Alice off-line meeting

40-S2-A01 (CERN)



Carminati, F.
    • 09:00 09:30
      Geometrical Modeller news 30m
      Speaker: Gheata, A. (CERN)
      A.Gheata presented the status of the new Geometrical Modeler. N.Van Eijndhoven asked what would be the choice to be made when the modeler would be fully implemented. F.Carminati answered that we should abandon all the other geometrical packages and use the new one. F.Rademakers asked about the cumulative timescale of the project: there was no precise estimation, but the main work should be done before the end of the summer.
    • 09:05 09:35
      Status of AliRoot - FLUKA integration 30m
      Speaker: Hrivnacova, I. (IPN, Orsay)
      I.Hrivnacova gave a talk on the AliRoot - Fluka integration. F.Carminati asked what should be done in order to use the Geant4 geometry. One has to verify the changes in the geometry of some detectors and merge them with the updated CVS version.
    • 09:10 09:30
      Status of Geant4 testing 20m
      Speaker: Gonzalez, I. (CERN)
      I. Gonzalez showed the results of the Geant4 hadronic tests. There was a clear difference between the experimental and simulated distributions. He was asked whether the discrepancy could partially be explained with the normalization. The answer was negative.
    • 09:15 09:35
      Kalman filter parameterisation for TPC 20m
      Speaker: Dainese, A. (INFN, Padova)
      A.Dainese presented his work on a Kalman track parametrization in TPC. N.DiBari asked if the difference in the covariance matrix for pions and kaons was important for the charm studies. No, because it affects only the low momenta. K.Safarik asked about the efficiency checks. There was a difference around dead regions in the TPC, which were passive in the simulation and no first hit was available. K.Safarik noted that one could play with the vertex constraint due to the presence of bremsstrahlung.
    • 09:20 09:40
      Physical observables with SPD 20m
      Speaker: Virgili, T. (INFN, Salerno)
    • 09:25 09:45
      TOF reconstruction and PID 20m
      Speaker: Pierella, F. (INFN, Bologna)
      Question by A. Morsch: How you use the TGeant3 Geometry? Answ: We need the GEANT3 geometry during the geometrical propagation of the extracted TPC tracks in order to know if, at a given step, the particle reach the TOF detector and, if yes, the identifier of current volume (e.g. if it is a TOF sensitive volume or not et cetera). This is the reason why the TOF reconstruction needs to create an instance of the ALICE geometry (gAlice->Init() ). Considering also that geometry has to be known only for TOF detector, usually, in the Config.C, only the frame and the TOF detector are switched on. Question by Ivana Hrivnacova: Concerning this point, what are the GEANT functions are you using? Answ: The GEANT function which we are using are: Gmedia Gcvolu gcvolu->names[i] gcvolu->glx[2] Ivana:It would be usefull to put this method on a more basic level (e.g. in AliMC). Answ: Yes, of course, I will send to You the code with some comment explaining exactly our needs. Question by D. Di Bari: Concerning the probabilistic approach to particle identification, the contour cuts you are using for PID will be replaced by the amplitude method? Answ: Yes, of course, it is only the present status of the code. We will move to probabilistic phylosophi for PID asap. Question by A. Dainese: Fabrizio, this slide is sayng that you can use different contour cuts for PID. Answ: Yes, in fact, I said that the AliTOFPID class has only (as data member) the pointer to external file containing cuts. A. Dainese: could you provide the std contour cuts in CVS? Answ: Yes, of course, we will commit asap the std contour cuts used for Pb-Pb and pp PID. A. Dainese: But in any case, the AliTOFPID class uses the output of the reconstruction. Answ: Yes Andrea, we can provide to You the reconstructed data. In any case the code for the TOF reconstruction will be committed in few days. Remark by K.Safarik: Why You do not use Kalman tracking for the matching, the method for the Kalman propagation till external detectors is already available? Answ: This is a good new. If You provide this method, we can move to Kalman