1. Check Laser track of B=0 run and exclude some tracks in order to get precise GGVeff , which in turn is used

when extract T1, T2 value by pos-B and neg-B runs

2. Check Laser track of B=0 run to find mis-alignment, Gating Grid Voltage error distortion and other E field

distortions.

3. Reconstruct vertex using A/C side tracks separately to measure vertex shift due to ExBTwist

1.Most Beams agree with Model Check the difference between ( Model dY vs lX ) and ( Real dY vs lX )

beam by beam B=0 laser run dY = lY (GGV=70V as reference) - lY(GGV=40V) to calculate model dY, C0=1, C1=0, GGVeff = 0.9175*GGVset+3.91 (from Jim)

Good beam Some outliers

zigzag <0.01~0.02 cm

1. But few beams disagree with Model Few beams do not agree with model calculation.There seems to be 2 typical bad beam: systematic raise/fall at Inner/Outer

Bad ?

Bad ?

1. Bad Beam List

Side-Bundle-Rod-Beam, Inner/Outer, raise/fall

My conclusion so far: something bad at A side rod4-beam2,4,5,6 C side rod4-beam4 C side rod5-beam2

Same conclusion if use GGVeff = 0.89627*GGVset -4.60153 (from stefan’s 2nd order cal)

I use laser track cuts: tan <0.9&&some quality cuts(bundle 1,2,3) x (rod 0,1,2,3,4,5) x (beam 0,1,2,4,5,6)

bundle1 bundle2 bundle3

A142,O,f A242,O,f absent

A144,O,r A244,O,r absent

A145,O,r absent A345,O,r

A146,O,r A246,O,r A346,O,r

bundle1 bundle2 bundle3

C152,I absent C352,I

absent C244,I C344,I

2. Some alignment works well Check the residual between ideal lY and measured lY beam by beam B=0 laser run, GGV=70V plot dY(=ideal lY – measured lY) vs lX Unfortunately, ideal lY is NOT ideal because of mirror angle

tilt, but this plot must be linear if there is no distortion and mis-alignment

Inter-Sector

Almost linear suggests small distortionAlignment works well gap ~0.1 cm is corrected

2. Not yet align??

Some inter-sector & inner-outer mis-alignment still exist??Rough criteria is gap above 0.1 cm

2. Bad Alignment??According to 2 plots, alignment procedure make the situation worse…?2 plots are for same chamber, only the laser beam height is different

2. List of “not yet align beam”&”bad align beam”

“not yet align beam” listASide-Rod1-beam1ASide-Rod1-beam2ASide-Rod2-beam1(ASide-Rod0-beam6)(ASide-Rod3-beam6)

CSide-Rod2-beam1(CSide-Rod2-beam5)

“bad align beam” list:ASide-Rod4-Beam1ASide-Rod4-Beam6(Aside-Rod5-beam5)

CSide-Rod3-Beam0Cside-Rod3-Beam1Cside-Rod3-beam2

2. Bending at lX =80 ~120 cm4 plots below are for same beam number, so the geometry is same.But inner sector of right figures are bended

bending

good

bad

2. List of bended trackI use laser track (bundle 2,3) x (rod 0,1,2,3,4,5) x (beam 0,1,2,4,5,6)There are 2 main reasons of track bending GGV error distortion and E field distortion If the bending is happened both for bundle 2 and 3, then the reason may be GGV error distortion as previous graph

ASide-Rod0-Beam4(ASide-Rod0-Beam5)(ASide-Rod1-Beam2)ASide-Rod1-Beam5ASide-Rod2-Beam1(ASide-Rod3-Beam2,4,5)Aside-Rod5-Beam1

CSide-Rod0-Beam4CSide-Rod0-Beam5(CSide-Rod3-Beam1)Cside-Rod3-Beam4,5CSide-Rod4-Beam1CSide-Rod4-Beam4Cside-Rod5-Beam1

Correlation btw chamber tilt and laser track bending

• So far we can not find the sign of Gating Grid Voltage error with real data.

