->SetFlavor("sim","eemcDbPMTped");
    dbMk->SetFlavor("sim","eemcDbPMTstat");
    dbMk->SetFlavor("sim","eemcDbPMTcal");

4) Use ideal TPC RDO mask. You can find an example here: /star/u/dongx/institutions/tof/simulator/simu_PPV/test/StarDb/RunLog/onl/tpcRDOMasks.y2009.C

With these updates included, the following plot shows the # of good vertex distribution from 500 PYTHIA mb events test.

The vertex efficiency is now raised to ~50%. (OK? low?)

Just as a check on the BBC efficiency, here I accepted 418 events with BBC triggers out of 500 events in total. Eff = 83.6 +/- 1.7 %, which is reasonable.