goal : has the PXL geometry in Sti an impact on the physics ?
idea : generate the decay gamma→e+e- and find the V0 decay vertex. In principle, electron conversion should appear in material then the PXL geometry should be seen if decayX vs. decayY is plotted

simulation :

• 100k events with 1 gamma
• geometry : y2013_1

study :

• look at the .fz file
• run the BFC with PXL in Sti and try to reconstruct the V0 vertex 

1) Simulation

Secondary vertices were found by looping over the g2t_track table and for entries >0 ( first entry is the primary vertex)
Figure 1 : all secondary vertices

ENHANCE !

Figure 2 : secondary vertices in [-50,50] cm in XY

ENHANCE !

Figure 3 : secondary vertices in [-10,10] cm in XY
PXL geometry :10 naked sectors and 3 equipped sectors : 2-4-7) are cleary seen.

Figure 4 : radius of decay vertices


Figure 5 : Z position of decay vertices with the requirement radius < 10 ( PXL )

2) Comparison with no PXL in the geometry
I used y2013_2 where the PXL has been removed ,according to here.
I have generated 60k events in both cases

Figure 6 : secondary vertices in [-50,50] cm in XY for no PXL
We can see that the PXL structures are not seen/here, which is what we expect. There is still something at radius ~12.5 cm (PST ?)
The inner circle is the beam pipe


Figure 7 : radius of conversion : black line = no PXL, red crosses = with PXL


Figure 8 : same as Figure 7 but in the interesting region.
We can distinguish a second peak after ~2.5 for the PXL case , which can be beam pipe + PXL inner layer as opposed as beam pipe alone.
The second bin has an entry for the PXL case( red cross) and no entry for the TPC only (black line)
We also see another large area for radius ~8 cm , which is the PXL outer layer.