• Any E field distortion around readout chamber cause the drift length independent track distortion

• Misalignment cause 2 effects : coordinate mismatch and extra E field distortion. Chamber tilt is one of the source for E field distortion around the readout chamber.

• The question is Can we extract and distinguish GGV error distortion and chamber tilt distortion using B=0 Laser track?

Some laser track bending can be explained by chamber tilt, but the bending is very large..

0

1

23

4

5A side Bending Laser track and Chamber tilt

04

05

15

12

21

32

34

35

55

51

Sector 54

rod0

Sector 55

1

23

4

5

04

05

31

34

3541

44

51

C side Bending Laser track and Chamber tilt

Conclusion so far

We can not clearly find chamber tilt effect to laser track. The laser track bending may be due to rod shift.

Vertex shift in real data

Vertex Reconstruction Code Vertex reconstruction by A/C side tracks separately Here is a part of the code in AliAnalysisTask:Exec() (please let me know if something wrong about the usage of the

AliVertexerTracks class, because I don’t yet understand in detail )

TObjArray Atrk, Ctrk; UShort_t Aid[ntracks], Cid[ntracks]; // Track loop for (Int_t iTracks = 0; iTracks < ntracks; iTracks++) { AliESDtrack* track = fESD->GetTrack(iTracks); if (!track) { AliExternalTrackParam *t =(AliExternalTrackParam *)track->GetTPCInnerParam(); if(t){

Bool_t ok=kFALSE;ok = AliTracker:: PropagateTrackToBxByBz(t,2.8,track->GetMass(),1,kFALSE);if(ok){ Double_t eta = track->Eta(); Int_t id = track->GetID();

if(eta>0){ Int_t nn=Atrk.GetEntriesFast();

Atrk.AddLast(t); Aid[nn]=id; } if(eta<0){ Int_t nn=Ctrk.GetEntriesFast(); Ctrk.AddLast(t); Cid[nn]=id; }}

} } //track loop AliVertexerTracks *vt = new AliVertexerTracks(5); vt->SetTPCMode(); vt->SetConstraintOff(); AliESDVertex * Apv = vt->FindPrimaryVertex(&Atrk, Aid); AliESDVertex * Cpv = vt->FindPrimaryVertex(&Ctrk, Cid); fhisAV->Fill(Apv->GetX(), Apv->GetY()); fhisCV->Fill(Cpv->GetX(), Cpv->GetY());

3. LHC10b pass1 pp real data

Green :ESDPrimaryVertex

This large shift(~3mm) may be due to the imperfection of pass1 ExBfirst.

Vertex x-y position black-A side, red-C side Left: run116574 (pos-B) Center: run115884 (pos-B) Right: run115325 (neg-B)

Pass1 and pass2We can get pass2 real data recently. Pass1 ExBfirst onlyPass 2 ExBBShape (update version of ExBfirst) ExBTwist (Twist parameter is extracted by Global fitting by Marian)

Vertex Shift Simulation

Include distortion to simulation codeAliTPC.h member AliTPCExBBShape fexbs; AliTPCExBTwist fexbt;

AliTPC.cxx constructor fexbs = new AliTPCExBBShape(); fexbt = new AliTPCExBTwist();

AliTPC.cxx MakeSector function at first fexbs -> SetOmegaTau(0.32, 1.0, 1.0); fexbs->SetBfield(field); fexbt -> SetOmegaTau(0.32, 1.0, 1.0); fexbt -> SetXTwist(0.001);

at primary electron loop fexbs-> GetDistortion(x, roc, dx1); fexbt-> GetDistortion(x, roc, dx2); x = x+dx1+dx2; Something strange about produced simulation data is that

PrimaryVertex in AliESD.root is always (0,0) !! But, anyway, analyze this data

Simulation result of Vertex Shift statistics is small now, so the vertex shift due to ExBBBShape (expected O(~0.1 mm) ) can not be recognized. I produced more data now.

Large Vertex Shift by Twist ??

Maximum distortion is O(0.1mm), but Vertex Shift is O(1mm) !! ??

This is because The vertex is reconstructed by all tracks included large eta tracks

what to do next

I will also produce simulation data include AliTPCBoundaryVoltError