EicRoot software framework Alexander Kiselev EIC Software Meeting Jefferson Lab September,24 2015
Contents of the talk FairRoot software project EicRoot framework structure Typical EicRoot applications Summary 2/26
FairRoot & EicRoot
FairRoot overview Active project, officially supported by GSI Large experiment and user base Regular releases, active forums, long-term developer support Several software building blocks readily available Designed with flexibility in mind Simulation and reconstruction in the same environment ROOT-based I/O Virtual geometry concept (several formats supported) Virtual Monte-Carlo concept (easy switching between GEANT 3 & 4 transport engines in particular) 4/26
FairRoot experiments Slide from Florian Uhlig presentation at ROOT 2015 Workshop last week 5/26
EicRoot framework building blocks Interface to GEANT, ROOT, PandaRoot FairBase FopiRoot Ideal track finder, Interface to GenFit eic-smear EicRoot TPC R&D stuff, CbmRoot MC generated evts import Fast smearing codes solenoid modeling IR design configuration RICH stuff 6/26
End user view No executable (steering through ROOT macro scripts) simulation digitization reconstruction PID; assembly -> MC points -> Hits -> Tracks, clusters -> Events ROOT files for analysis available after each step C++ class structure is well defined at each I/O stage 7/26
Geometry description Input formats: ROOT TGeo GEANT GDML Old HADES.geo files CAD design drawings (.stp,.stl,.slp) Output format: ROOT TGeo 8/26
Typical applications Physics analysis Test beam data analysis R&D studies Tracking Calorimetry RICH simulations (FopiRoot codes adapted) TPC modeling (CbmRoot codes adapted) 9/26
Physics analysis
What is available? Rather detailed EIC model detector description Interaction region configuration (apertures, fields) Possibility to import generated physics events Tracking and calorimeter reconstruction Event assembling, simple PID algorithms, etc 11/26
erhic model detector layout -4<η<4: Tracking & e/m Calorimetry (hermetic coverage) hadronic calorimeters e/m calorimeters RICH detectors SBS CBM EIC R&D (UCLA, BNL) EIC R&D (UCLA, BNL) ALICE silicon trackers TPC GEM trackers 3T solenoid coils 12/26
Interaction Region implementation Roman Pots location Main detector Low Q 2 tagger location -> field maps and magnet aperture sizes imported automatically -> Roman Pots, Low Q 2 tagger & Lumi Monitor (partly) implemented 13/26
EIC smearing generator interface MC generator ASCII output Tree code: Build ROOT tree containing events Smearer: Perform fast detector smearing PEPSI Rapgap PYTHIA Milou LEPTO DPMJet gmc_trans Djangoh Large number of EIC Monte Carlo generators with standard ASCII format Both event import and smearing functionality is supported in EicRoot 14/26
DIS kinematic variable reconstruction {PYTHIA 20x250 GeV, NO bremsstrahlung} -> {GEANT 3} -> {Kalman filter track fit} same procedure; simulation WITH bremsstrahlung 15/26
Purity in (x,q 2 ) kinematic bins Describes migration between kinematic bins Important to keep it close to 1.0 for successful unfolding bremsstrahlung OFF bremsstrahlung ON Bremsstrahlung matters even for detector with ~5% X/X 0 Straightforward tracking can hardly help at Y<0.1 NB: one can use EmCal info or hadronic method for kinematics calculation to extend small Y range 16/26
Tracking R&D -> see next talk
Calorimetry R&D
Calorimeter code implementation Written from scratch (use ideas rather than codes) ATLAS fast simulation ( frozen showers) CMS topological cluster search Unified interface (geometry definition, digitization, clustering) for all EIC calorimeter types Rather detailed digitization: configurable light yield exponential decay time; light collection in a time window attenuation length; possible light reflection on one cell end SiPM dark counting rate; APD gain, ENF, ENC configurable thresholds 19/26
STAR EmCal upgrade simulations 3 degree track-to-tower-axis incident angle Exact geometry description Realistic digitization stands for: 40MHz SiPM noise in 50ns gate; 4m attenuation length; 5 pixel single tower threshold; 70% light reflection on upstream fiber end; -> good agreement with original MC studies and measured data 20/26
STAR HCal upgrade simulations 12 GeV pions: Hcal vs EmCal - GEANT 4, FTFP_BERT physics list - Birk s correction accounted by hand slope ~1.20 -energy resolution comparable to ZEUS 1987 paper HCal EmCal 21/26
Calorimetry designer tools As long as the following is true: your dream calorimeter is a logical 2D matrix composed of long cells as elementary units, all the game is based on (known) light output per energy deposit, energy resolution after ideal digitization suffices as a result one can with a moderate effort (99% of which is writing a ROOT C macro with geometry and mapping description) build custom EicRoot-friendly calorimeter which can be used for both standalone resolution studies and/or as an optional EIC device (and internal cell structure does not matter) -> see examples/calorimetry directory for details 22/26
Other applications
Older studies ephenix forward tracker momentum resolution STAR forward tracker upgrade simulations sphenix sampling EmCal energy resolution FLYSUB test beam data analysis (GEM prototypes) 24/26
Recent stuff: neutron flux estimation STAR TGeo geometry imported in EicRoot BeAST detector placed in STAR hall Strategy: Import STAR experiment geometry (including experimental hall) Run ep- and pp-pythia simulations for STAR and BeAST setups Use direct STAR neutron flux measurements from 2013 as a reference NB: prefer GEANT 3 (GCALOR available) n/cm 2 / 1MHz PYTHIA 20x250 GeV ep-events At most ~10 10 n/cm 2 per year of running at L=10 33 cm -2 s -1 25/26
Take away message EicRoot can be used as is for standalone R&D studies Several ready-to-go examples exist Codes available for download from BNL SVN server 26/26