V0 Reconstruction

file = /star/data10/reco/cu62productionMinBias/FullField/DEV_ssd/2005/073/st_physics_6073006_raw_1010001.event.root
CuCu@62 GeV : 863 events
For now, there isn't any geometrical cuts.

Figures 1-3 are K0 invariant mass plots for STI (SVT + SSD Hits including).


Figure 1 : no cuts	Figure 2 : nHits Pos > 15 && nHits Neg > 15	Figure 3 : DecayLengthV0 > 6

Figures 4-6 are Tranverse Momentum of K0 for STI (SVT + SSD Hits including).


Figure 4 : no cuts	Figure 5 : nHits Pos > 15 && nHits Neg > 15	Figure 6 : DecayLengthV0 > 6

Figures 7-9 are K0 invariant mass plots for STI (SSD Hit including only and no SVT Hits).


Figure 7 : no cuts	Figure 8 : nHits Pos > 15 && nHits Neg > 15	Figure 9 : DecayLengthV0 > 6

When Sti is not including SVT Points

tracks	with only tpc points	with tpc and ssd hit
globals	113179	6005
primarys	60345	22722

When Sti is including SVT Points

tracks	with only tpc points	with tpc and at least 1 svt point	with tpc,ssd and at least 1 svt point
globals	108144	6689	2715
primarys	43307	17076	13001

Few comments : For both cases, when we add a point from the vertex detectors (SSD or SVT), the number of tracks (globals + primarys) decreases .
But the number of primarys compare to globals increases.
The inclusion of the SSD with at least 1 point from the SVT is decreasing these lasts numbers, ie there are less tracks with TPC+SSD+ (at least) 1 SVT point than tracks with only TPC+(at least) 1 SVT point.

Comparison with the defaults errors parameters and realistic errors parameters

The hit errors parameters and tracking parameters are store in : /afs/rhic.bnl.gov/star/packages/DEV/StarDb/Calibrations/tracker :

ssdHitError.20010311.000000.C
ssdTrackingParameters.20010311.000000.C

The errors parameters for the SSD are : coeff[0]= intrinsicZ
coeff[1]= driftZ
coeff[2]= crossZ
coeff[3]= intrinsicX
coeff[4]= driftX
coeff[5]= crossX
The defaults values are : coeff[0]= 0.002 cm
coeff[1]= 0
coeff[2]= 0
coeff[3]= 0.002 cm
coeff[4]= 0
coeff[5]= 0
whereas we expect coeff[0]= 700 microns for the intrinsic resolution in the Z direction
The next results are just the differences I obtained when I set coeff[0]= 0.07
With the defaults parameters :
file = /star/data10/reco/cu62productionMinBias/FullField/DEV_ssd/2005/073/st_physics_6073006_raw_1010002.event.root
For all tracks (47977) :

for the globals tracks (28382):
1. 26725 have 0 SSD hit
2. 1650 have 1 SSD hit
3. 7 have 2 SSD hits (I don't understand this)
for the primarys tracks (19595)
1. 13792 have 0 SSD hit
2. 5779 have 1 SSD hit
3. 24 have 2 SSD hits

With coeff[0]= 700 microns and for the same sample :
For all tracks (47980) :

for the globals tracks (28353):
1. 26556 have 0 SSD hit
2. 1783 have 1 SSD hit
3. 14 have 2 SSD hits
for the primarys tracks (19627)
1. 13001 have 0 SSD hit
2. 6589 have 1 SSD hit
3. 37 have 2 SSD hits

I get almost the same number of globals and primary tracks but the number of primary tracks including a SSD hit is bigger with coeff[0]= 0.07.
It is normal because the window of the research for adding a point depends with this parameter.
So as the window is bigger, we have more chance to find a SSD hit to the track. file = /star/data10/reco/cu62productionMinBias/FullField/DEV_ssd/2005/073/st_physics_6073006_raw_1010001.event.root
file = /star/data10/reco/cu62productionMinBias/FullField/DEV_ssd/2005/073/st_physics_6073006_raw_1010002.event.root
DCA vs pt range : - here

3 april : DCA and pT ,with and without ssd hit

file = /star/data10/reco/cu62productionMinBias/FullField/DEV_ssd/2005/073/st_physics_6073006_raw_1010001.event.root
file = /star/data10/reco/cu62productionMinBias/FullField/DEV_ssd/2005/073/st_physics_6073006_raw_1010002.event.root
file = /star/data10/reco/cu62productionMinBias/FullField/DEV_ssd/2005/073/st_physics_6073006_raw_1010003.event.root
file = /star/data10/reco/cu62productionMinBias/FullField/DEV_ssd/2005/073/st_physics_6073006_raw_1010004.event.root
file = /star/data10/reco/cu62productionMinBias/FullField/DEV_ssd/2005/073/st_physics_6073006_raw_1010005.event.root
file = /star/data10/reco/cu62productionMinBias/FullField/DEV_ssd/2005/073/st_physics_6073006_raw_1010006.event.root
file = /star/data10/reco/cu62productionMinBias/FullField/DEV_ssd/2005/073/st_physics_6073006_raw_1010007.event.root
Cut on primary vertex |zvertex|< 30 cm

The first goal is to compare how changes the pt,dca distributions when we include or not a ssd hit.

For the tracks :
DCA vs N Tpc points : - here
Fit DCA distribution ,N Tpc points = 20 : - here
Fit DCA distribution ,N Tpc points = 30 : - here
Fit DCA distribution ,N Tpc points = 40 : - here
DCA vs pt range : - here

For the VO reconstructed :
DCA to prim Vtx vs N Tpc points of the daughters : - here
DCA to prim Vtx vs DecayLength of V0 (Tpc points of the daughters = 15) : - here
DCA to prim Vtx vs pT of V0 (N Tpc points of the daughters = 15) : - here

Jonathan Bouchet

Last modified: Tue Apr 4 03:03:40 EDT 2006