The BESIII Offline Software

Weidong Li

Institute of High Energy Physics, Beijing

Workshop on the cooperation of PRC-US in HEP

16 June 2006

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BESIII Experiment

Muon Chamber (MUC) ：

RPC based

　 　

TOF System ：T = 90 ps barrel

110 ps endcap

Main Drift Chamber (MDC) ：

xy = 130 m

P/P = 0.5 %@1 GeV

dE/dx = 6-7 %

EM Calorimeter (EMC) ： E/E = 2.5 % @ 1 GeV

z, = 0.6 cm @ 1 GeV

Super-conducting Magnet： 1.0 Tesla

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Software Environment Underlying framework

GAUDI (originally developed by LHCb)

Simulation

GEANT4

Other external LIBs:

CERNLIB, CLHEP, ROOT, AIDA, XercesC, GDML …

Database: MySQL

Computer language: C++ (BESII legacy code written in Fortran )

Operation system:

SLC3/ gcc3.2.3

Reused part of code from Belle, BaBar, ATLAS,GLAST

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CMT and CVS

Release area

CVSWork area

sources

Installation area

binaries

packagepackagepackagepackagepackagepackagegenerated

cmt

packagepackagepackagepackagepackagepackage cmt

ExternalExternal

External

External

Internal software

External software HEP software

Public domain software

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Gaudi Infrastructure

The application has an ApplicationMgr and it creates and initializes a set of services.

The EventLoopMgr controls the main physics event loop and schedules execution of algorithms.

We have implemented many BESIII specific Algorithms and Services.

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Framework

GeometryGDML

Data

ExecutionExecution SequenceSequence

Raw Data

RootDstCnvSvc

RawDataCnvSvc

TofGeomSvc

MdcRec

TofRec

MucRec

DST Data

Event Data

Service

EmcRec

Detector DataDetector Data FlowFlow

Event DataEvent Data FlowFlow

NavigationSvc

MagneticFieldSvc

PartPropSvc

MdcGeomSvc

EmcGeomSvc

MucGeomSvc

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Event Data HEPEVT Data

Kinematics information only

RAW Data Delivered by DAQ for reconstruction

Byte stream format

Simulated Event Data Contain digits, hits and other MC truth

information

Root format/byte stream format

REC & DST Data Reconstructed Data is event data written

as output of reconstruction procedure

DST Data is a reduced event representation suitable for analysis

Both in ROOT format

RAW DataRAW DataSimulatedSimulated

Event DataEvent Data

GeneratorGenerator

HEPEVTHEPEVT DataData

G4 SimulationG4 Simulation

ReconstructionReconstruction

REC & DSTREC & DST DataData

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Simulation (1) MDC

TOF Scintillator (EJ200)

Wrapping materials (Al + PVF)

PMT (R5924)

•Stereo layers: Hype

•Stereo Cells ：TwistTube

•Axial layers: Tube Solid •Tube & Endplate constructed use Tube solid

barrel end-cap

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Simulation (2) EMC

G4Trap & G4IrregBox

Added cables,support system

Digitization: readout

electronics is simulated

MUC Detector description detailed to

a single strip

One dimension read-out

Efficiency added according to

position of pad

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Simulation (3)

Generators are legacy code from BES/BESII experiment

Generators communicate with detector simulation through Gaudi Transient Data Store.

Generator(BesGenModule)

Simulation(BesSim)

Reconstruction(MdcPatRec...)

KineInform.

Digi &McTruth

Event

Gen

McTruth

Digi

Recon

Dst

Algorithm Transient Data Store

1

2

3

4

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Reconstruction Algorithms

Sub-detector Reconstruction Algorithms

MDC

MdcPatRec : tracking algorithm based on BaBar software

TrkReco: tracking algorithm based on Belle software

MdcDedxAlg: calculating dE/dx information for MDC tracks.

KalFit: track fitting algorithm using the Kalman Filter method.

TOF TofRec: calculates the flight time of charged particles.

Calorimeter EmcRec: a clustering algorithm for EM Calorimeter.

Muon Chamber MucRec: tracking algorithm for Muon Chamber

Other Algorithms

T0 Calculation: determining the event start time T0.

Tack Extrapolation: considering particles’ deflection in the magnetic field and the ionization energy loss of particles in the material.

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Recon. and simulation algorithms retrieve calibration data from calibration data store

Meta-data stored in database contains: path, valid run interval

Calibration constants are stored in ROOT files

Calibration

Calibration constants

(ROOT)

MySQLdatabase

CalibFuncSvc

Calibration Data

Service

Reconstructionalgorithm

CalibRootCnvSvc

Simulationalgorithm

GUIClient

CalibrationAlgorithm

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Event Display Tool: BesVis

Based on ROOT, OpenGL, X3D and XML

Support both 2D and 3D view

Operations and controls available through menu and toolbar items

Recently MCTruth information was added.

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Physics Analysis Software Analysis Object Builder

Particle Identification

Kinematics Fitting

Vertex Finding

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Major Releases BESIII alpha release

integration with BOOST simulation

Running the reconstruction chain for MDC, TOF, EMC and MUC can be achieved in the BESIII Gaudi framework.

EDM for both Raw Data and reconstructed data developed. Completion of fully functional Event Data I/O.

Status: published in May, 2005

BESIII beta release Simulation and reconstruction chain functions reasonably well and can

successfully process thousands of events.

Common physics analysis tools and utilities available.

Physics study can start.

Status: published in November, 2005

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Event Data Flow

HepEvt McTruthG4Event

HitsDigitsRawDataCnvSvcBES I I I RawData

Generator EventConverters Simulation

Digitization

ReconstructionAlgorithms

CalibrationFucSvc RecHits RecTracks

AnalysisTools DstTracksHistograms

Ntuples

RootDstCnvSvcDstData

Rec2DstAlg

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Performance (1)

TOF reconstruction eff. ~99%

(1GeV electron)

time resolution: ~110 pstime (ns)

entr

ies

MDC momentum and spatial resolution

σxy = 110 μm,

δpt/pt = 0.4% (1GeV μ)

dE/dx= ~6% 1 GeV π

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Performance (2)

MUC Recon. efficiency: ~ 99% @

1GeV

Ratio of fake μ < 10% for π

4E/E=[(p0/E) (p1/ E) p2]%

EMC

σE/E ≈ 2.8%@1GeV

σz = 0.6 cm @1GeV

0

10

20

30

40

50

60

70

80

90

100

0. 5 0. 7 0. 9 1. 1 1. 3 1. 5

mu-90pi -90mu-70pi -70mu-50pi =50mu-40pi -40mu-30pi -30

μ efficiency

π(fake μ )

90 7050

40

30

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BESIII Software Timeline

20032002 2007

2004 2005 2006

Reconstruction Algorithms

Analysis Tools

Calibration and Database Data Challengeand

PerformanceTunning

Event Display

G4 Detector Simulation

BESF framework

BESIII Gaudi framework

Digitization

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Ongoing Activities Detector alignment survey

Mixing of background events

Reconstruction performance optimization

Studies of algorithms’ robustness With background pileup

miss-alignment

Non-uniform magnetic field

Data Challenges

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Summary BESIII has successfully adopted GAUDI application

framework.

Based on Gaudi, the BESIII offline software was developed Simulation

Calibration and reconstruction

Physics analysis

Data challenge and software performance optimization are the major task for 2006.