v4-16-Release: bug reports, committed fixes and proposed changes

P. Hristov29/05/2009

Weekly offline meeting

Committed changes

• #50614: 4-prong D0-> Kstar pi pi not switched off for kHadronicDWithout4Bodies.

• #50598: SHUTTLE subprocessor

• #44266: Introduce the Bethe-Bloch function in AliMathBase

– From rev. 30153,32438: Too many changes…

• bug #48080: Dip at zero in the distribution of Delta-phi and d: PbPb events

Proposed fixes

• #50766 qPythia in AliEn

– From rev. 31669, 31684, 32299, 32303

• #50763 Fluka Simulation of single particles: Crash when PIPE is on

– From rev. 31126

• #50755 TOF Online Calibration - Changes in the Release required

– From rev. 30347, 30917, 31388, 31791, 31798, 31841, 31843, 32173, 32383, 32384

• #50317 Correct AliGenPythia for B-jet studies

– Patch exists, corresponds to rev. 32558

New reports + 5 already closed

• #51010 Validation error of grid jobs (production)

• #50935 Raw PID signals for the electron candidates in AOD

• #50934 Sensitivity studies: calibration and the systematic effects in reconstruction

• #50931 New representation of the PID signal for ITS (4 floating numbers instead of 1)

• #50930 Low track matching efficiency with TOF

• #50922 Inefficiency (40%) for secondaries reconstruction in the TPC

• #50874 Implement AliAnalysisAlien::Print ?

• #50855 Correction for the track segment length in AliITSpidESD2

(Black = v4-16-Release, Blue=trunk)

Reports + 10 closed (20/05/09)• #50665 CTP interaction records to be added to ESD?

• #50609 esd_tracks.C displays events wrongly when simulated with neg mag field

• #50456 Macros and AliRoot for multiple EMCAL productions

• #50446 LocalBoardId [MUON cosmic production]

• #50437 MUON QA checkers not working [MUON cosmic production]

• #50436 MUON DE0510 mapping problem [MUON cosmic production]

• #50435 MUON Station2 mapping/geometry problem [MUON cosmic production]

• #50432 MUON cosmic RecoParam [MUON cosmic production]

• #50430 MUON KillMap [MUON cosmic production]

• #50391 Implementing the possibility to correct the tracking for non-zero transverse components of the B-field.

(Black = v4-16-Release, Blue=trunk)

Reports + 11 closed (14/05/09)

• #50416 TRD tracks not propagated to the outer wall of TPC

• #50254 Additional info in ESD track for TRD PID [request]

• #50225 AliAODHandler doesn't work correctly with merged events

• #50174 Index out of bound in TPC digitization for ppbench

(Black = v4-16-Release, Blue=trunk)

Old slides (20/05/09)

High priority (my selection)

• #49416 ClusterFinder - too many deconvoluted clusters

– No news

• #48981 Problem in "on the flight" V0 finder

– No news

Active investigations:#48080 Dip at zero in the distribution of Delta-phi and d: PbPb events

• The origin of the problem is identified: the function AliITStrackV2:GetLocalXat and AliITStrackV2:GetLocalZat had a protection that excluded the propagation if the radius was smaller than the estimated DCA.

– Improved protections were provided by Ruben & Martin

• A feature was corrected: mismatch between the current phi of the track momentum and position (Andrea)

• Additional investigations of the propagation and material corrections

• More news during the PWG1 meeting

Old slides: 14/05/09

Active investigations: #47881 Position of outer track parameter not symmetric and not “outer”

1. The AliTPCtrack::PropagateTo function was modified. In case of step outside of TPC volume the track is not propagated.(The material description is not correct)

2. For unknown reason the TRD updates the Outer parameters even being outside of the acceptance. The code responsible was not localized.

3. Running the same reconstruction code without and with outer detectors the efficiency to refit decrease from 100 % to 98 %. The effect is visible mainly for big theta.

The TPC outer parameters have to be backuped in the AliESDfriend and incase of big difference (>n sigma) between TPC backup and current AliESDtrack parameters have to be replaced.

Active investigations: #49294: High-pt fake tracks are produced in 0 < phi < 30

0. I agree with Youri that we should apply proposed cut (on the relative precision of 1/PT). On top we have to minimize tails in pt pulls. The tail will define our cut.

1. The width of the pt pulls for tracks not decaying in the TPC is around(1,1.1) (TPC stand alone)

2. In case the particle decays inside of the TPC significant the tails of the distribution are more significant and the width is two times bigger.

3. The deterioration also visible in case particle decays inside of the TRD and the TRD info is used for refit.

To be done:

1. Backup TPC outer information in ESD friend track and start TPC refit from this point if the mismatch between current param. and backup is bigger than n-sigma threshold.

2. 2. Check all high pt tracks for kink point which can cause the tails in 1/pt residuals.

