CBM Software Workshop for Future Challenges in Tracking and Trigger Concepts, GSI, 9 June 2010 Volker Friese

Software for an experiment-to-be Tracking Workshop, GSI, 9 June 2010 V. Friese 2 Simulation Detector description Input (Signal, Background) Simulated signal Performance (acceptance, efficiency) Running experiment Simulation Input (Signal, Background) Required performance (S/B, SNR, eff.) Simulated signal Detector design Planned experiment

V. Friese Software tasks CBMROOT Monte-Carlo Event generator UrQMD, HSD, user defined,... GEN Particles (type, momentum, vertex) MC Transport (MC) GEANT3, GEANT4, FLUKA,... MCPoint, MCTrack RAW Detector response simulation Digi ESD Reconstruction Hits, Tracks, Vertices Analysis Histogram Detector Simulation Step Data level Data structures Tracking Workshop, GSI, 9 June 20103

Software development in CBM A rather small group (~20) of developers with a large range of programming skills –detector groups (geometry, detector response) –reconstruction groups –physics analysis groups Almost exclusively C++ Framework: FAIRROOT (based on ROOT I/O) Build system: Cmake Distribution / version management by subversion Monitoring: CDash Releases about twice per year Tracking Workshop, GSI, 9 June 2010 V. Friese 4

Aspects of software development for CBM Data structures / algorithms should provide maximal flexibility w. r. t. detector design Software should converge to treatment of real data in the running experiment Figures of merit for reconstruction are not only efficiency and accuracy but also (and in particular) speed –must be optimised and tuned to a particular detector solution Tracking Workshop, GSI, 9 June 2010 V. Friese 5

Geometry implementation Tracking Workshop, GSI, 9 June 2010 V. Friese 6 electron + hadron setup muon setup For most subsystems: modular description including supports / inactive materials

Digitisation: STS Tracking Workshop, GSI, 9 June 2010 V. Friese 7 Station segmentation 1-d cluster finding Charge sharing 2-d hits from crossing of cluster centres

Tracking Workshop, GSI, 9 June 2010 V. Friese 8 Digitisation: MVD No Electric Field: Electrons are diffusing θ sensitive volume Charge production and diffusion in the MAPS 2-d charge cluster on pixels

Digitisation: MUCH Tracking Workshop, GSI, 9 June 2010 V. Friese 9 Modular geometry models with overlaps and dead zones Digitisation (charge sharing, cluster finding) analogue to MVD GEM only GEM + Straw Straw digitiser also implemented

Reconstruction tasks Tracking Workshop, GSI, 9 June 2010 V. Friese 10 track finding in STS (+ MVD) track finding in TRD or MUCH ring finding in RICH ECAL shower reconstruction construction of global track (merging local tracks + rings / hits / cluster)

Tracking Workshop, GSI, 9 June 2010 V. Friese 11 Challenges for reconstruction UrQMD, central 25 AGeV D 0, c τ=127 μm K-K- π+π+ Open charm: Typical signal multiplicities: O(10 -6 ) No „easy“ trigger signatures

Tracking Workshop, GSI, 9 June 2010 V. Friese 12 The challenge of rare probes Rare probes (D, J/ψ) · BR = O(10 -6 – 10 -5) SIS-300 I beam = 2 · 10 9 Event rate Raw data flow from FEE TB/s Archival data rate O(1 GB/s) Online event selection data reduction of O( )

Consequences Essential parts of the CBM physics programme can only be realised with extreme interaction rates –fast detectors and read-out electronics –online event selection, requiring reconstruction of large parts of the total event fast reconstruction algorithms! –blurring relation of online and offline reconstruction maybe different levels of accuracy / efficiency Fast reconstructability is design criterion for detectors –detector system and reconstruction algorithm(s) must be regarded as one entity w. r. t. performance Tracking Workshop, GSI, 9 June 2010 V. Friese 13

Free-streaming DAQ Tracking Workshop, GSI, 9 June 2010 V. Friese 14 FEB Det ROC FLES ABB DCB BNet digitizationaggregationbufferingprocessingcorrelation No conventional trigger: no a-priori association of raw data to physical events Construction of events from free-streaming data with time stamps is part of online reconstruction possible on digi / hit level „conventional“ tracking 4d tracking ? yes no