I've run through 5 events where the vpd and the PPV vertices don't match.   daq file location is:

star/data05/scratch/balewski/2008-daq/st_fmsslow_9060086_raw_1090001.daq

 

Here are the PPV Vz values prior to "forcing" the values.  For the histograms, the solid red lines indicate the location of the vpd vertex and the circles indicate the location(s) of the PPV vertices.

EventID = 749 vpdVz = 98.2939 PPV vertices at Vz = -48.75 140.85

EventID = 2115 vpdVz = -34.348 PPV vertices at Vz = -106.55

EventID = 3346 vpdVz = -33.7838 PPV vertices at Vz = 129.35

EventID = 3952 vpdVz = 0.664319 PPV vertices at Vz =

EventID = 4447 vpdVz = 25.5813 PPV vertices at Vz = -99.95

 

For comparison, here is an event where the VPD vertex and PPV vertex were within 8 cm of each other:

 

All the important files (including the likelihood histograms and track multiplicities) can be found at:

/star/u/rjreed/Vertex3/Eventdaq*

 

Here are the results:

daq #7 EventID = 749 vpdVz = 98.2939 # PPV vertices = 10 at Vz = 90 92 94 96 98 100 102 104 106 108

Primaries that passed the cut (flag>0,  pt>0.2GeV, nFitP/nPoss>0.51):

id = 277 flag = 801 Nhits = 7 Npos = 11 pt = 0.370926 frac = 0.636364

id = 278 flag = 801 Nhits = 6 Npos = 11 pt = 0.250512 frac = 0.545455

id = 279 flag = 801 Nhits = 6 Npos = 11 pt = 0.271426 frac = 0.545455

id = 281 flag = 801 Nhits = 8 Npos = 11 pt = 1.57357 frac = 0.727273

id = 283 flag = 801 Nhits = 6 Npos = 11 pt = 0.638242 frac = 0.545455

id = 292 flag = 801 Nhits = 5 Npos = 9 pt = 0.292521 frac = 0.555556

id = 295 flag = 801 Nhits = 7 Npos = 11 pt = 0.213841 frac = 0.636364

 

daq #22  EventID = 2115 vpdVz = -34.348 N PPV vertices = 10 at Vz = -42 -40 -38 -36 -34 -32 -30 -28 -26 -24

Primaries that passed the cut:

id = 48 flag = 301 Nhits = 40 Npos = 45 pt = 0.362589 frac = 0.888889

id = 63 flag = 301 Nhits = 26 Npos = 34 pt = 0.602728 frac = 0.764706

id = 64 flag = 301 Nhits = 35 Npos = 45 pt = 0.392374 frac = 0.777778

id = 66 flag = 301 Nhits = 32 Npos = 45 pt = 0.772336 frac = 0.711111

id = 288 flag = 801 Nhits = 6 Npos = 11 pt = 2.56192 frac = 0.545455

id = 290 flag = 801 Nhits = 9 Npos = 11 pt = 0.206602 frac = 0.818182

id = 291 flag = 801 Nhits = 10 Npos = 11 pt = 0.556056 frac = 0.909091

id = 292 flag = 801 Nhits = 8 Npos = 11 pt = 0.722384 frac = 0.727273

id = 296 flag = 801 Nhits = 6 Npos = 11 pt = 0.236179 frac = 0.545455

id = 297 flag = 801 Nhits = 6 Npos = 11 pt = 0.267664 frac = 0.545455

id = 298 flag = 801 Nhits = 6 Npos = 11 pt = 0.9994 frac = 0.545455

id = 299 flag = 801 Nhits = 5 Npos = 8 pt = 0.332944 frac = 0.625

id = 300 flag = 801 Nhits = 9 Npos = 11 pt = 0.389091 frac = 0.818182

id = 310 flag = 801 Nhits = 5 Npos = 9 pt = 0.236941 frac = 0.555556

 

daq #44 EventID = 3346 vpdVz = -33.7838 N PPV vertices = 10 at Vz = -42 -40 -38 -36 -34 -32 -30 -28 -26 -24

Primaries that passed the cut:

id = 129 flag = 301 Nhits = 38 Npos = 42 pt = 0.352418 frac = 0.904762

id = 433 flag = 801 Nhits = 6 Npos = 9 pt = 0.73871 frac = 0.666667

id = 436 flag = 801 Nhits = 6 Npos = 11 pt = 4.33162 frac = 0.545455

id = 441 flag = 801 Nhits = 7 Npos = 11 pt = 1.19905 frac = 0.636364

id = 446 flag = 801 Nhits = 6 Npos = 11 pt = 2.52832 frac = 0.545455

 

daq #63 EventID = 3952 vpdVz = 0.664319 N PPV vertices = 10 at Vz = -8 -6 -4 -2 0 2 4 6 8 10

Primaries that passed the cut:

id = 177 flag = 301 Nhits = 35 Npos = 40 pt = 0.751434 frac = 0.875

id = 433 flag = 801 Nhits = 7 Npos = 11 pt = 1.16509 frac = 0.636364

id = 437 flag = 801 Nhits = 6 Npos = 10 pt = 0.277501 frac = 0.6

id = 440 flag = 801 Nhits = 6 Npos = 11 pt = 6.03469 frac = 0.545455

 

daq #70 EventID = 4447 vpdVz = 25.5813 N PPV vertices = 10 at Vz = 18 20 22 24 26 28 30 32 34 36

Primaries that passed the cut:

id = 324 flag = 311 Nhits = 9 Npos = 10 pt = 0.50257 frac = 0.9

id = 391 flag = 801 Nhits = 6 Npos = 11 pt = 0.332764 frac = 0.545455