Active investigations: #44264: Shift in the reconstructed PT

Observed pt shift and strong dependence of this shift on the theta is explained by not taking the Br and Brfi component of the mag field into account in AliExternalTrackParam::PropagateTo. It is not detector related.

The correction for p_t can be roughly estimated deltapt/pt ~ pz/pr * Br/Bz The fact that the effect is not detector specific can be demonstrated using the exact MC track references instead of the detector clusters in the reconstruction.(The code AliMCTrackingTestTask::FitTrackRefs+see attached picture.)

Conclusion:

1. ALL components of mag field should be taken into account in the propagate method.

2. Effect is proportional to the Br/Bz which is on the level of 0-2%

3. The effect of the vxB effect to the angular and position shift can not beneglected

4. Somebody should impliment as soon as possible correct PropagateTo method -not approximation - as all parameters are affected.

Active investigations: #46277: TPC z shift

The theta dependent z shift for track extrapolated to the TRD is observed also from the fit of MC data in case the Br and Brfi field is neglected during track propagation. The effect is also pt dependent, basically the track is deflected by a fraction a curvature in y direction.

Using tracks from your production /lustre/alice/local/TRDdata/SIM/P-Flat/TRUNK I got the slope about -0.4 mm/tan(theta) for tracks bellow 1 GeV.For tracks over 2 GeV the slope ( from MC fitting) was negligible.

I do not say that this is full explanation, but currently the first task is to implement correct Propagate method.

Active investigations: #46277: TPC z shift

I added new data memebers to the AliESDfriend track AliExternalTrackParam * fTPCOut; // tpc outer parameters AliExternalTrackParam * fITSOut; // its outer parameters AliExternalTrackParam * fTRDIn; // trd inner parameters

There are 2 reasons why I want to add them.

1. I can discard the information from outer detectors in case there is big chi2 mismatch between fTPCout and current ESDtrack parameters. (because of kink decays, big -non consistent material budget correction, and also bugs)

2. We can do QA - matching of the track parameters from different detectors.

Active investigations

• #48080 Dip at zero in the distribution of residuals (phi-angle, impact parameter in the transverse plane): PbPb events

– Investigated by Martin, Andrea,Yuri and Francesco

– Reproduced with pp events when vertexer Z is used instead of vertexer 3D.

– Doesn’t depend on the XY position of the vertex: forcing X=0, Y=0 in vertexer 3D doesn’t reproduce the problem.

– Using (0,0,0) as vertex doesn’t reproduce the dip (possibly because of the smearing).

– Switching off AliITStrackV2::Improve method (return at the first line) “cures” the dip with vertexer Z. Confirmed.

– Still a lot of work needed…

Old slides 07/05/09

Previous reports

• #49538 PbPb bench crash:F-TGeoPcon::ComputeBBox: Wrong section order

– AliSHILv3 has to be fixed

• #48898 Different track indices in the ESD kink loop and the ESD track loop

– “Marian knows how to fix the problem”. Second reminder is sent.

• #48748 Number of foundable clusters in TPC needs refinement

– No news

• #48360 Every MC production job writes an object back to OCDB. Temporary modification in sim.C/rec.C

Previous reports II

• #44511: Eta dependency of PID efficiency dE/dx not OK

#46796: Multiply reconstructed tracks (phi = 0 and 180 deg) ~1% fake tracks. This is consistent with the particle decays when some clusters

from the daughter track are assigned to the mother one or vice versa.

More investigations?

Work in progress (?)

#46278: Bug/artifact in SPD tracklet finding

Caused by the selection on DeltaPhi in the ITS vertexer 3D. PB to decide.

#46372: Primary vertex reconstruction: events with multiple primary vertices

Preliminary results shown

The updates in the ESD available in the trunk

Proposal: introduce it when we start pileup production with v4-16-Release

Work in progress (?)

#47452: TPC drift velocity correction

(was TPC-TOF matching in LHC08d raw-data reconstruction)

Affects not only TOF matching but also all the other barrel detectors

Laser and ITS/TPC matching algorithms will give the absolute Vdrift (under development)

Low number of laser tracks prevents (~30 instead of ~300/event) is an obstacle for the calibration

#45031: LHC machine parameters to go into GRP

Presented at the physics board. My understanding of the decision: take all the information.

Proposal: implementation upon the PB's decision, not urgent for current MC production

Other reports

• #47413 Correct treatment (in both cluster- and track finders) of the SSD modules that are dead on one side

– New development, not assigned.

• #47412 The tracking and PID efficiency for secondary anti-protons is higher than for secondary protons: artifact in the definition of “findable” track, still under investigation

• #47411 Implementing a "PID consistency check" with efficiency constant over momentum. No news.

• #47410 Improvements in the stand-alone ITS tracker: taking into account the energy losses, possibility to start from the outer. No news