Offline Tutorial I. Małgorzata Janik Łukasz Graczykowski. Warsaw University of Technology

Transcription

1 Offline Tutorial I Małgorzata Janik Łukasz Graczykowski Warsaw University of Technology Offline Tutorial,

2 Contents ALICE experiment AliROOT ROOT GRID & AliEn Event generators - Monte Carlo Methods Transport Packages (Geant3, Geant4, Fluka) Simulation and reconstruction AliRoot svn structure Simulation, reconstruction and visualization in practice (hands on) 2 Offline Tutorial, , Małgorzata Janik, Łukasz Graczykowski

3 ALICE 3

4 ALICE Check videos on: 4

5 AliROOT 5

6 AliROOT 6

7 ROOT The ROOT system provides a set of ObjectOriented (OO) C++ frameworks with all the functionality needed to handle and analyze large amounts of data in a very efficient way. Having the data defined as a set of objects, specialized storage methods are used to get direct access to the separate attributes of the selected objects, without having to touch the bulk of the data. (ROOT trees) Thanks to the built-in CINT C++ interpreter the command language, the scripting, or macro, language and the programming language are all C++. The interpreter allows for fast prototyping of the macros since it removes the, time consuming, compile/link cycle. 7

8 AliROOT 8

9 AliEn & Grid GRID Is a distributed computing system, the combination of computer resources from multiple institutions. CERN maintains the LHC Computing Grid (LCG) to handle the huge amounts of data which are delivered by the LHC with storage rates exceeding several gigabytes per second and allows to perform complex analyses for them. AliEn is a lightweight Grid framework developed by CERN. It is built around Open Source components using the combination of Web Service and distributed agent model. It is being developed by the ALICE collaboration as a production environment for the simulation, reconstruction and analysis of physics data. 9

10 AliROOT 10

11 Event generators 11

12 MC Event Generators Event generators are software libraries that generate simulated highenergy particle physics events. They randomly generate events as those produced in particle accelerators, collider experiments or during the initial phases of the Universe creation. In other words, they are tools enabling the description of the final states resulting from high-energy collisions. These tools are called Monte Carlo (MC) codes because the state-of-the-art knowledge about Quantum Chromo Dynamics (QCD) is implemented in them using numerical MC techniques. HIJING Pythia Phojet Hadronic event generator 12 Hadronic event generator Heavy-Ion event generator

13 Monte Carlo methods Loop over x random value 1 y random value 2 //if point (x,y) belongs to the inside of the circle If(sqrt( x^2 + y^2) < r ) { hits = hits + 1; } 13

14 AliROOT 14

15 Transport packages implementation (in ALICE) 15

16 Transport packages in ALICE GEANT 3 Geant 3 main transport package in ALICE, written in FORTRAN Geant 4 will replace Geant 3 soon, written in C++ FLUKA used only for tests (not officially), written FORTRAN 16 Offline Tutorial, , Małgorzata Janik, Łukasz Graczykowski

17 GEANT GEometry ANd Tracking The GEANT program describes the passage of elementary particles through the matter. Originally designed for the High Energy Physics experiments, it has today found applications also outside this domain in the areas of medical and biological sciencies, radioprotection and astronautics. The principal applications of GEANT in High Energy Physics are: the tracking of particles through an experimental setup for simulation of detector response the graphical representation of the setup and of the particle trajectories Offline Tutorial, , Małgorzata Janik, Łukasz Graczykowski

18 ALICE 18 Eva Sicking, ALICE's Experience with Geant4, Geant3 and Fluka

19 AliROOT 19

20 Simulation and reconstruction 20 Offline Tutorial, , Małgorzata Janik, Łukasz Graczykowski

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29 AliRoot svn structure tag revision trunk trunk svn ls v / v an/ v an/ v an/ v an/ v an/ v an/ v an/ [...] v4-18-rev-01/ v4-18-rev-02/ v4-18-rev-03/ v4-18-rev-04/ v4-18-rev-05/ v4-18-rev-06/ [...] 29

30 Simulation and reconstruction in practice 30

31 31 Offline Tutorial, , Małgorzata Janik, Łukasz Graczykowski

32 32 Offline Tutorial, , Małgorzata Janik, Łukasz Graczykowski

33 33 Offline Tutorial, , Małgorzata Janik, Łukasz Graczykowski

34 Visualisation To run visualisation program for ALICE: alieve root [0].x visscan_local.c (in the directory where simulated data is present, i.e. /test/gun after running sim.c and rec.c macros) 34

35 Thank You! 35