1. Current Status of the VTX analysis
Takashi HACHIYA
2014/2/20
Radiation lab meeting

2. Analysis Status of c/b separation
Primary purpose is
Show the new (preliminary) result from the CuAu analysis at QM14
Finalize the AuAu and pp analysis as soon as possible
It it not likely to show the final result of the AuAu at QM14
Analysis status for AuAu after QM12
Improving the DCA distribution using new production
Tracking algorithm and chi-square(VTX-CNT) calculation was improved, as I showed at the previous meeting.
Deadmap and Alignment were updated.
Unstable channels were masked.
Additional 30% data is available (which was not used for QM12 analysis)
Repeating QM12 analysis with new cuts.
New DCA unfolding method is being introduced (show later)
2014/2/20
Radiation lab meeting

3. Production Status Production DONE: Production plan
Second Run11 Au+Au production is done
A bug in the code killed the strip layers artificially
It is desired to rerun the production
Run12 Cu+Au production is done
QA plot shows some VTX ladder have misalignment
Studying how much the performance get worse.
Production plan
CuAu production for FVTX
Run12 Pp 200 production for VTX (reproduction)
Under discussion for the further production
(Run11AuAu or Run14AuAu or)
2014/2/20
Radiation lab meeting

4. Mis-Alignment in CuAu
Some mis-alignment were found (reported by Hidemitsu)
Strip has a big mis-alignment in both phi and Z direction
We are working what makes this mis-alignment
People didn’t trust this QA plots.
A bug in QA code? A bug in the alignment procedure? Human error?
We found at least there is one human error
There is a typo between iteration of the alignment (6mm shifted by hand)
Phi residual (hit – track)
Phi residual (hit – track)
B0 west
B0 east
B1 west
B1 east
B0 west
B0 east
B1 west
B1 east
B2 west
B2 east
B3 west
B3 east
B2 west
B2 east
B3 west
B3 east
Out of Range
2014/2/20
Radiation lab meeting

5. Hadron DCA and chi2/ndf from CuAu & AuAu (minbias)
The shape around the peak is similar for CuAu and AuAu
DCA width is 84um (CuAu) and 78um (AuAu)
Mis-alignment in CuAu remain a little?
The background yield (flat area) is larger for AuAu
Chi2/ndf show similar, but a bit wider for CuAu
There is some mis-alignment in CuAu, but not so terribly bad
We can use this CuAu production for the analysis
2014/2/20
Radiation lab meeting

6. DCA unfolding New method is being tested Status: Original :
Fit DCA distribution for each pT slice independently
New method: (andrew and alan)
Fit DCA and pT distribution simultaneously
Sweeping the input parameter space and looking for the maximum log likely food
Similar method with what used for Jet reconstruction
Status:
Using a toy MC model, the new method can reproduce the input c/b distribution
The AuAu result will be appeared soon using QM12 DCA distribution.
We are working with p+p too
2014/2/20
Radiation lab meeting

7. Toy MC example Input Shape Unfolding result Input (B+D) Pythia shape
Pameter space
Unfolding
The unfolded result reproduces the input shape. Good!
More detail, please see
Testing with changing the parameter spaces
First result using QA12 spectra is coming soon
For the DATA unfolding, we plan to use pT spectra from ppg77(run4) and DCA (run11)
2014/2/20
Radiation lab meeting

8. Summary Analysis for AuAu and CuAu is on-going DCA unfolding
New production data for AuAu and CuAu is available
Mis-alignment effect is not so severe.
DCA unfolding
A toy MC test is in good shape
First result using DATA is soon
2014/2/20
Radiation lab meeting

9. 2014/2/20
Radiation lab meeting

10. Hadron DCA from CuAu & AuAu (minbias)
The shape around the peak is similar for CuAu and AuAu
DCA width is 84um (CuAu) and 78um (AuAu)
Mis-alignment in CuAu remain a little?
The background yield (flat area) is larger for AuAu
2014/2/20
Radiation lab meeting

11. Hadron Chi2/ndf w/ 4hits from CuAu & AuAu
Chi2/ndf is similar and a little steeper for AuAu
Mis-alignment in CuAu remain a little? ( same tendency with DCA)
But AuAu has a large tail in log scale (right plot)
I suspect that the background makes this tail (see next page)
I will check this with the veto cut
Here, Veto cut was not used.
2014/2/20
Radiation lab meeting

12. Centrality dependence of chi2/ndf
CuAu
AuAu
ET distribution
Chi2/ndf changes with centrality
Central collisions have more tails (it seems that background makes the tail)
I think we must use same multiplicity event when comparing the distribution.
From ET distribution, ET (most ~= ET(Mid AuAu)
This corresponds to the CuAu and the AuAu
The shape is similar
2014/2/20
Radiation lab meeting

13. Hadron DCA2D vs phi in CuAu and AuAu
Black line : mean position (profile of 2D hist)
Track cut : 1<pT<2GeV/c, nhit>=3, chi2/ndf<3,
CuAu
AuAu
Phi
Phi
No veto cut,
Acceptance is more flat. GOOD!
Peak position is mostly aligned for both CuAu and AuAu
The CuAu looks a bit spreaded for the west (phi~ -0.5)
The AuAu has a shift around phi=2.2. but almost out of acceptance
We can tune the DCA position to be 0 by the recalibrator . (if it is desired)
2014/2/20
Radiation lab meeting

14. DCA unfolding
Electron pT and DCA shape from B and D decays are calculated using the probability function (assuming PYTHIA - kinematics)
Looking for the maximum log likely hood using this calculated template with changing input assumption
Likely-hoot for pT and DCA are combined using a certain weight
2014/2/20
Radiation lab meeting