TOF Reconstruction, Calibration & Test-beam Simulation Jiang Linli 2005/6/1 (13th BES Annual Meeting )

Outline  TOF reconstruction software status  TOF primary calibration introduction  A Geant4 simulation of the TOF model test-beam  Summary

 Measure the flight time of charged particles.  Comparing the measured time against the predicted time.  Particle identification. BESIII Design TOF Physics Target : Particle ID

Barrel TOF Endcap TOF

TOF Reconstruction Principle

TOF Reconstruction Software Feature  Experience from Belle TOF reconstruction  C++ code  Developed in the Gaudi framework (Boss)

 Main class TofRec TofSys TofGeom TofCalib TofData TofTrk TofHits TofRec TofSys TofGeom TofCalib TofData TofTrk TofHits  Barrel Tof BTofSys BTofMod BTofCnt BTofScint BTofPhotoTube BTofDat BTofCal BTofSys BTofMod BTofCnt BTofScint BTofPhotoTube BTofDat BTofCal  Endcap Tof ETofSys ETofMod ETofCnt ETofScint ETofPhotoTube ETofDat ETofCal TOF Reconstruction Class Design

TOF Reconstruction Process

Current Status  All the code has been debugged in the Boss4.1, a primary version has been put to the CVS web.  MDC reconstructed track and the extrapolated track are replaced by the MC track truth.

TOF Reconstruction Code Test  Use MC data to do the test  A example : 1000 events electron data (single track )  Reconstruction process as showed above  Primary reconstructed result Now The efficiency of the matching hits and tracks is 100%

χ for Different Charged Particles χ 2 for Different Charged Particles

TOF Primary Calibration TOF Primary Calibration  Time calibration  Attenuation length calibration  Effective velocity calibration

Calibration Software Status  Some program has been developed  Mainly use ROOT  Use the MC data to do the calibration

Time Calibration Result Before Calibration After Calibration σ=125 ps σ=83 ps

Attenuation Length Calibration Effective Velocity Calibration Bulk attenuation length: 4 m

TOF Model Test-beam Setting Chart Target C :  10×80mm Magnet to choose particle’s momentum Cherenkov MWPC 80mm×80mm TOF Model S1S1 S2S2 In one room Pb wall T 02 T 01

A Geant4 Simulation of the TOF Test-beam  Geant4 is a detector simulation toolkit.  It can model the optics of the scintillator.  The processes include refraction and reflection at medium boundaries, bulk absorption and Rayleigh scattering.  It is ideal to simulate the TOF

A Geant4 Simulation of the TOF Test-beam  The simulation program has been finished and used  The detector construct as the test-beam  PMT response is simulated

Simulate Comparison Different thickness scintillator  BC408 4 cm  BC408 5 cm  BC408 6 cm Different reflectivity wrap material  Al r = 82 %  ESR r = 98 %

Different Size Simulation Result Why 5 cm has the best time resolution?

ADC Comparison ADC 4 cm < 5 cm < 6 cm 275.7±1.3 pc 282.7±1.3 pc 288.5±1.3 pc

Pulse Rise Time Comparison Rise time 4cm<5cm<6cm ±0.005 ns ±0.005 ns ±0.005 ns

ADC 6 cm > 5cm > 4cm Rise time 4 cm < 5cm < 6cm So σ 5cm < σ 6cm < σ 4cm σ 5cm < σ 6cm < σ 4cm

Different Reflectivity Simulation  ESR r = 98 %  Al r = 82 %  Npe ESR > Al σ Al < σ ESR ?

ADC Comparison ADC Comparison ADC Al < ESR ±1.3 pc ±1.7 pc

3.736±0.005 ns Pulse Rise Time Comparison ADC ESR>Al but Rise time Al<ESR but Rise time Al<ESR So σ Al < σ ESR So σ Al < σ ESR 3.956±0.006 ns

Summary  TOF reconstruction software has been developed, and there is a primary version.  Primary TOF calibration has been done.  A Geant4 simulation of the TOF test-beam has been done, Some experiment result can be explained by simulation.

Next to do  More TOF reconstruction work  A complete TOF calibration software development  Calibration methods study  More detailed simulation work

Thank you !