AliRoot status and PDC’04 P.Hristov Monthly video-conference February 06, 2004 CERN

Goals(http://cern.ch/fca/ALICE-DCs.doc) Determine readiness of the off-line framework for data processing Validate the distributed computing model PDC’2004:10% test of the final capacity Complete chain used for trigger studies Prototype of the analysis tools Comparison with parameterized MC Simulated RAW data PDC’04 physics: hard probes (jets, heavy flavours) & pp physics

Physics Data Challenge'2004 Simulation: 10^5 Pb-Pb + 10^7 p-p 102 TB 450 KSI2K (~ tier-1 capacity) x 3 months Distributed production, then data are shipped to CERN Reconstruction: 5x10^6 Pb-Pb+10^7 p-p 187 TB Reconstruction is shared between CERN & outside centres according to available resources Data originate from CERN Analysis: 5x10^6 Pb-Pb+10^7 p-p 13 TB See http://aliweb.cern.ch/people/phristov/PDC04.html

PDC’04 Strategy Part 1: underlying events Distributed simulation, production of summable digits, digitization, clusterization, reconstruction, PID, and generation of ESD Data transfer to CERN: kinematics, track references, summable digits (hits for some detectors) Part 2: signal events & test of CERN as data source Distributed simulation, production of summable digits, merging, digitization, clusterization, reconstruction, PID, generation of ESD Part 3: distributed analysis

AliRoot status New tagged version v4-01-03 from today Works with Root v3-10-02 and Geant3 v0-6 (Geant3 + Geom. Modeller ) Simulation (providing Config.C) AliSimulation sim; Sim.Run(# of events); Reconstruction AliReconstruction rec; Rec.Run();

Simulation Configuration: exists for all signal classes Geometry: OK for all the detectors, many overlaps and extrusions corrected (still some in ITS, TOF) Hijing: fixed problems in the quenching, more reasonable distribution => Use Hijing with quenching and without additional energy dependence Configuration: exists for all signal classes AliEn JDL files: template exists

Summable digits, Digits, Merging Ok for all detectors (if applicable) AliVertexGenFile class to set the correct vertex in Config.C for the signal events (needs read access to the galice.root of the underlying event) AliSimulation class used AliSimulation sim; sim.MergeWith(“../backgr/galice.root”,nSpB); sim.Run(nSignal);

Clusters, Reconstruction, PID, ESD Barrel detectors: OK TRD reconstruction fixed Parallel TPC tracking by default ITS dE/dx PID fixed ESD analysis template available Calorimeters: PHOS – OK, EMCAL – ESD is still empty MUON arm: OK, but has not been tested in a large production => potential problems ESD: needs more users

Observations NewIO: has to be simplified, more rigorous approach needed. Now one has too many opportunities => possibility for errors Folders & Tasks: again strict discipline is needed (object ownership, etc.) ESD: possibility to store intermediate results required (in progress) More attention to simple things (new/delete, pointer initialization, etc.)

Conclusions AliRoot is ready for PDC’04  Well tested simulation and generation of summable digits Some problems still expected in the reconstruction (not all the code is stressed enough) Possibility to incorporate additional features before the second part (signal generation) Possibility to repeat the reconstruction of the underlying events

ToDo Estimation of CPU and storage needs for the signal classes AliEn JDL files Start set of tests with AliEn Start the processing of the underlying events Continue PDC04…