PPV vertex finder code have been upgraded and default changed as follows.

(July 9, 2009)

1) the threshold for pT of  single-matched-track vertices was lowered from 15 GeV/c to 10 GeV/c.
The purpose if this change is to not loose W-events for the case when TPC calibration is approximate and error of reco PT of TPC track is sizable for tracks with true PT of 20 GeV/c.
Those vertices will be now more likely pileup contaminated, since there is a fair chance for a random matching of a global track to a fired BTWO tower. Users should use vertices with at least 2 matched tracks which will have rank>1e6.

2) Additional expert-only functionality was added to PPV , encapsulated in the new class Vertex3D.

If BFC is run in normal way, e.g. in production no new action is taken.

However if BFC option "VtxSeedCalG" is added for every event high quality most likely primary tracks candidates from the pool of global tracks:

• use only global tracks matched to BTOW,ETOW, or central membrane
• require nFit/nPoss>51%, and Rxy @ DCA to X=Y=0 below 3 cm
• require PPV finds valid vertex along Z direction, require delZ <3cm
• require global pT in range [0.8, 8.0] GeV/c

and printed in to the logfile in the format:

      printf("track4beamLine %f %f %f   %f %f %f   %f %f %f   %d %f  %.1f %d \n",x,y,z,px,py,pz,er->_cYY,er->_cZY,er->_cZZ , tr.nFitPoint,tr.gChi2,z0,eveID);

Fig. 1. prim tracks candidates in the vicinity of beam line

Fig. 2. QA plots for prim track selection