1 Software Applications in High Energy Physics Experiments Lecture number 4, prepared by Paweł Staszel

2 Outline 1. Data objects (classes) 2. Data containers 3. Modules – classes that operate on data 4. Containers of modules 5. Building program (reconstruction task) from modules → singleton class MainModule 6. Main program: bratmain

3 Modules in BRAT brat/modules – classes that manipulate on data: Important feature of modules is algorithm that converts data to a higher level: dig → rdo → local tracks → global tracks → dst → tree with reconstructed events. Data classes: define structure of data Modules: contain algorithms that process these data abc – BrModule – base class of every module BrModuleContainer – class, which is container of modules. It controls the order in which the methods of component modules are executed. Setup of this BrModuleContainer defines the particular process which is usually part of the data reconstruction/calibration/analysis process i

4 BrModule- handles important scheme (methods) for every module

5 Diagram showing a processing scheme for a single module constructor + setup → booking of diagnostic histograms → access to data base to read process parameters (calibration data, geometry of detector setup, run info...) Setup related to a given run: → histogram booking → calibration parameters from db,.... Data processing on event by event basis – new data structures are created and written to output data container (outNode) Post run processing operations Post process operations (finishing the job)

6 BrModuleContainer- ordered collection (chain ) of modules

7 BrModuleContainer- some important methods

8 BrModuleContainer- pipeline of modules (ordered execution) Basic data: raw hits, Calib. parameters Reconstructed physical data tracks+pid = particles, Global information about collision: → impact parameter (centrality) → collision vertex → overall multiplicity

9 BrModuleContainer – standard methods executed in the chain (Init())

10 BrModuleContainer – standard methods executed in the chain (Event())

11 BrModuleContainer – setup/info methods executed in the chain

12 BrMainModule – singleton, basic module of particular analysis (process)

13 BrMainModule – fgInstance and constructor

14 BrMainModule – Main() function