quickly. Please, can we meet? Remark by K.Safarik: Concerning the event time zero determination, there is not longer need to use a combinatorial algorithm (which is bad), you can use the time zero calculated from all identified pions -> In this way, due to the high statistics, you can get in principle a resolution (time resolution/sqrt(N_pions)) Answ: Yes, but I'd like to verify this formula. The current combinatorial algorithm do not use PID (because it can be used also for PID). Please remember that if You take all identified pions, You get also identified pions -but matched with a wrong time, due to noise- and this can to make worse Your resolution for the event time zero determination. In any case I will try and I will let You know. Question by P. Hristov: Could You provide a set of test macros for TOF? Answ: Yes Peter, I promise ;)
    • 09:30 09:50
      Status of V0 finding (V1 of tracking) 20m
      Speaker: Lo Re, G. (INFN, Catania)
      G.LoRe spoke about the status of V0 finding within the version 1 of ITS tracking. Y.Foka asked about the differences between the current approach and one presented by the Strasbourg group. The same reconstruction was used, but HIJING generator was used instead of the parametrization. M.Kowalski asked about the two possible solutions in case of helix tracking. It might happened, but usually the second solution is too far from the vertex and could be easily identified. N.DiBari asked how the track weights were taken into account. They were not, the mid-point was considered as vertex. The cut on the distance was not momentum-dependent, so the multiple scattering was not taken into account. M.Kowalski pointed to another consequence of the multiple scattering; the distribution on Y-coordinate has non-gaussian tails. A small discrepancy in the estimated number of K0 with the talk of Y.Belikov was due to the different definitions. Y.Foka suggested to apply uniform definitions in order to compare the results.
    • 09:35 09:55
      Attempts of neural tracking in ALICE 20m
      Speaker: Pulvirenti, A. (INFN, Catania)
      A.Pulvirenti presented a neural network approach to the tracking in ITS. B.Nilsen proposed to reduce the size of the network by applying it only within a segment. B.Batunia asked what was the source of increased efficiency with respect to the previous results. The improvement is due to the tracks without TPC prolongation.
    • 09:40 10:00
      ZDC status 20m
      Speaker: Oppedisano, C. (INFN, Torino)
    • 09:45 10:15
      Simulation Status 30m
      Speaker: Morsch, A. (CERN)
      A.Morsch showed the simulation status. B.Nilsen asked if the MUON dipole field was included: yes, it was. There was also a question on the pp charm tuning. It was done with PbPb events for the nucleon parton structure functions.
    • 09:50 10:10
      Framework Status 20m
      Speaker: Rademakers, F. (CERN)
      F.Rademakers spoke about the framework status. J.Chudoba asked whether Proof could be used both for interactive and batch jobs. It could be used since the load is dynamic and the result will not depend on the slowest node. P.Buncic described some possible problems in the simulation related to the fact that our unit is one event.
    • 09:55 10:25
      Off-line Status 30m
      Speaker: Carminati, F. (CERN)
    • 10:00 10:30
      Reconstruction Status 30m
      Speaker: Safarik, K (CERN)
      K.Safarik gave a talk on the reconstruction. B.Nilsen asked about the definition of a good track in ITS. The 6 points requirement is used in order to compare with the old results, but it doesn't fully correspond to the expected efficiency for a given signal. One has to study the isolation cuts, etc. The reconstruction efficiency is important also for event-by-event analysis and should be as good as possible.
    • 10:05 10:35
      Production Infrastructure 30m
      Speaker: Buncic, P. (CERN)
      P.Buncic presented the status of the production infrastructure. Y.Schutz pointed out that some more work should be done on the fault scenarios.
    • 10:10 10:25
      Staring with MOSIX 15m
      Speaker: Adamova, D. (NPI, Prague)
    • 10:15 10:30
      AliRoot Release & Status 15m
      Speaker: Hristov, P. (CERN)